Thanks for the experience sharing and the blog, it is very interesting to read and your humility about the feedback is definitively appreciated.
I currently also did my own DIY EVSE charger mainly for fun [1].
If you are interested about the main differences between your approach and mine:
(1) I use an industrial contactor DIN form factor for the power switch instead of passing the power through the relay directly. Mainly for safety reasons (I do not trust much small relays) and also because I wanted to support three-phase power for an European T2 installation.
(2) Instead of printing my own PCB with an Arduino for the PWN, I just bought one command module from China/UK provider. Mainly for pure lazyness reason :) The module itself is shield behind the RCD class B.
(3) I have added a shelly 3EM front of the system. To use it as a watt-meter with MQTT report and also as a remote control system.
My little advice for people interested to do their own: DIY is always an excellent way to learn and if you want to do your own, do it... BUT please make your installation reviewed by someone with an electrical engineering or technician background if possible. These systems can easily pump 7 to 22KW during extended period of time: Any cable which is not screwed properly or under-sized can bring you a fire.
"It costs about £900 in the UK to have an EV charger installed by an electrician"
£900 is $1140. In southern California, it cost me $750 for top notch work and hardware, including: $400 to have an electrician install a 240V 50A outdoor outlet (NEMA 14-50), plus $350 for a good quality level 2 40A EVSE (this one: https://www.amazon.com/dp/B082LMVSLY) that I installed myself as it simply plugs in the outlet and it's just a 5-minute job to secure it to the wall with two screws.
It's possible to bring the cost down to around $600 when picking a cheaper EVSE (like https://www.amazon.com/dp/B08LMX4TJR?th=1), so about half the UK cost as reported in the blog post. I would love to see a breakdown of that £900... that seems really high.
> I would love to see a breakdown of that £900... that seems really high.
The £900 will include: supply of a 7kW EVSE; adding a new circuit to your consumer unit/fuse box; running a few tens of meters of fairly expensive cable (6mm SWA suitable for outdoor and underground use) in a careful, tidy way; adding an extra ground point, if needed; an electrical safety test with a special tester; and issuing a certificate (which is mandatory for this type of installation). It'll take the electrician about a day.
People in the UK pay a fairly hefty premium as we don't have as many qualified installers as we probably ought to.
Of course, standard British sockets already supply 3kW - so the cheaper option is just to get an outdoor socket installed on an existing ring main. This is substantially quicker to install in most cases.
> the cheaper option is just to get an outdoor socket installed on an existing ring main
From my searching, this doesn't meet the current regulations of the socket is intended for EV use. The costs to make it compliant bring it up to the better options anyway.
It goes without saying that you've got to have a 'granny cable' with appropriate protection - but AFAIK every EV comes with one of those.
And of course, you'd fit a socket like [1] which is waterproof even when in use, and has a built-in RCD if your consumer unit doesn't have one. It's common sense when using electricity outside. And your installer will want to make sure the circuit has enough capacity to avoid nuisance trips - put your EV on the same circuit as your kettle, washing machine, dish washer and tumble dryer and you'll have a frustrating time :)
But my point is, not every Brit with an EV spends £900 on EVSE - especially if they're only commuting two days a week, or they've got a plug-in hybrid.
Sample of 1 but yeah we have a plug in hybrid and and waterproof socket in the storm porch, the car charges in a few hours. No desire to spend nearly 1k to charge a bit quicker
£900 seems cheap to me. I'm in Belgium and I installed a charging point at my house earlier this year. The cheapest quote I got was 1300 euros.
I ended up installing one myself, but spent almost as much anyway. 800 euro for an Alfen Eve charging point with support for OCCP protocol (for reimbursement of electricity cost by employer), about 200 euros in other materials (admittedly with some scope creep), 150 euros for the mandatory technical inspection...
Another recent example: I'm in Switzerland. I paid 550 CHF (630$) this summer for a "go-e Gemini" charger. I screwed it to the wall and ran a roughly 15m 3-phase 16A cable to the main fuse box (maybe around 50 CHF for cable and installation tubes), where an electrician connected it properly for 108 CHF (124$) and added an appropriate RCD for 116 CHF (133$). All in all, it cost me around 800-900 CHF (900-1000$).
Without doing some of the installation work myself, the electrician would have cost me several hundred CHF more.
From some searching, I think paying an electrician to install a 32A CEE socket (often called "Commando" in Britain after a particular manufacturer) and then installing the EVSE yourself would be similar. Although there do seem to be some safety requirements for the socket if it's to be used for charging EVs, which increase the cost.
I talked to the electrician about using a CEE16 connector to charge the car. He said that this should only be done if you don't load it near its max (16A) for long periods of time. He's seen multiple CEE16 connectors that deformed condsiderably after a year of use with regular charging sessions at 16A. If you load it to 10-12A, it should be fine.
I have servers and UPSs and so on connected with these sockets, drawing a high current 24/7. Just like every datacentre in Europe, UK included. They are only very rarely unplugged though.
Is it a case of using a high quality socket which costs 2-3 times as much?
Not the person you're asking, but it might also be where it is installed. The connector I looked up online is rated to +40C, and being located in direct sunlight on a hot day could derate the connector compared to a temperature controlled environment. Add in some dirt or corrosion in the connector and it will generate more heat. Like you said about buying a high quality connector, something with more margin in terms of current will help prevent problems from developing.
The electrician may have been referring to the 16 amp connector specifically being too close to the charging current.
Thank you for the dozen of you who responded. It's fascinating for me to see the large range of price points due to different regulations in different countries and also affected by different needs (eg. need to track kWh for subsdies).
I'm in the UK and I've got a charger being installed next week. The basic Ohme model is costing me £900 installed. Prices were the same pretty much everywhere I looked.
No one looks at it this way, because extremely few people buy cars with cash. Majority of buyers buy a car on finance - and compared to the monthly £500 a car might cost you, £900 is not insignificant, that's nearly two car payments, and also I have no idea how wealthy you'd have to be to call £900 "pocket change".
We have an EV and a PHEV, I had a charger installed back when government grants were much more generous, we paid £250 to have one installed, but nowadays I think I'd just make do with a 3 pin charger, or get a commando socket installed + OHME 32amp commando socket charger, much cheaper than this.
I used a granny charger for the first 3 weeks after getting my EV. I don't use the car that much but even so, the painfully slow charging made it a hassle. And also remember, if you want access to cheap electricity, you need to use a "real" EVSE. This DIY one can't provide access to that either.
>>And also remember, if you want access to cheap electricity, you need to use a "real" EVSE.
Why? I was on Octopus Go for a long time, I'd just set the in-car timer to charge between 00:30 and 04:30, worked fine even with a 3-pin charger. It won't work with Intelligent Octopus, but it's by no means the only way to get cheap electricity.
Not that it matters anyway, I kept a detailed log of our usage for months and concluded that GO wasn't actually saving us any money, the cheaper electricity at night didn't offset the energy used during the day, not at the idiotic prices they charged for peak usage anyway. We just switched to Octopus Tracker, I can charge my car at any point during the day and it's actually cheaper than being on GO.
You are right, sorry. I forgot there's the non-intelligent version. Although you can't put in much in just 4 (I think?) hours with a granny on Go.
Intelligent Go is saving me a lot. But the peak rate where I am (I believe it varies by region) is only a few pence more than the cap. And I'm trying to use washing machine etc only off-peak where possible. My bill is now less compared to before I had the EV.
Yeah but the cap is stupid - on tracker I've been consistently paying 20p/kWh or less.
And yes I was always scheduling the washing machine and dishwasher for the cheap hours at night, but we both work from home, both run a lot of equipment, the daytime cost just was destroying any savings made during the night. But again, that's just us and our situation.
Presumably if someone drives enough that they need more than four (or whatever) hours of charging overnight, they will need a higher power charger to take advantage of the cheapest hours.
Of course. I'm just saying that if our charger broke tomorrow I don't think I'd pay £900 for a new one, it's just too much money imho, but our personal situation works even with the slow 3 pin charging.
I would have liked to see a cost breakdown. If it's significantly cheaper than OpenEVSE (somewhwere between $500-$600 depending on which kit you get), then maybe some people would be willing to take the risk (it seems like there are some safety concerns with his design that I don't feel qualified to adjudicate).
But without some kind of a cost difference, I'd probably stick with something like OpenEVS, which seems to have some level of official certification [0].
I personally regret my decision to not go with them when I got my EVSE this year. I went with an EnelX Juicenet because A) it was on the list of devices my power company would mostly pay for and B) at the time it had API availability to integrate with HomeAssistant. They have since killed that second part, which I would have loved to still have. In the long term, the ~$500 I saved by having my power company reimburse was probably not worth the lack of control I now have.
-edit- He does have a total cost, I just missed it: he claims that it was ~£200. I leave it up to the reader if that's enough savings to give up the certification.
OpenEVSE can be a codebase or a kit. If you want to source all your own parts, or maybe reuse significant parts of a non-open EVSE and just drop the processor into it or whatever, then it can be very cheap indeed. If you buy their branded kit, then full price applies.
When OpenEVSE was new, I built one on perfboard, actually a very compact modular stack of perfboards, one layer per subsystem. Handed it off to my software-savvy friend, and he couldn't get it to pass self-test, despite both of us agreeing that every piece of the circuit appeared correct as per the published schematic.
Eventually he gave up and ordered one of OpenEVSE's commercially-produced boards, and it failed self-test at the exact same place. Apparently there was some unclear documentation and it was supposed to fail there until something else was hooked up, I don't remember the details, but there was nothing wrong with my stack of perf in the first place. Argh.
All of which is to say, it's not hard at all to build one of these things. if you want to lobotomize your closed-crap EVSE and lash an open board to it, do so! I'm pretty sure the JuiceBox is OpenEVSE-based in the first place so it might be as simple as reflashing some firmware.
What I don’t understand is what the motivation for manufacturers to not just install the open software is… are they trying to harvest charge time data or something? It seems like it would be easier to change any logos in software but leave the rest as is. Non tech buyers wouldn’t know or care… and nerds would buy it in droves. This goes for a lot of the low end network gear too. Are they really adding much value in software?
They must believe that there is, regardless of whether or not their _actually_ is. Manufacturers killing local control that is only used by extremely small numbers of their users is a pattern [0]. The only potential good reason I can think of is if the existence of these abilities allows users to get themselves into trouble when they don't fully know what they are doing, which could create a great deal of (expensive) support and so they decide to just remove the headache
oh wow, thank you. I'm going to look into this. I have been extremely unhappy with JuiceBox's app/etc the entire time I've had it. If I can reflash it (and/or relatively easily replace the brains), that would dramatically improve my charging situation).
After reading this article, I had been considering getting one of their most basic kits that doesn't include the cables from the wall to the box or the box to the car (since I have both of those with my current EVSE), but if I can get the same functionality reusing even more of my current one, that would be ideal.
The name itself, Electric Vehicle Supply Equipment, indicates the focus of the hardware beyond simply being a fancy plug and a contactor. Higher end EVSE will do things like load balancing a shared supply of power (ie chaining multiple Tesla EVSEs to the same 50A line), setting supply power limits depending on how much power is in use (ie the Porsche Connect Plus modulating lower current when a clothing dryer starts), and managing Car to Grid functionality (Hyundai).
EVSEs also manage DC charging in commercial settings, which bypasses part of the charging hardware in some cars.
My Porsche Taycan is available with multiple chargers from the factory. I have the faster AC charger unit and there is a third unit that is only sold in Europe for Type 2 chargers. The actual charger handles converting AC to DC, which is car specific and why it’s not in the EVSE.
> The name itself, Electric Vehicle Supply Equipment, indicates the focus of the hardware beyond simply being a fancy plug and a contactor.
Thank you, I wasn't previously aware of this distinction.
So for simple units that are just "a fancy plug and contactor" (no balancing, limiting, V2G, V1G, etc), what do we call them? I know not to say "EVSE" now, but what should I use? Thanks again.
The terminology is kind of confusing, but usually the thing called a "charger" is the part that converts AC to DC at whatever voltage the pack requires.
For level 1 and 2 charging, the charger is in the car. J1772 ports are basically just fancy 110v or 220v AC plugs with some extra signalling.
DC charging tends to happen at much higher power levels, and that equipment is expensive so the AC-DC converter is kept outside of the car. The car itself just has a couple contactors (i.e. high power relays) to connect the charge port directly to the battery, and a microcontroller to tell the charger how much current it can handle at what voltage.
And yet the technical people need accurate names to call things so they can communicate without ambiguity.
I think "charging station" is the least confusing term for the fixed infrastructure part. If regular people call those "chargers" in non-technical conversation, then I'm not going to lose sleep over it.
The thing that you use to provide your phone with electricity - do you call it an AC-DC converter, or do you call it a charger like nearly everyone on earth, even though the charger part is actually inside your phone?
It's funny that people don't want to call it a charger specifically because it doesn't do the AC-DC conversion, and your example of a thing people call a charger is an AC-DC converter.
And depending on the sophistication of the phone, that converter outside the phone might be doing most of the work.
>>It's funny that people don't want to call it a charger specifically because it doesn't do the AC-DC conversion
Well yeah, they are being silly - I don't know why that would be the distinction, even if it did AC-DC conversion it would have no idea what the battery is doing which is the entire point.
>>that converter outside the phone might be doing most of the work.
Maybe, but usually the circuit that controls and monitors the battery is inside the phone, not in the "charger" outside. Even battery chargers for power tools and such work this way - the circuit that controls the battery charging is actually inside the battery pack not in the base, but everyone would call the base a "charger".
The EVSE is a glorified RCD/GFCI cord with a contactor that turns on power, so the cord is dead until that happens. It also generates a signal that tells the car how much power it's allowed to draw; the EVSE is configured at install time to know what size breaker feeds it upstream, so it tells the car not to trip that breaker, but the EVSE has no means of actually enforcing such a limit. There's some basic negotiation between the EVSE and the car, to decide when the plug is inserted and it's OK to turn on the contactor.
The AC power passes straight through the EVSE, unaltered in voltage, current, or waveform. The EVSE may monitor the current to perform logging, and the EVSE is required to monitor the AC imbalance like any other RCD/GFCI does so it can open the contactor if there's a ground fault, but that's it. It's just a smart extension cord, basically.
The charger is in the car, and is the component that actually converts the AC from the grid to DC for the batteries. The charger is what has all the silicon (or these days, probably gallium nitride?), and the inductors and capacitors and stuff to actually transform the power from one form to another. It changes the voltage to match whatever the battery needs at the moment. It controls its own DC output to match the battery's needs, and it limits its own AC input according to the signal from the EVSE so it doesn't trip the upstream breaker.
The charger is also responsible for immediately turning itself off, reducing its input draw to zero, within a few milliseconds of someone pressing the latch of the EVSE connector handle. This indicates they're about to pull it out, and the contacts aren't designed to handle arcing, so the charger is required to drop its current _very_ quickly, allowing the contacts to be separated without creating an arc. That signal (called PP) is produced in the handle itself, there's just a tiny switch underneath the latch. The handle is technically part of the cord which is technically part of the EVSE, but the EVSE has no responsibilities related to the signal, that's all on the charger.
If the SAE hadn't mandated that the EVSE perform RCD functions, it could be replaced by a literal extension cord. Many small DIY EVs do precisely that; the charge cord is the exact same one you'd use to run any appliance. It works just fine. But even small DIY EVs have a real charger too, which converts the AC from the cord to DC for the batteries. The charger plugs into the cord, but the charger is not the cord.
Everyone calls them chargers. If you said "do you like the EVSE you have?" or "do you know where the nearest EVSE is?" most people would stare at you with a blank expression.
Safety certifications add to cost. We recently took an EVSE through certification and although we passed on the first try it was still expensive and to pass on the first try we did extensive testing and documentation before submission.
Well there is also software... I really liked go-eCharger HOME+ 11kW, because it has 3-phase "European connector" and I can go almost anywhere in europe take it with me and charge there... I usually take it with me when I go to my parents so I don't have to stop on way at fast charger... Anyway.. I paid 650EUR, well above price of parts cost...
But mobile app and firmware keep getting updated and it keeps getting features like "charge from solar" better scheduler, also supports multiple chargers to limit total amps...
At first, relatively low volume and lack of competition (this has improved), and testing for compliance with all the various standards. It's often not enough to just have a product examined/tested, some standards require periodic "surveillance" of manufacturing.
I see $200 evse’s on amazon nowadays. Only 32 amps tho. As to why they are so expensive one has to keep in mind these are inherently dangerous so they do not buy the cheapest parts, they have to go through a longish federal approval process and the companies probably have higher insurance costs.
> As to why they are so expensive one has to keep in mind these are inherently dangerous so they do not buy the cheapest parts, they have to go through a longish federal approval process and the companies probably have higher insurance costs.
We hope. I don't trust anything being sold on Amazon or any other such website known for scams, knockoffs, and otherwise shite products being passed for legit. I'm less concerned about the price of the components vs the quality of the components. You can have cheap quality but a high price just to fool people that expensive is good.
I'm not an EE, but I work with them. As it stands right now, governments don't directly approve consumer products, except perhaps in some rare cases. When my employer gets a new product certified, we take it to a private firm.
As with the misnomers about the "charger" terminology, I could appreciate a layperson getting this confused.
Most people aren't going to DIY something like this. Also, most people think that the price of a product should only be based on the price of its components, and possibly willing to accept a mark up on labor. However, the companies making a thing, whatever that thing might be, also has to make money to be able to pay the people that work for the company, the utility bills, and the rent. There's also the fact that the companies making a thing don't get the retail price you pay. They sell it at the wholesale rate to the vendors, so there's even less margin than the retail price suggest for the makers.
In engineering university, I learned the “retail needs to be 5x the BoM* cost” rule of thumb. For a very high value or very high units product, maybe you could shave that to 4x or slightly less, but there are a lot of hands between the designed part and the retail consumer and none of them want to work for free.
* BoM - Bill of Materials (“what stuff goes into this thing?”)
4x was also the minimum retail price I've been taught as well. The wholesale rate has also been anywhere from 50% - 75% of the retail price depending on the negotiations with the retailer. This is ignoring soulless companies like Walmarts/Amazons/etc where you'll never make those numbers. Something people don't always consider that when they buy something from the retailer directly, they typically make more money from that sale than if you bought the same thing from Walmart. Buying something from somewhere like Etsy vs their direct site also takes a healthy chunk.
That’s what I find so infuriating about many first-party sites.
I’ll often find something on Amazon and if it seems like it’s from a small business, I’ll check to see if I can buy it direct. (Arguably, this behavior is unethical on my part against Amazon, but whatever.)
I very rarely (like <10% of the time) find the first-party site to have an offer that even matches Amazon’s.
Look, I tried. I came to you and gave you a shot, but if you want to charge the same item price and also tack on $15 of shipping, I’ve received your message (“please buy it from Amazon; we don’t want to sell it to you direct…”) loud and clear.
I’m usually willing to wait a few extra days, pay the same price, and have worse returns possibility in order for you to double or triple your variable transaction profit, but you’ve got to be competitive.
Sounds like the manufacturer just wants to ship palettes of the product to amazon and not deal directly with individual customers and are happy to have amazon make their markup for the service they provide.
Yeah, sites willing to accept the full retail price and not discount the shipping to match a larger vendor's site, then of course they're firing their footgun with both barrels. There's a reason places will offer free shipping with minimum purchase prices that ensures there's enough profit made to cover the cost of the shipping.
The hassle of inventory/shipping logistics is something people with no experience easily do not consider.
>I’ll often find something on Amazon and if it seems like it’s from a small business, I’ll check to see if I can buy it direct. (Arguably, this behavior is unethical on my part against Amazon, but whatever.)
According to whom? The people who think going to the bathroom during a TV commercial break is "stealing"?
I don’t think comparison shopping is unethical; it’s what makes a market work.
I do think “thank you for letting me know this product exists and meets my need, but if all else is equal to me, I’ll buy it somewhere else where you don’t benefit from the effort to help me address my need” is not the standard that I hold myself to generally.
Further, I think many would object if I found a product through a small business directly and bought it for the identical terms via Amazon rather than direct.
You have to find out about the product somewhere, whether it's from a small business, or from Amazon. After that point, then you comparison-shop. So how's the market supposed to work if you're only ethically able to buy it from the first place you saw it? Or do you think you're only allowed to comparison-shop for things you buy repeatedly (like milk and eggs) or things you learn about through advertising?
My personal belief system is "it's fine to buy it from the place that's cheapest/most convenient/otherwise best, but in the case of ties, you should buy it from the place that was most helpful".
A lot of people would "shop" at brick-n-mortar stores with a mobile comparing prices online. They would look at the physical item right then and there, but purchase from online. At least, that was the early days of online when people were still actually getting off their couches.
I think price comparison is totally valid, even across channels. But if the online price is the same as brick/mortar, it seems only fair to buy it from the brick/mortar store if they provided you some knowledge/service that the online places did not.
in the early days of online shopping, online didn't charge taxes && gave free shipping. so if you didn't need it right then, it could be at least 8.25% cheaper where I live
Yes, just like your phone charger isn't a charger, yet I see absolutely no point in arguing about it, literally everyone understands what you mean when you call it a charger.
That's not accurate. The EVSE communicates a max current to the vehicle, but does nothing to actively control the current. It should monitor the current and kill the circuit if the vehicle attempts to draw too much, but that only happens after the vehicle has misbehaved.
Correct. The control pilot signal from EVSE to EV is a PWM signal that indicates to the EV how much current is available.
It could drop at any time due to, for example, many chargers being connected to 1 circuit and the chargers coordinating with each-other to load-balance their connected vehicles (everyone gets their fair share), or it could be tied to solar PV generation so that charging doesn't import from the grid; the available current will change with how much excess PV is available, etc.
A well-engineered EVSE will notice when the EV is drawing more than the EVSE wants it to. It should then open the mains contactor at this point; cutting the EV's electricity supply. It will also hold the control pilot low to signal a fault to the EV.
This completely goes against my understanding of electricity. The correct amount of amps are pulled by the plugged in device, and it doesn't matter how much are available at the supply side (as long as it meets the minimum.)
Any good DC lab power supply can operate as a constant voltage source or constant current source. By default, the power supply will maintain a constant voltage at the terminals, but if the connected device starts too pull a current that's higher than the specified limit, the power supply will lower the voltage to keep the current in check.
Not saying this is the case here, of course, but they could do something similar that way if they wanted to...
These are not DC power supplies, thats whats inside the car, a boost DC power supply converting 240v AC to 400v or 800v DC, thats what regulates current and voltage to the batteries.
If the AC "charger" attempted to regulate current by varying voltage the actual onboard charger would just attempt to pull more current to make up for the voltage drop and probably trip the whole thing.
There would be no point in regulating the AC current, it would make the charger very complicated and expensive replicating much of whats in the DC converter/charger in the car.
A full DC charger like at a charging station does do this because it is the actual charger bypassing the cars small internal DC charger with DC leads going directly to battery at full pack voltage.
Got a reference for that? As far as I know (as the linked article says), the EVSE doesn't do anything to control the current other than telling the car how much it can draw.
I've run something similar for 5 years, using https://www.smartevse.nl/ as the brains. The main advantages over commercial EVSE's in my case were that I could loadbalance charging the car with the electricity demands of the house, and that I could have the EVSE itself inside, so that there's no 240V current on any circuit from the breaker box indoors towards the car when there's no car present.
I do intend to add a second sometime, so that I can put the EVSE in my home automation UI as well; the version 2 of smartevse that I use does not have a network connection, but it can be connected to be controlled by a version 3 that does.
I'm disappointed at the anti-DIY sentiments here, it's this safety obsessed mentality that got us to where kids can't walk outside by themselves any longer.
The box in that guy's build is outside and could probably burn to a crisp without hurting anything else. I suspect it would not hurt anything even inside a garage, other than making a lot of smoke and setting off smoke detectors.
All the no-name $6 extension cords from Amazon that we have in our homes are far more likely to burn your place down than this project.
It's surprising that we have such cavalier attitudes when it comes to our own field, but so much fear and magical thinking about the power of government oversight when it comes to everything else...
> It's surprising that we have such cavalier attitudes when it comes to our own field, but so much fear and magical thinking about the power of government oversight when it comes to everything else...
You must be new to HN. Let me introduce you to the two types of comments:
1) The problem I am responding to does not involve software. The people in that industry must not be competent. Therefore, the solution is more government regulation.
2) The problem I am responding to involves software. Everyone in my industry is highly competent and moral! Therefore, let the free markets operate and the problem will automatically disappear.
>I'm disappointed at the anti-DIY sentiments here, it's this safety obsessed mentality that got us to where kids can't walk outside by themselves any longer.
Just no? That analogy is EXTREMELY strained. From his own link: A word about safety. I’m not an electrician. I’m not allowed to make alterations to my consumer unit.
I let my kids play outside all the time solo and with friends without supervision. On the flip side, I don't do things like design my own L2 charger because it violates several codes, would nullify my homeowners insurance, and could quite literally land me in prison should I mess it up and cause a licensed electrician to die because I did something dumb or cause my car to start on fire killing my family.
Do I do my own wiring? Absolutely.
Would I mess around with attaching something at 240v that I made from scratch that could burn my house down and kill my family if I do it wrong? Nope, I'm good.
> I’m not an electrician. I’m not allowed to make alterations to my consumer unit.
It's funny how we reach a society where you need government as a babysitter and tell what you can do and whatnot.
> Would I mess around with attaching something at 240v that I made from scratch that could burn my house down and kill my family
It's also funny how those people readily plug in any consumer device they buy on amazon, which is assembled in china/india without any thought about safety.
Every code regulation is written because some forces lobbied it. It’s nice to think those forces care about you and me, but it’s also incredibly naive.
I'm not sure that's true in the UK. The law changed a few years ago limiting the kind of changes you can make to your home wiring, and you have to have a certificate for new circuit installations or significant modifications. I would not want to be the test case for finding out if this did invalidate your home insurance.
What is up with this common refrain? One of the main functions of insurance is to indemnify you against your own negligence. Let's say you turn a small stovetop fire into a house fire by trying to put it out with water - the insurance company doesn't just get to stiff you because you were responsible for causing the problem. Are there actually prevalent and enforceable weasel clauses about DIY work in some areas, or is this a scare story popularized by oversocialized redditors fantasizing about what might happen, or what?
Homeowner's insurance assumes you're doing your due diligence to not do things that unnecessarily destroy your home. Negligence is specifically not covered when it's something that you should have reasonably been able to prevent. There's a difference between a panic-induced response that makes an accidental fire worse and you making the explicit decision to install something unsafe.
I see the distinction you're making with my specific example, but I'm aware of no such distinction for the policies I've had. Are you referencing any concrete laws or contractual terms?
Also then, a different example: You plug in a non-NRTL-tested appliance from Amazon, and it burns down your house. Clearly outside the bounds of what is prudent, but also something many people commonly do. You're telling me that insurance is set up to stiff all of them, and yet we're not seeing endless news articles about that happening?
Ianal but the law often seems to work on the basis of terms like reasonable or expected. Buying junk electronics from Amazon is so common and risks so little publicised that it doesn’t seem reasonable to exclude them. Building a diy power supply is very uncommon and almost certainly requires knowledge to do so that would also tell you it’s a dumb idea.
As an aside- do cheap electronics actually burn a lot of houses down, or is that scare mongering? I half remember reading that it was large white goods like dishwashers and washing machines that actually started most fires, and they are not typically bought on Amazon or only on price.
If you can find some laws or contractual terms where some homeowners insurance is disclaiming homeowners doing things that are not "reasonable", I'm all ears. I'd love to find out where this meme started, or a list of jurisdictions where this can actually happen. I just think this tendency to assert that DIY causes all these scary things, especially on the pan-jurisdiction Web, is terribly harmful FUD. It appears to be from the same vein as that "voiding your warranty" nonsense (which has thankfully started to go away).
That refrain is common enough that I even ended up reading my homeowners policy, and I didn't find anything in there that excluded unpermitted work, even if I did the work myself, even if I failed to follow code.
And if you think about it, such an exclusion would be crazy. The average homeowner is in no position to judge whether the work someone they hired does exceeds the scope of their license, or whether all the details of the work that need a permit get one, or whether work any work that doesn't get inspected is in fact done to code. Furthermore, the average homeowner isn't the original owner of their house, and is in no position to know what tomfoolery the prior owner might have done.
For those of you out there that are certain that DIY electrical work voids your homeowners insurance, can you prove any evidence to support your claim? A local news story about a guy whose homeowners insurance denied him because he DIY'ed something in good faith? A FAQ page from an insurer that says that DIY'ing something voids the insurance? Anything other than a vague reference to there being a lot of words in your policy and it gets interpreted through the lens of an enormous body of caselaw and the insurance company can afford more lawyers than you?
Insurance regularly pays out when people do stupid stuff and cause a loss to their own insured property, as long as they weren't trying to do damage. Doing stupid stuff that happens to involve electricity doesn't seem any different to me. And frankly, building your own L2 charger after much research and thinking about the safety aspects seems like a far cry from a "here hold my beer" moment.
I don't live in the US (in New Zealand), but this made me check my policies. I'm no longer a home owner but I checked my policy from a couple of years ago, and I checked the contents insurance I currently have (which has indemnity for the rented property as well).
An intentional or reckless act wouldn't be insured if it directly causes a loss, but anything else is. There's no exclusion for doing things that are illegal other than illegal substance manufacturing, and I'm pretty sure I didn't miss anything because the whole policy is 12 pages, including the cover and table of contents.
Electricity regulations wise, it's legal for me to do anything that plugs in to a socket. If I owned and occupied the property it's legal to do anything that doesn't require moving or adding a fixed cable to the consumer unit. Adding new fixed cable runs required a licensed electrician to sign them off before energising. It's illegal to do DIY electrical work on a property if it's let to anyone other than family, unless it's certified by a licensed electrician.
There is more than the policy, there is also the law and court caselaw (at least in common law countries). The policy is where they detail things not covered by the others in some way. So you need to check with a lawyer.
It's reality? Installing an L2 charger requires a permit. You don't technically have to get one, there's no county police that goes door to door checking for improper/horrible EV charging installations. However, if your house burns down, and they see you decided to jury rig your own charger from piece parts, I can guarantee you with 100% confidence they're going to tell you to pound sand when you make an insurance claim.
On the off chance your home-made charger didn't start the fire, you can spend a decade fighting them in court. But you'll probably lose.
How's that? Does plugging in a fridge require a permit? As long as the EVSE is plugged into an outlet like any other appliance, it's just an appliance. Your jurisdiction may require a permit for installing the outlet in the first place, but I've never heard of one where plugging an appliance into the outlet does.
Anyway, how many DIY EVSEs start fires? It's a glorified extension cord, not exactly rocket science, and as long as the builder applies a modicum of sense to choosing the components and wire gauges inside, and torques the connectors and stuff, there's really not much going on in there that should produce heat in the first place.
Also, this isn't a charger. It's an EVSE, there's no power electronics inside. There's a contactor, that's it, no silicon in the power path. It's really hard to screw it up.
Perhaps I'm just accustomed to the Hackaday comment section, but HN commenters are weirdly terrified of anything involving AC. It's just electricity. Not even very much of it, like, normal household levels of 240v AC. My clothes dryer uses more power, and it pulls it over wiring installed in the 1970's. Heck, when I moved, I even replaced the cord on my own dryer with one that matches the outlet in this house, an action explicitly allowed and encouraged by the access plate on the back of the appliance. The bare cords are sold at Home Depot and they come with a little slip of paper explaining how any homeowner can install them.
It's fine. It's just wire. Pick one that's thick enough, torque the screws, it's fine.
>>I’m not an electrician. I’m not allowed to make alterations to my consumer unit.
So two funny things about this in UK law - the law doesn't say who is allowed to work on your consumer unit, you can do it by yourself if you wish. What the law does specify is that the work has to be certified by a "competent person" but then doesn't actually narrow down what a "competent person" means. Local regulations might, but the UK law on this does not.
Of course - but again, the law doesn't specify that a "competent person" has to be on that list, or any list.
There was a huge debate about this couple years ago, when someone asked "can a foreign electrician certify a UK electrical installation as safe", and after very long debate the outcome was that yes, they can, because the British regulations never actually specify what they mean by "competent" and a certified electrician(even if foreign) is definitely "competent" even if not registered with any UK based authority.
You’re responding to a statement you straw-manned. The comment you’re responding implies a slippery slope, not an equivalence between DIY safety and letting kids be outside.
What? Are you op's alt-account, or did you not bother to read his response? I straw-manned nothing. He compared making your own home-charger to letting your kids play outside, not me. I simply pointed out that comparing the two was ridiculous. The fact you'd accuse me of straw-manning when I was doing literally the opposite is somewhere between hilarious and offensive.
FWIW I read it as a straw man too, and the original as a slippery slope argument rather than an equivalence. Communicating in short bits of text is hard.
Fairly certain most DIY electrical work is strictly verboten in the UK, where the author is located. I would think at a minimum you need approval from the council. Not too dissimilar to the permitting process in the US, but the UK is noticeably more safety-obsessed.
> Fairly certain most DIY electrical work is strictly verboten in the UK
No. You can't touch the consumer unit, and there's a restricted zone around bath/shower for example (by distance), but most things a homeowner might want to do are perfectly legal to DIY.
> the US, but the UK is noticeably more safety-obsessed.
Crikey, are you joking? Internet forums are awash with US concern over 'code', and to extend beyond electricity: food safety, FDA guidelines, all sorts of common senseless rubbish.
Nobody outside of the uk knows what a "consumer unit" is. that sounds to me like you can't touch the breaker panel which is what you have to touch to wire in a new circuit.
Well, there's a pretty large fraction which is still fine to do full DIY. (but not EV chargers) The next level basically either requires some certification or to get the council to inspect it, but plenty of people just ignore that.
It seems things are pretty lax in the UK. Here in Poland you need a qualification certificate to replace a broken socket and a supervisors' certificate to move it half a meter.
It isn't uncommon for people to be scared when they learn I wired my home which has a 400 amp service. I wired the previous two also. Sure electricity could kill me, burn me, burn down my house, etc., but I don't have to be the one to discover how it works. People have done that and there are building codes to follow that are build upon a whole bunch of previous failures.
We all learn different things and are at different places. I can wire my whole house and pass inspection, but I'd never take on this project, that is beyond me - but more power to him for trying. I agree, nothing wrong with some DIY that at most will go up in smoke.
I'm also a little disappointed. Yes it can go wrong, but it sounds like the author has learned a lot and listens to criticism. And clearly embodies the hacker spirit.
And I have a large number of items that either came with my house or I purchased legitimately that could absolutely burn it to the ground. It's all measured risk.
When I get an EV, I'll be adding a consumer grade charger to the house. And then I'll trust, with zero actual knowledge, that it won't burn down my house, or that my car won't.
You don’t have zero knowledge though. Most electronics sold is safe, and designs tested. So your prior for them burning down the house should be much lower than for something you diyed
Most is. But there have been two significant house fires from electrical systems in my small town in the last year.
It's also my experience that if you have the know-how, you can often do a better job than the professionals you hire, or the factory that mass-produces a product for the highest possible margins.
> I'm disappointed at the anti-DIY sentiments here, it's this safety obsessed mentality that got us to where kids can't walk outside by themselves any longer.
Except this DIY project could kill someone if it malfunctions. There are several inadequate parts of this design that make it a safety risk beyond the fire risk.
I disagree - the actual current switching electronics are off-the-shelf relays. It's more like "didn't use a GFCI or AFCI breaker where one is required, but did try to address the same safety hazard those breakers address, in a way that wasn't as good as such a breaker, but isn't totally incompetent"
> the actual current switching electronics are off-the-shelf relays
So? The system that controls the relay (with logic to prevent exposed high-voltage contacts while the car is unplugged, or danger if the cord is damaged or immersed in water) is just as safety-critical as the relay itself.
> "didn't use a GFCI or AFCI breaker where one is required, but did try to address the same safety hazard those breakers address, in a way that wasn't as good as such a breaker
Stop right there. What you describe is automatically incompetent, all by itself.
Seriously, don't do this ever. There are extremely good reasons why anything but certified, unmodified hardware is illegal to install in electrical wiring. There are equally good reasons why you can't omit required safety hardware, even if you "tried" with something else.
I disagree though, DIY circuit breakers actually could burn down your house, which I think is a step up from this project. It's like a DIY kernel file system driver vs. DIY bittorrent client.
If you put something like this in your garage and you get it wrong (despite using the right components), you can cause an electrical fire. Burning your house down seems quite possible.
But I appreciate he didn't put this in his garage. However, even hooking it up to the CU is not something some random guy should be doing: https://www.speakev.com/threads/a-cautionary-tale-of-severe-... (this one was probably due to not-adequately tightening the terminals, would you even think/know as a DIY'er?)
It feels depressing until you realize the set of all things that you can DIY that you can't buy is infinite. Factor in that the things you can buy are extremely cheap when you factor in your time, due to mass production. So it doesn't make sense to spend time building something you can just buy.
I just think it's a good principle that someone older than me shared with me a long time ago, in an electronics hobby store that no longer exists, when I was buying parts to build a bench power supply, though I had to discover some reasons the hard way.
I thought they were being an ass at the time, so I plowed ahead with my project, and realized halfway thru that this project was pretty dumb and I should have just bought one and moved on to a better more interesting project.
2. If it's outdoors, at least spray the electronics with Fine-L-Kote or similar to keep water vapor out.
3. Those relays look undersized for the load. Look at Grainger for similar ratings. Do not buy power relays on eBay or Alibaba. Current ratings there tend to be wildly exaggerated.
4. Er, overcurrent protection? An approved circuit breaker?
He says he installed a 50A OCPD, which is the same overcurrent protection an electrician would install and used relays from TE Connectivity (a respected brand) rated at 125% of the current the EVSE advertises as available. Both of those decisions seem perfectly sane/safe to me.
Are you an EE with a specialty in power electronics? Cause that seems insane to me, inductive loads will cause a voltage spike (flyback) when disconnected, which will exceed that easily. That is why there is generally a reverse diode across the contacts, which I didn't see in the diagram.
Granted the article notes it appears to be largely a resistive load, but I would want data sheets on the car/charging requirements, not measurements, to ensure this is true 100% of the time. Maybe the car has an AC compressor or a pump to cool the battery during charging, which draws directly from the charger when plugged in. You might not see that doing a few random measurements because it turns on only after some time or if someone is sitting in the car.
No, but I'm a mechanical engineer who's taken a subset of my uni's EE curriculum, done a fair amount of hobby electronics, read a lot about the SAE J1772 charging standard that applies here, and disassembled two commercial EVSEs (all in contemplation of building my own EVSE, which I haven't pulled the trigger on yet).
It turns out that the engineers who designed J1772 thought a fair amount about how to handle the connect/disconnect concerns that you raise (via the pilot signals and proximity microswitch) and they didn't just leave it to EVSE designers to YOLO it.
> I would want data sheets on the car/charging requirements, not measurements, to ensure this is true 100% of the time
The "datasheet" that you want is the J1772 standard. There are many free summaries of it, including https://openev.freshdesk.com/support/solutions/articles/6000... Scroll all the way to the bottom and read the section on "Proximity" to understand how the relays are not disconnected while large currents are flowing.
>Maybe the car has an AC compressor or a pump to cool the battery during charging, which draws directly from the charger when plugged in
No it doesn't. A/C compressors in EVs are 3 phase AC powered by an inverter supplied by the traction battery.
The contactors in an EVSE open and close at practically zero current, the OBC ramps the current up or down accordingly. And as another sibling comment noted, the OBCs are PFC corrected and act as a largely resistive load.
I used significantly higher-rated omron relays in a project I did a few years back to switch a 2.5HP motor on/off a few times daily. This area shouldn't be skimped on; relay contact arcing isn't a joke.
This brings me to my second point: I don't see a cycle rating on those relays from the datasheet provided. Most relays are rated for ~1M cycles, some for ~10M or more, but beyond that solid-state relays start to be a thing. And so, I question if people are using mechanical relays to chop 50/60Hz AC power, which from my 30 seconds looking at the article/schematic appear to be what is happening here... That seems crazy to me, and I imagine it requires some exotic contacts in the relays to avoid failure in short order, which these relays don't appear to be. The data sheet mentions they are used for chargers/solar inverters/etc but that doesn't mean they are used at 50/60Hz cycling but likely just as a disconnect/power on function which cycles once per charge/day/etc.
Then again, I don't really want to be this guys neighbor since chopping an AC line with that much load is going to generate an insane amount of noise, and I don't see anything in the circuit designed to damp it either.
Disagree with the fire risk comments, even if it burns it's outside in a suitable enclosure.
The real problem here is DIY RCD with microcontroller in the loop. The soldering on the high voltage wires is absolutely horrendous and if those come loose and the enclosure or chassis becomes live you are trusting your life on the atmel interrupt delay and software. Good luck!
More like a DIY arson investigation. You might not only burn down your house, but also get in trouble with the law and not receive compensation from your property insurance company. This is a horrendous idea. Just do basically anything else DIY besides high current/voltage electronics.
Page is hugged to death right now but I strongly disagree with parent. I'm an EE and I'm quite familiar with the National Electric Code. I build high current/voltage devices and I've wired two houses (both of which passed inspection).
If you're trained, experienced, and generally know what you're doing there's nothing wrong with working on high power electronics.
To be honest, I think the guy learned more than most electrical contractors actually know or care to check when it comes to the EVSE. I certainly would object if he is selling this or installing on other people's houses, but this looks actually acceptable for now. The longevity is a big question, since usually there's no easy way to check / test that with a singleton bespoke design/build, and that's sometimes what distinguishes the one-off vs mass manufactured stuff, albeit in both directions. Sometimes a bespoke design misses some subtle design choice and it breaks down sooner, but sometimes you can do a lot more careful handcrafting and "simple" over-engineering with a bespoke singleton to make things last even longer than mass produced stuff. I think the mechanical and the environmental aspects - condensation, thermal expansion, etc - are probably the biggest question mark here.
240v is not high voltage come on, in most European countries you don't need a permit / can DIY yourself electrical circuits and they're all 240v. It's hard to burn down your house with electricity, breakers are pretty good at what they do.
This is such a bad DIY project because the costs of screwing up can be burning your house down. This is non-trivial amounts of power. If you spend the money fot an EV, buy something safe and have it professionally installed. Keep the DIY projects to something less dangerous.
TBH I’m less concerned about dangerousness… but the costs listed are so much, whereas commercial EVSEs are so cheap. You can buy a 40A 240V capable EVSE for like $200-300. The OP says they bought the cable for $120… why not just have the rest of it for a small additional cost?
It is surprising to see this question on HN. We regularly see Show HN projects that cost tens of thousands of dollars in time (assuming a typical software engineering hourly rate), but that aren't all that innovative compared to existing options. And we love those projects. Why would DIY effort outside the software domain be any different?
I don't think this is a valid comparison. In DIY projects, your time is free: you don't count your engineering hourly rate as part of the cost of building the thing. The only cost is the actual costs incurred, which is mainly parts and materials.
So a Show HN project that's purely software effectively is worth $0, because the creator made it in their free time, instead of spending that time playing video games or watching TV or whatever. And a Show HN project with a lot of software running on a RasPi effectively costs only what the RasPi cost the author.
Here, people are complaining about the actual hardware cost to the creator, not the creator's time spent, which you're also ignoring.
When I was 20 years old, I would have agreed with your position. But that was a long time ago.
Everyone, no matter how materially wealthy they are, gets 24 hours per day. That time is, by definition, 100% of the time that you'll get, which means that its value (intrinsic) is nearly infinite. This is true even if its price (extrinsic) is zero.
My point in mentioning an engineering rate was not to quibble about what free time costs. It was to say that even if someone confuses price with value, we can agree the the value gained from time well spent is very high. So it seems strange to criticize a hardware project that had $X of "hard" costs, $Y of "soft" costs, and $Z of benefits, when we regularly admire software projects that are valued identically, except that $X is close to zero. $X + $Y + $Z = a huge net positive value (judging from the number of HN comments and votes, as well as the pride that OP shows in the writeup). For many of these Show HN posts, it doesn't matter if $X is $300 or $0; the math still evaluates to awesomeness.
I'm not sure I follow. My criticism is in trying to value projects in term of engineering time. I don't think that's valid at all. Free time is worthless, except to the person spending it. It's not like I'm going to spend my free time doing more work for my company and make that much more money at an hourly rate: I'm salaried, so extra time spent is just a gift to the company with the vague hope I'll get some bonus or promotion. Plus, for mental health I have to take breaks from work and do something different, which could be reading a book, watching a movie, or working on a personal project completely unrelated to work. Either way, I'm not counting that time in terms of an hourly rate; I think that whole concept is just insane. I don't think of the time I spend on the toilet or making dinner in terms of an hourly pay rate, so why would I do that for a personal project? The only cost to me to pursue a hobby is in the materials needed.
My mistake was using typical prices for engineering work as an attempt to establish a baseline understanding that we all agree free time is very valuable. I can see how that's become a morass in this discussion.
I value my own free time much more highly than I do my employment time. I would prefer to have more free time than employment time. So if employment time's going rate is $X, then a dollar value of free time must be higher than $X. No, I don't expect people to pay me for my free time. But I do think it's healthy to think of free time as the most valuable time someone can have. Not the highest price but the highest value.
This is why I think it's wonderful to see projects on HN where we find out how our fellow geeks are spending their most valuable time. And it bugs me that people sometimes respond that someone could have bought the same thing for less money or less time.
Ironically, we both object to putting a price on time, but I believe our objections are in opposition to each other.
Yeah, I think we're agreeing but in different ways. I think of my free time as mostly worthless to others, but infinitely valuable to myself, so I refuse to put a dollar value on it.
And sure, I agree that it's nice to see people spending their most valuable time doing something they enjoy, in this case interesting projects.
But as I've said elsewhere, personally, I wouldn't spend my time making a copy of something I can just buy a better version of cheaply elsewhere; if I'm going to spend my time on a project, I'd rather spend my time doing something different, like something new or a customized version of something, which I can't easily buy. But it's not black and white; I'll happily spend my time fixing my bike instead of paying someone to do it, for instance. (Of course, paying a professional might take more time once you consider how long it takes to bring the bike to them, and then wait a week for them to get to it...) I like fixing things like that, so for me it's enjoyable.
Software projects have portability; you spend X amount of time, and others can use your labor for free or nearly free.
In comparison, hardware projects have costs even if the 'hard work' is done: PCBs to buy, components to assemble, parts to purchase. Even BEST case here, and discounting peoples time, it looks like the cost of all the components listed would be in the neighborhood of $200. And that assumes you can source the same 'demo' cable that the OP purchased for the same cheap price. Realistically I bet actual costs would be $300+
I have nothing against DIY hardware projects, the problem is that hardware projects must pass a much higher bar: you have to be cost competitive at a minimum with existing products on the market, or you need to be better in some way (and, that way can be trivial, as long as it's interesting). This appears to be neither.
Because the project makes the claim that it was to save cost. The reality is that most of the cost is in paying an electrician for the install, and since he did that part himself anyway he could have just went for an off-the-shelf certified charger.
It looks like all he’s doing is switching mains voltage, so it doesn’t seem that dangerous. There isn’t much that can go wrong with the high-power side of this system.
I love higher power DIY stuff in general, but yea this project really doesnt thrill me. It does sound like the author did adequate research, which is good, but the soldering joints dont inspire a ton of confidence in overall quality.
Stuff like this is absolutely what I would consider "worth" paying a professional to do. Especially since buying a retail unit/paying a professional to install it will come with warranties.
Some of us here are actually Engineers (Electrical).
I’ve installed 3x 240V 60A EV chargers, was a cakewalk. I didn’t build my own in this case since I was going for an aesthetic match.
Meanwhile you can enjoy paying some alcoholic $1000 for 30 minutes of work to:
* pop out a hole on the back
* Tap and install 2x screws into studs
* pull 3 wires 6” through, wrap around the strain relief, strip/insert/torque
* flip a breaker
It’s not rocket science, as long as you’re not a complete idiot and turn the breaker off before hand it’s completely safe. 240V isn’t even “high” voltage.
I've hired enough licensed, bonded, certified, well-recommended, well-reviewed professionals who completely botched the jobs* to agree wholeheartedly with your sentiment. You can't hire someone without thoroughly understanding what they're doing, and once you reach that level of understanding, you absolutely can make an intelligent decision whether to buy or build. At the point where my house burns down, I really don't care about the credentials of the person who made the mistake. Rather, I personally make sure my house doesn't burn down.
* Solar panels installed facing North in the Northern Hemisphere; rapid-shutdown switch installed inside a home; supply side of 240v connection to backyard office has male prongs; fence built with non-pressure-treated wood contacting the soil. The list goes on, and these are only the errors I've discovered in 20+ years of being a homeowner.
If only it was just the tradespeople. I've had an electrical inspector argue that I should route the ground from my windmilltower into the house and bond it to the distribution panel rather than to ground the windmilltower at the base of the tower.
So in case of lightning strike (which is pretty much a given) that would invite that lightning into your home right at the distribution panel. People may be following 'the code' but that doesn't mean they actually understand what they are doing. He wouldn't take responsibility for it, I asked him to put it in writing as an instruction and sign off on it so I could pass it to my insurance company. That never happened...
I don’t know the whole setup, but the inspector is likely right. When you have a feeder to an outbuilding (or external structure or piece of equipment or subpanel or basically anything else), you supply it with the intentionally current-carrying wires and the ground. (Ground may be called “equipment grounding conductor” or “protective earth” or perhaps something else in your jurisdiction. It’s a wire or the metallic conduit you used.)
And this is important for lots of reasons. If there is a fault from a hot wire to a grounded object, this (if done correctly) allows the upstream overcurrent protection to trip. And it minimizes the voltage rise of the object that gets energized. And it keeps the line-to-ground voltage within spec. And using a separate ground means that the voltage of “ground” doesn’t get pulled up by resistance in the neutral wire and that current doesn’t normally flow through “ground”.
You should, of course, also connect the ground wire to Earth, well, at the base of the structure. And possibly also install something to help conduct lightning currents from the non-ground conductors to ground in the event of a lightning strike.
> I don’t know the whole setup, but the inspector is likely right.
That's an interesting start to your comment. So you don't know the whole setup but you do know the inspector is likely right.
Well: if he was likely right he would have not shied away from putting it in writing. What happened was that halfway into the conversation he realized he was wrong, hightailed it out of there and simply didn't want to admit that he was wrong.
I do know the whole setup. And I have spent enough time installing high stuff made out of metal (mostly: antenna masts) to know that the last thing you want is to give lightning a short path into your dwelling.
His whole experience seemed to be based on simple domestic installations, and instead of just admitting that he didn't know exactly what to do and to go look it up or ask someone more experienced to look it over he dug in. Human nature, I get it, but this is safety we're talking about and the amount of flak the OP is getting in this thread from people that likely have more experience with keyboards than with real world engineering is telling. Just like you: they don't know the whole setup but they'll argue that it is unsafe, will void your insurance, will get you investigated for arson(!) and might kill your kids.
You last paragraph is exactly the problem: he outright forbade me to ground at the base of the tower because that was in his opinion unsafe. But it wasn't his life and property that was at stake.
I've seen up close what lightning will do to various pieces of gear, it isn't pretty, to put it mildly and you make sure you keep it as far away from your house as you can. And have spark gaps to ground at the point of entry for your power cable, just in case.
Finally: the proof of the pudding is in the eating. When after a year we pulled the tower down again there was evidence of multiple strikes on the nacelle body at the top of the tower, all of which were dealt with gracefully, to the point that we didn't even realize the machine had been hit. What helped is that for the whole installation we had a massive amount of help from an experienced wind turbine vendor who took an interest in our project.
> you supply it with the intentionally current-carrying wires and the ground
Whether you connect both grounds to both themselves and Earth, or just connect both grounds to Earth, or connect them to Earth once and connect them both depends on so many details, it's not funny.
What is certain is that you don't want something that doubles as a lightning rod protected on the same internal circuit as your house. So your rationale doesn't apply to the GP.
But anyway, every time somebody talks about electrical installations on the internet, somebody says some version of "If there is a fault from a hot wire to a grounded object, this (if done correctly) allows the upstream overcurrent protection to trip." Is it still a recommended practice on the US to rely on overcurrent protection to protect against current leakage? It's an horrible practice, as it requires several amperes of leakage before triggering.
> Is it still a recommended practice on the US to rely on overcurrent protection to protect against current leakage? It's an horrible practice, as it requires several amperes of leakage before triggering.
Yes.
I don’t agree with it, personally — I think that there should be standard ground fault trip curves that are functions of circuit breaker rating such that they coordinate properly, and that they should be used at least on all circuits that extend outside of a building and really on most circuits, period. This would add costs, and it would detect and thus prevent a lot of dubious wiring practices and outright errors.
But you should still bond all your “ground wires” together so that even if these breakers fail to trip you have a degree of protection. (And breakers do fail.)
Under current NEC (the US code), when you supply a building with a feeder (i.e. from another building or similar structure), you must provide it with all the current carrying wires and separate ground, and you must ground it to the Earth.
In any case, if you live in a place where your utility supplies power above ground, and a utility pole or line is hit by lightning, its ground is most certainly solidly connected to your house. So you can’t really pretend that your house’s ground is connected only to the Earth near your house and that it won’t let lightning in.
Hmm, I wonder if you can take the ground wire running between two buildings and carefully insulate it and give it a wrap or three around a piece of steel to add some inductance and reduce lightning currents that might otherwise go through it. I’m not saying this is wise…
Indeed. We had proper ground fault protection breaks for that purpose, and it was really hard to get them.
That + the use of metal tubing to carry electrical power as well as the incredibly flimsy construction of various sockets and such (as well as the high amperage) translates into lots of preventable fires each year in the USA and Canada. Point a FLIR at your average distribution panel and try not to be amazed at the number of hot spots.
My biggest gripe: I don't mind inspectors, I just expect them to be really knowledgeable, not just theoretical. Grounding a structure is inherently different from grounding a circuit. He basically kept on insisting that the windmill is part of the circuit and should be bonded rather than that it had its own ground and that is just patent nonsense, more so because the windmill produced variable frequency AC that first had to be rectified, passed through a battery charger, a bunch of batteries and an inverter. The latter of course was bonded to the house ground.
Outside is another matter. Those galvanized steel tubes don’t last very long underground, and the results are terrifying. And nothing in the code requires ground fault protection upstream of a 120V circuit running through a corroded steel tube underground.
They conduct electricity. Thus if you have a leak from one conductor somewhere in your house (that without ground fault protection goes undetected almost every case) and gets a different one from a different wire, you now have a constant-on heater passing through God knows where, ready to start fires.
A single leak also gives you a minor risk of electrocution. But the fire hazard is the important one.
This is possible with nonmetallic conduit, too, as well as with NM-B. At least metallic conduit has a decent chance of containing the resulting mess inside the conduit.
The right solution is ground and arc fault protection, both of which are available, and one of which is increasingly required in the US.
You seem to be thinking about short circuits. That's not what my post is about. (Anyway, plastic conduits are quite capable of containing the mess.)
And yes, they are way less dangerous if you have ground fault protection. To the point that I'm not sure it's still important to ban them. But they don't have any upside either.
I think metal conduits are most useful in more industrial-ish spaces where they're exposed -- they're quite resistant to getting banged up. Schedule 80 PVC works, too, but it's harder to work with than steel (at least for an electrician with the right tools).
First, it’s a bit more complicated than that—unless you went ahead and installed a 60A line without checking if your service(s) can handle the additional load. Advice like this is what gets people to screw up.
Second, what’s the material difference between a 40A circuit and a 60A circuit? A few extra hours overnight to charge?
Well, there are times when you're not charging overnight (e.g., get home with low battery, realize you only have 3 hours before next outing) and you get 50% more charging done in the same time, without having to go out to a Supercharger / DCFC.
Or, as in our case, we have two EVs - speed is useful sometimes.
Actually one 60A and one 40A. We have a 100A subpanel in our garage. Having them asymmetric (vs 2 x 50A) means that if we need one specific car to be charged as fast as possible, we can.
The control pilot PWM signal at maximum duty only gets you 32A (~7kW). It doesn't matter how much the circuit breaker is rated for; the car isn't going to draw appreciably more than 32A. Higher charging currents are instead handled by distributing it across multiple phases. For example, a 3-phase 230V EVSE will give you ~22kW.
EDIT: Even-higher-still vehicle charging is handled by having a charger outside of the vehicle and feeding the vehicle with DC, which is what e.g. Tesla Superchargers do.
You're 100% right, but it not being "high voltage" is totally negated by the fact that the two legs together will kill me if it seeks ground via the right (wrong?) path for sure.
I know a few electricians, and none of them would agree with you. There's some things that can't be done safely on a live panel, but there are some things that can.
It's very hard to imagine any electrician advising a DIY homeowner to install a 240v line on a live panel.
It's not difficult to do, which was GP's original point--though you need to take safety precautions (in addition to researching local code requirements).
My point is that electricians work in live panels all the time. (And the voltage of the circuit being installed does t matter. No matter what you install, the panel has 240V with approximately zero output impedance.
I don’t know what advice an electrician would give, but the advice I give is that if you don’t feel like you can safely install a new circuit on a live panel, you probably just shouldn’t install new circuits.
I currently also did my own DIY EVSE charger mainly for fun [1].
If you are interested about the main differences between your approach and mine:
(1) I use an industrial contactor DIN form factor for the power switch instead of passing the power through the relay directly. Mainly for safety reasons (I do not trust much small relays) and also because I wanted to support three-phase power for an European T2 installation.
(2) Instead of printing my own PCB with an Arduino for the PWN, I just bought one command module from China/UK provider. Mainly for pure lazyness reason :) The module itself is shield behind the RCD class B.
(3) I have added a shelly 3EM front of the system. To use it as a watt-meter with MQTT report and also as a remote control system.
My little advice for people interested to do their own: DIY is always an excellent way to learn and if you want to do your own, do it... BUT please make your installation reviewed by someone with an electrical engineering or technician background if possible. These systems can easily pump 7 to 22KW during extended period of time: Any cable which is not screwed properly or under-sized can bring you a fire.
[1]: https://github.com/adevress/open-ev-station/blob/master/READ...