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.

What’s wrong with metal tubing indoors?

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).

Indeed, they are useful for exposed installations.

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.

So you installed 2 60A circuits?

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.

Don't work with a live panel.

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.