I used to work in a rather well-known building running the electronics operation and we had long PVC conduits that contained communication cables that ran large distances throughout the building and both the conduits and cables were attacked by rats.
The main conduits were about 15cm (~6") in diameter and the total CSA of the comms cables therein occupied about 40% of the total diameter.
40% of the total CSA was the nominal/regulated maximum cable-carrying capacity for the conduits as (a) drawing cables through long conduits in excess of this limit could damage them, and (b) there was still some small margin/extra capacity should there be need to add a few extra circuits.
Now rats quickly discovered that the remaining 60% of space in these conduits provided them with excellent 'highways' from one end of the building to another.
As one would expect, cables would also enter and exit these conduits at various points throughout the building at 'T' junctions. The adjoing conduits at the 'T' junctions were often of much smaller diameter than the main trunk ones and rats had difficulty getting though their small orifices so they simply enlarged them by gnawing through both the conduit walls and the comms cables.
Many of the cables were PVC covered and EMR shielded such as RG-59 coaxial cable and Belden Beldfoil-type balanced comms cables and there were many cases where both the copper braiding/outer shielding and inner conductor of the coaxes and the aluminum shielding of the Belden cables were completely chewed through. It seems that PVC, mylar, copper and aluminum are not objects that act as impediments to determined rats—anything in their way they'll chew right through.
Trouble was these points of ingress and egress were in very awkward places and repairing the cables was a tedious and difficult job.
Somewhere in my archives I've photos of the havoc and destruction they caused, if HN would also post images then I'd dig them out.
Incidentally, I've seen photos of lead-sheathed (completely covered and shielded) telephone cables consisting of hundreds of phone circuits where rats have gnawed right through the lead to get at the paper insulation on the cables. Some of these photos are quite amazing, it's hard to believe how destructive these rodents can be until one actually sees the evidence.
Chewing through lead! How do they know something is worth it on the other side? Or do they like sweet metal?
For the unaware, lead tastes sweet. Kids used to eat lead paint chips. And there have been sweet springs of great tasting lead water. Hmmmm forbidden springs
"Chewing through lead! How do they know something is worth it on the other side?"
I wish I knew, it's something I've been curious about since I first saw the photos. Perhaps it's because lead can taste sweet, or there's residual smell on the outside of the cables, or maybe they've learned from elsewhere where the telephone pairs exit the main cables.
Incidentally, it's a long time since I've seen those photos but I vividly remember them as it seemed so strange. I'm almost certain the photos were in the Electrical Engineering Supplemently Volumes of the Newnes Encyclopedia. (The exact name(s) of the supplemently volumes could be slightly different, memory's short given the length of time since I've last seen them. BTW, I think there were four supplemently volumes.)
The main conduits were about 15cm (~6") in diameter and the total CSA of the comms cables therein occupied about 40% of the total diameter.
40% of the total CSA was the nominal/regulated maximum cable-carrying capacity for the conduits as (a) drawing cables through long conduits in excess of this limit could damage them, and (b) there was still some small margin/extra capacity should there be need to add a few extra circuits.
Now rats quickly discovered that the remaining 60% of space in these conduits provided them with excellent 'highways' from one end of the building to another.
As one would expect, cables would also enter and exit these conduits at various points throughout the building at 'T' junctions. The adjoing conduits at the 'T' junctions were often of much smaller diameter than the main trunk ones and rats had difficulty getting though their small orifices so they simply enlarged them by gnawing through both the conduit walls and the comms cables.
Many of the cables were PVC covered and EMR shielded such as RG-59 coaxial cable and Belden Beldfoil-type balanced comms cables and there were many cases where both the copper braiding/outer shielding and inner conductor of the coaxes and the aluminum shielding of the Belden cables were completely chewed through. It seems that PVC, mylar, copper and aluminum are not objects that act as impediments to determined rats—anything in their way they'll chew right through.
Trouble was these points of ingress and egress were in very awkward places and repairing the cables was a tedious and difficult job.
Somewhere in my archives I've photos of the havoc and destruction they caused, if HN would also post images then I'd dig them out.
Incidentally, I've seen photos of lead-sheathed (completely covered and shielded) telephone cables consisting of hundreds of phone circuits where rats have gnawed right through the lead to get at the paper insulation on the cables. Some of these photos are quite amazing, it's hard to believe how destructive these rodents can be until one actually sees the evidence.