Can Squirrels Damage Electrical Wiring in a Loft?

Why They Chew Cable Specifically

They do not target it. A squirrel’s incisors grow continuously and have to be worn down, so it gnaws whatever is available — and in a loft, cable runs across joists at exactly the right height and has a satisfying resistance.

PVC sheathing is soft enough to strip easily and firm enough to be worth working on. From the animal’s point of view it is ideal. From yours it is the worst thing in the room for it to have chosen.

What the Actual Risk Is

Stripped sheathing exposes conductors. Two exposed conductors touching, or one touching a metal fixing or a pipe, can arc. An arc in a loft full of insulation, dry timber and stored cardboard is how loft fires start.

Damage to a cable can also raise resistance at that point, which produces heat under load without ever tripping anything. That is the version people do not expect, because everything appears to work normally.

Why "The Lights Still Work" Proves Nothing

A partially damaged cable carries current perfectly well. Circuit protection is designed for overload and earth faults, not for a cable that has been shaved thin at one point on a joist.

So the fact that nothing has tripped is not reassurance. If a squirrel has been in the loft for any length of time, the wiring needs looking at whether or not anything has misbehaved.

What to Do If You Find It

Do not touch it and do not try to tape it. Get an electrician to inspect and repair or replace the affected runs once the animals are out. It is not usually a large job, and it is not one to put off.

Deal with the squirrels first, or the new cable gets the same treatment. This is a £280 trapping service with legal duties attached — grey squirrels cannot lawfully be released once caught — and it comes before any repair work.

What Else in the Loft Is at Risk

Plastic water and soil pipes, which produce leaks rather than fires but cost more to put right. Aerial and data cable. Alarm and boiler wiring. Anything plastic, essentially.

And insulation, which gets shredded, compacted and soiled. Once it has been used as a latrine it should be removed and replaced rather than left, both for the smell and because it has stopped doing its job.