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Can Squirrels Cause Electrical Fires? Yes, and They Do

Gnawed cable insulation is a documented ignition source in roof spaces. Why they chew wires, the warning signs, and the metal mesh that stops it.

By Salma 3 min read Save to Pinterest — opens Pinterest in a new tab
A bundle of old taped cable with exposed conductors at one end
Photo: Luminas_Art, Pixabay Content License, via Pixabay
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Yes. Gnawed cable insulation is a recognised ignition source in roof and wall voids, and squirrels are among the worst offenders — large, strong-jawed, and chewing because they have no choice.

Why it happens

A squirrel’s incisors grow continuously — in the region of six inches a year — and are worn down against hard material. A bird that stops gnawing develops malocclusion and starves, so this is maintenance rather than mischief.

Cable is simply convenient:

  • The right hardness to wear teeth down
  • Routed along the beams and voids squirrels already travel
  • Plastic sheathing gives easily under rodent incisors
  • It is there, in a space the animal is living in

There is nothing attractive about the electricity. Squirrels are not drawn to live cable; they are drawn to roof spaces, and cable is what is in them.

How a chewed wire becomes a fire

  1. Insulation is stripped, exposing the conductor
  2. The exposed conductor touches another conductor or a joist
  3. Arcing generates intense local heat
  4. Dry insulation, stored boxes and timber are immediately adjacent
  5. The fire develops in a void nobody is looking at

That last step is why roof fires are serious out of proportion to their ignition energy — nothing is noticed until it is well established.

If you find chewed cable, get an electrician before anything else

Damaged cable is a live hazard whether or not the animal is still there. Have the circuits inspected before you deal with the squirrels, not after. And do not go poking at exposed wiring in a roof space yourself.

The warning signs

signwhat it means
Scratching and running overhead in daylightgreys. Night noise is rats, mice, raccoons or flying squirrels
Droppings and urine staining on insulationactive occupation
Strong ammonia smellestablished, probably with young
Insulation shredded into a nestnesting
Gnaw marks on joists, fascia, cablethe damage in progress
Grease marks round a gapthe entry point
Lights flickering, breakers trippingpossible cable damage — treat as urgent
Daylight visible from inside the roofan opening to seal

Sealing it properly

Exclude first. A one-way door over the main entrance, every other gap screened, three to five days, then a paper-stuffing test to confirm the space is empty.

Then seal, in metal.

  • Heavy-gauge welded mesh or sheet metal at every opening. Plastic, foam and timber get chewed straight through
  • Roof-wall junctions, soffit returns, fascia gaps, gable ends, vent covers
  • Chimney and flue caps
  • Look for gaps about the size of a golf ball — squirrels enlarge anything smaller

Then remove the access:

  • Prune branches back about 10 ft from the roofline. Squirrels jump 6–8 ft
  • Downpipe guards and smooth bands on posts
  • Move bird feeders 15–20 ft from the house and sweep the spill

Timing

Do not seal between roughly February and April or August and October without checking for young. Walled-in kits die in the cavity, which turns a sealing job into opening a ceiling.

The insurance question

Most policies exclude rodent and vermin damage, treating it as maintenance rather than a sudden event. There are sometimes exceptions where the animal causes a covered peril — a fire being the obvious one — so it is worth reading the wording and asking.

What you should not do is defer the repair on the assumption it will be covered. The cable is the hazard; the argument about who pays is a separate conversation that can happen afterwards.

Common questions

Can squirrels really start house fires?

Yes. Rodents gnawing through cable insulation are a recognised ignition source in roof and wall voids, and squirrels are among the worst offenders because they are large, strong-jawed and persistent. Stripped insulation exposes conductors that can arc against each other or against a joist, and a roof space full of dry insulation and stored material is close to ideal for a fire to take hold unnoticed.

Why do squirrels chew electrical wires?

Their incisors grow continuously throughout life and must be worn down or they overgrow, so gnawing is constant and not optional. Cable happens to be the right hardness, it runs conveniently along the routes they travel, and the plastic sheathing gives easily. There is no attraction to the electricity itself — the wire is simply there and chewable.

What are the signs of squirrels in a roof space?

Daytime scratching and running overhead, because greys are diurnal — night noise is usually something else. Then: droppings and urine staining on insulation, a strong ammonia smell, shredded insulation pulled into nests, gnaw marks on timber and cable, grease marks around an entry hole, and intermittent lighting or breakers tripping for no clear reason.

What should I do if I find chewed wiring?

Treat it as urgent. Get an electrician to inspect the circuits before anything else, including before the squirrels are removed, because damaged cable is a live hazard whether or not the animal is still there. Then exclude the animals and seal the building properly, since repaired cable in an unsealed roof is simply waiting to be chewed again.

Does home insurance cover squirrel damage?

Usually not. Most policies exclude damage caused by rodents and vermin as a maintenance matter rather than a sudden event. There can be exceptions where an animal causes a specifically covered peril, a fire being the obvious case, so it is worth reading the policy and asking your insurer — but do not plan on being covered for the chewed cable itself.

How do I stop squirrels getting into the roof?

Seal every opening with heavy-gauge metal mesh or sheet, never plastic or timber, after excluding the animals with a one-way door. Then cut the access: prune branches back about ten feet from the roofline, fit guards to downpipes, and move bird feeders well away from the house. Do not seal between roughly February and April or August and October, when unweaned young may be inside.

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