Symptoms
- Chew marks or gnawed insulation on visible wiring
- Signs of mice or rats nearby: droppings, nesting material, gnaw marks on other materials
- A circuit that trips intermittently for no clear reason
Likely causes
- CommonMice or rats nesting in an attic, crawlspace, or wallRodents chew on wire insulation as part of normal gnawing behavior and to build nests.
- PossibleLong-term rodent activity that's gone unnoticedDamage often exists in more places than the one wire you found.
- CommonEntry points near the home's exterior letting rodents into wall and attic spacesGaps around pipes, vents, and the foundation give rodents access to areas where wiring runs.
What to do
- Avoid touching any wire you find with visible chew marks.
- Turn off the breaker for that area if you can identify it, or the main breaker if unsure.
- Do not attempt to tape over or splice the wire yourself.
- Address the rodent problem itself with traps or pest control alongside the electrical repair.
- Have an electrician inspect the full run of wiring in that area, not just the spot you found.
- Ask about wire protection options, like conduit, in areas prone to rodent activity.
- Seal up entry points rodents are using to prevent repeat damage after repairs are made.
When to call a pro
Call a licensed electrician to inspect and repair rodent-damaged wiring, and a pest control service to address the rodent problem itself.
Safety
Use caution
Don't touch or attempt to repair chewed wiring yourself; a compromised wire can be live and can also start a fire. Have it professionally inspected and repaired.