There are two places in a South Louisiana house that nobody looks at: the attic above you and the crawlspace underneath. Both are where the wiring quietly goes bad, and both are where we find burned insulation on a house that never had a problem anybody noticed.
Heat takes the life out of old insulation
A Baton Rouge attic on an August afternoon runs well past 130 degrees. Wire that went in during the 70s or 80s has been sitting in that for thirty or forty summers, and the plastic on it does not come through unchanged. The compounds that keep the jacket flexible cook off over time, and what is left is brittle.
Brittle is the whole problem. A jacket that has gone hard cracks when it gets disturbed, whether that is a whole-house fan shaking, somebody stepping across the joists to reach the air handler, or the house settling on its piers. Once it cracks, bare copper is sitting against framing and blown insulation with nothing covering it.
That is the kind of fault that does not announce itself. It waits for a damp day or a loose connection to push it over.
And then there are teeth
Squirrels, roof rats and mice all move inside when it rains hard, and their front teeth grow for their whole lives. They have to chew to keep them worn down, and the vinyl jacket on Romex is soft enough to be worth the effort.
Once they get through the jacket they keep going into the insulation, which leaves energized copper exposed inside the structure. Three things follow from that:
- Arcing. A hot and a neutral a hair apart will arc across the gap, and an arc throws sparks hot enough to light framing or the dust sitting around it.
- Tripping you cannot explain. If an AFCI breaker keeps tripping and there is no appliance to blame, chewed wire in the attic or the crawlspace is one of the first things to go looking for.
- A live house. This is the one that worries us. In a pier and beam crawlspace, a bare conductor can end up resting on a copper water line, a gas line or the metal ductwork, which puts voltage on plumbing somebody touches in the kitchen.
What we do about it
This is not a tape and hardware-store junction box repair.
- Where rodents are a problem, the wire gets armour. Flexible metal-clad cable or electrical metallic tubing over exposed runs is what stops the chewing rather than inviting it back.
- Damage gets cut out, not patched over. The bad section comes out and the splice goes into an accessible metal box with proper connectors, keeping the ground continuous. A splice left open in an attic with tape over it is a fire waiting on a bad day.
- In a crawlspace, the wire goes up, not down. Runs get fastened along the sides of the floor joists instead of hanging underneath them, which keeps them out of the damp and out of the way of anything crawling through.
Common questions
Can I just wrap the chewed part in electrical tape? No. Tape does not restore the rating of the factory insulation, it does nothing about the next set of teeth, and a splice outside an accessible box is not a legal repair.
How would I know before something burns? Watch for a burning plastic smell near ceiling fixtures, an AFCI that keeps tripping with nothing plugged in, flickering that follows one circuit rather than the whole house, and outlets that have gone dead in a single room. Any of those on a Denham Springs pier and beam house is worth an inspection rather than a guess.
Does insurance pay for rodent damage? Usually not. Standard homeowner policies commonly exclude damage caused by rodents, vermin and insects, which is the practical argument for catching an infestation early instead of after the wire is gone.
If nobody has ever looked in your attic or under your house, that is the reason to have somebody look. We go through both, find what the heat and the animals have done, and put it back the way it should have been run the first time.