Mice as Fire Hazards
March 28, 2016 5:31 PM   Subscribe

Our house is 150+ years old. It's porous. Ergo we have mice. Is this an actual problem? They're not in the living areas (thank you, cats) but they are in the crawl space under the house and they are in the walls. I've heard anecdotes, of course. And you are not my electrician or my pest control professional. But do mice really chew on wiring? (If they do, why?) If they do, will they really cause a fire in a house with updated wiring and a modern breaker box?
posted by baseballpajamas to Home & Garden (15 answers total)
 
No idea about whether they're fire hazards, but their feces may exacerbate any asthma or allergy problems y'all have.
posted by aniola at 6:07 PM on March 28, 2016


Mice chew. It is really part of their nature. They chew to make nesting. To see if something is edible and if it tastes good. How much damage is variable, but cutting into a wall to make repairs is frustrating at best. A fire is worse case and can happen.

They also eat wood which could lead to structural damage. They poop, and urinate which can lead to mold problems and other bugs.

They can also die in the walls, which is gross, smelly and also requires cutting of drywall.

In summary mice are bad news.
posted by AlexiaSky at 6:09 PM on March 28, 2016 [1 favorite]


Yes, mice do chew on wiring. I had a house with a hard-wired alarm system, and several false alarms were finally traced to some chewed wiring, with incriminating mouse poop adjacent.

And then there's this (I can't not post it here):

The Country, by Billy Collins

I wondered about you
when you told me never to leave
a box of wooden, strike-anywhere matches
lying around the house because the mice

might get into them and start a fire.
But your face was absolutely straight
when you twisted the lid down on the round tin
where the matches, you said, are always stowed.

Who could sleep that night?
Who could whisk away the thought
of the one unlikely mouse
padding along a cold water pipe

behind the floral wallpaper
gripping a single wooden match
between the needles of his teeth?
Who could not see him rounding a corner,

the blue tip scratching against a rough-hewn beam,
the sudden flare, and the creature
for one bright, shining moment
suddenly thrust ahead of his time—

now a fire-starter, now a torchbearer
in a forgotten ritual, little brown druid
illuminating some ancient night.
Who could fail to notice,

lit up in the blazing insulation,
the tiny looks of wonderment on the faces
of his fellow mice, onetime inhabitants
of what once was your house in the country?

"The Country" by Billy Collins, from Nine Horses: Poems

Sweet dreams!
posted by Corvid at 6:24 PM on March 28, 2016 [28 favorites]


Anecdata: My dear pet hamster who is a rodent (a fact I frequently dismiss because my hamster is my baby and such) cheerfully chews through wiring when on the lam from her cage. She probably chews for reasons AlexiaSky states above and also for fun.

I'd imagine that mice are much the same and you'd better watch out.
posted by maykasahara at 7:30 PM on March 28, 2016


Rodents teeth never stop growing, so think of it as a teething process as well.
posted by AlexiaSky at 7:36 PM on March 28, 2016


I stayed at a crappy vacation rental where either mice or squirrels had gotten in to the space between the floors and were romping back and forth across the ceiling over my bed. And the stain in the drywall was most likely urine and was developing mold. Get the mice out.
posted by amanda at 8:50 PM on March 28, 2016 [1 favorite]


Rodents carry Hantavirus. It may not be in your area of the world yet, but who wants to take the chance?!
posted by WalkerWestridge at 8:56 PM on March 28, 2016


Even if they aren't in the main living area, they will stink up your entire house. Occasionally I open a long packed up box of stuff from my old house that had mice and I can STILL smell it on my stuff.
posted by emptythought at 9:10 PM on March 28, 2016


I grew up in an old timber-built (not framed, just a bunch of interlocking logs) house on an acre or so, and our house has always had mice, especially in winter. We humanely trap 'em and drop 'em off a large-for-mouse distance from our house so they don't come back. They have chewed through no electrical wires in my lifetime, though this also may be due to the less accessible wiring in a timber house, but one did chew through a wire under our dishwasher, where he promptly became a link in the circuit and fried himself to death by electrocution. He was very singed when we found him a few weeks later because our dishwasher stopped working and also he was stinking up the place.

So yes, they do chew, and I could definitely see it causing a fire. BUT. you may just have to be vigilant about trying to catch them and move them out, because in my experience, old houses cannot be mouse-proofed, realistically.
posted by euphoria066 at 9:24 PM on March 28, 2016 [1 favorite]


Best answer: My experience is while mice will definitely chew on wiring it isn't really a wide spread problem with the exception of some select versions of loomex/NMD that were made and/or lubricated with vegetable oils. Mice and rats loved that stuff and would completely strip the jackets but if you had that you'd already know.

Otherwise mice chewing on wires seems to be more isolated to the occasional bit mostly at penetrations (holes in walls or studding) where the mice were using the hole as a door/tunnel. The mice end up chewing through the wire making the holes bigger.

Your mice/area may differ.

A modern panel with Arc Fault breakers on most circuits will minimize most of the risks of fire induced by wires laid bare by insulation degradation from any source. It won't eliminate the risk though as not all arcs/shorts will trip a breaker.

If you were doing a down to the studs rewire and were especially cautious one could elect to run your circuits in an armoured cable (BX/AC) or ultimately in EMT. It would be pretty cheap to have an electrician come by and inspect the crawl space wiring.
posted by Mitheral at 9:55 PM on March 28, 2016 [1 favorite]


I have a mouse house. Old house, edge of wooded land, and can't figure out how they are getting in. Both myself and the exterminator have scoured every inch of the house and cannot determine how they are getting in, but they do. Mouse man comes once/month to keep them from setting up shop. But now I have a new thing to keep me up at night, wondering if the mice will cause a fire.
posted by archimago at 4:06 AM on March 29, 2016 [1 favorite]


You can't live with mice. Call an exterminator. Yesterday.
posted by Ruthless Bunny at 6:52 AM on March 29, 2016 [1 favorite]


Absolutely invest in eliminating the mouse infestation: Aside from any putative fire risk, they carry other vermin and disease, and are profoundly unsanitary housemates.
The idea that there are mice present in or adjacent to your house that are not entering living spaces is utterly ridiculous. Even if you have Navy Seal/British SAS level mouse hunting cats, those wee swine are getting into your cupboards, onto your food-prep surfaces, into your bed, closets, other furnishings; and leaving dried urine puddles, fecal droppings and hair EVERYWHERE.
You need to clear all food storage and examine the spaces and the food for contamination immediately, and get professional help managing this plague.
It does not matter that you can't see any points of ingress or seldom see an actual mouse. They are living there because they have found a source of food. If there are enough of them for you to hear them in the damned walls, you have a serious problem, to the extent that a housefire may actually leave you better off.
posted by BigLankyBastard at 10:17 AM on March 29, 2016 [1 favorite]


I know for a fact that they chew through wires in cars because they did this to a car I had. I was very disappointed with my indoor/outdoor kitties for not preventing this, although I have only once seen a mouse in the house and it was quickly dispatched. My mechanic said mice eathing through car wiring happens all the time.
posted by mermayd at 11:15 AM on March 29, 2016


eew. Mice, ticks, Lyme disease and other tick-borne diseases.
posted by girl Mark at 11:12 AM on March 30, 2016


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