Is there a way to test if mice are chewing the wiring in your home?

[Beamin]

I am renting at an old apartment building probably built around 1900 so it seems to have been retro fitted for electricity several times. I can hear mice in the walls and often I notice the lights flicker, at first I thought this was due to window AC units coming on as these old buildings seem to have that problem, its one of those old row homes with four bed rooms, and a modern looking breaker panel in the basement but I suspect there are not enough circuits or the legs are not balanced out.

What I am worried about though is mainly fire in the walls. The lights still flicker even though I dont think any AC's or big loads are running and one time I saw the lights dim for 5-10 seconds which really worried me as thats what wiring will due as it heats up but is just enough not to pop the breaker.

I don't know  a whole lot about AC or home wiring have only installed it once. How would you tell if there are potential chewed/arcing/shorting wires without opening the walls up? Unfortunately the mice are in between units; so its a gray zone as to who is responsible us or the neighbor, I'm not sure if these buildings have brick between each address or if its just a wall. Wouldn't arcing appear as quick dimming to several lights while a sustained short would be a set of lights (hall bed room, bathroom) all "browning out" for a few seconds? I sleep with a fire extinguisher next to my bed because once I had to run into a burning building to get people out and I prefer not to do that again.

[DavidAlfa]

That's what the ground fault circuit breaker does (when any of the phases touches the ground).
Also in America you have have arc-fault detectors, supossed to detect when there's a loose connection, damaged wire, etc, causing arcing.
These aren't common in Europe, if used at all. We take 240V like real men

[xrunner]

How would you tell if there are potential chewed/arcing/shorting wires without opening the walls up?

You really can't. But you ( or the building super) can set traps and start the process of ridding the problem. But whatever damage they did is a done deal. Mice 1 humans zero at this point.

[Nusa]

You don't need much of a hole to put an inspection camera in, but that assumes you have such a camera and access to the area. I suspect you have neither, outside of your own rooms. You also need to know what you're looking at and what constitutes a problem. If you're serious about the 1900 part, there could still be knob-and-tube wiring in active use (which actually would be pretty safe even without insulation if it was properly installed and not disturbed by humans, but that's another subject).

[BrokenYugo]

Does this panel only supply your unit, or the whole building?

Either way, practically speaking your options are move or upgrade your renter's insurance. Old buildings like that always have sketchy electrical.

[Monkeh]

You would use an insulation resistance meter. Quite simple, just try not to blow anything up in the process.

While you're at it, you measure the resistance of the conductors to verify they're intact and there are no bad joints.

[Whales]

You would use an insulation resistance meter. Quite simple, just try not to blow anything up in the process.

While you're at it, you measure the resistance of the conductors to verify they're intact and there are no bad joints.

Many electricians will have devices that can be used to measure wire impedances and possibly insulation state.  They plug them into powerpoints, no invasive surgery necessary.  Might be useful, might not be, but will cost you.

[amyk]

Would damage also show up on a TDR?

[perieanuo]

That's what the ground fault circuit breaker does (when any of the phases touches the ground).
Also in America you have have arc-fault detectors, supossed to detect when there's a loose connection, damaged wire, etc, causing arcing.
These aren't common in Europe, if used at all. We take 240V like real men

they are imposed by law for years (decades now), i can quote you countries like romania also (the 300mA for cable protection, 30mA for in-house, some recommendations for 10 mA in bathrooms, 300mA in some industrial sensitive areas for the personnel like slaughter house cutting tables...), also the 'big' economies like france, deutchland denmark etcaetera, i'm talking about the countries i am aware of those electrical installs at home and industrial. in france my old apart from '80 had 30mA differential disjunctor, sad to disappoint you

[Haenk]

That's what the ground fault circuit breaker does (when any of the phases touches the ground).
Also in America you have have arc-fault detectors, supossed to detect when there's a loose connection, damaged wire, etc, causing arcing.
These aren't common in Europe, if used at all. We take 240V like real men

they are imposed by law for years (decades now), i can quote you countries like romania also (the 300mA for cable protection, 30mA for in-house, some recommendations for 10 mA in bathrooms, 300mA in some industrial sensitive areas for the personnel like slaughter house cutting tables...), also the 'big' economies like france, deutchland denmark etcaetera, i'm talking about the countries i am aware of those electrical installs at home and industrial. in france my old apart from '80 had 30mA differential disjunctor, sad to disappoint you

Germany: Ground fault circuit breaker are required for rooms having a shower or bathtub or outside outlets for all installations made after 2009. Arc fault detectors are very uncommon, as the quality level of electrical installations is in general very good. (Minus very old houses, but those are mostly renovated by now, and even they usually had a good installation...)

[DavidAlfa]

I was referring to the arc detectors.
Earth fault breakers are a standard, specially on wet areas (kitchen and bathrooms)

[jpanhalt]

I have an early 1950's second home in Cleveland area.   It has knob and tube wiring, which as mentioned would generally be safe for the long runs even without insulation.  That is, until it gets to an outlet.  Does your house/apartment include an attic or basement?  Is there evidence of rodents there?

Flickering lights in the Cleveland home have been due to:
1) Loose connections in the electrical panels (there are 4 panels from various updates and additions);
2) A loose phase wire at the utility pole; and
3) Low amperage capacity, e.g., the dining room lights flicker when the 110V washing machine runs, but not the 220V dryer.
Notably absent, no rodent problems.

As for mice, are you sure they are not rats?  In large Eastern cities with row houses (e.g., Baltimore, NYC, and Boston), rats can be a problem and are very hard to trap.  I am familiar with row houses in Baltimore, and they all were separated by brick walls, even ones near the harbor and dating back to the Clipper Ships.  See: http://www.tonerarch.com/blog/2013/6/13/your-house-and-your-facade-a-separation-agreement.html

As for responsibility for wiring, that is the apartment owner.  You would also need the owner's permission in theory to make any holes in the walls.  The walls are probably originally lath and plaster.  Even old newspapers and horse hair was used as early coats.  It is easy to repair small holes in them.  They may have a drywall covering as well.

  I don't know who is responsible for rodent control.  In theory, if you were to call an exterminator, that would be the owner's responsibility to pay, as non-payment could result in a lien on the property.  In practice, renters are pretty much responsible.  Many row houses are individually owned.  In that case, it is best just to talk with the neighbors.

[Berni]

Flickering lights would suggest the opposite danger, a poor connection.

If there is a short that pulls so much current that the lights dim then there would be many kilowatts of power flowing into that short. You would most likely hear and smell that and if it happens inside a wood wall it would already be on fire.

However a poor connection can be even more dangerous. The terminals joining the wires inside junction boxes can develop a poor connection. Once large loads are applied this causes a significant voltage drop that makes them get very very hot. This can deteriorate insulation or make the connection even looser. Eventually once a large load comes back on the connection might finally break and draw an arc that melts the terminal and wire, raining down molten metal on other things and catching it on fire.  This is especially likely to happen with old aluminium wire.

I actually had a similar flickering issue for a bit but then an entire phase went dead. Turns out a bad connection has developed up on a utility pole outside until it finally arced and opened itself. Turns out the whole pole was pretty wobbly since the wood in the ground has rotted away, the motion likely having additionally stressed the connections.

[xrunner]

All this talk of problems inside walls reminds me of the time I called the gas company. I had several mis-reads of my meter because the plastic meter dial cover was so old that it was hard to read the dials. A technician came out and said he would have to go back and find a new plastic cover for the dials on my old meter. He came back later and said that there weren't any more old covers left. BUT - he offered to replaced the whole meter for no charge. I said well fine. Then came the kicker. He said after my old meter was removed and before the new one was installed, he'd have to do a pressure test. If the pipes could not hold pressure properly he could then NOT put in the new meter OR replace the old meter, and I'd have to get the problem fixed out of my pocket. The leak could be anywhere at all.

I said, uh thanks but no thanks - by-by. 

So regarding the electric problems inside walls, yea determine if there are, but after that, who's going to tear into it all, find all the bad wiring, and who's paying for it? 

[SilverSolder]

If you are really worried about bad / overloaded wiring, maybe inspecting every electrical junction box with a thermal camera could be a good idea?  -  I once found a bad circuit breaker in my fuse box that way, it was noticeably hotter than the others...

[Gazza2]

I went through a massive mouse plague in rural Australia last season, trapping around 100 mice per night in my ceiling. When they finally all died off in winter I went and inspected the wiring and they haven't touched it. I dont know if there is something in the plastic to deter them, but they had no interest in it. They absolutely loved shredding insulation foams, and also chewed on gyprock and timber, though they weren't able to damage those materials much. Just dont let pest control poison them, its an absolute nightmare having dead mouse stink in your house for a couple of weeks when one dies inside a wall.

[Just_another_Dave]

That's what the ground fault circuit breaker does (when any of the phases touches the ground).
Also in America you have have arc-fault detectors, supossed to detect when there's a loose connection, damaged wire, etc, causing arcing.
These aren't common in Europe, if used at all. We take 240V like real men

they are imposed by law for years (decades now), i can quote you countries like romania also (the 300mA for cable protection, 30mA for in-house, some recommendations for 10 mA in bathrooms, 300mA in some industrial sensitive areas for the personnel like slaughter house cutting tables...), also the 'big' economies like france, deutchland denmark etcaetera, i'm talking about the countries i am aware of those electrical installs at home and industrial. in france my old apart from '80 had 30mA differential disjunctor, sad to disappoint you

In Spain differential disjuntors are also mandatory in all electrical connections inside a house (probably as a consequence of EU regulations). Just really old buildings don’t have them. However, arc fault detectors are optional and therefore uncommon in residential buildings, but they are considering making them also mandatory

[Kleinstein]

It is relatively rare that mice eat on the insulation. Rats may be a bit more hungry. I had a chewed cable (phone) at a place where a tube is crossing a wall and the mice my just needed more space to come through.

Earth fault protection and arc fault protection can catch most failures.

In the  US the transformers are smaller (due to the lower voltage and thus less practical cable length) and it could be a neighbor using electric hot water or a similar large consumer that may make the votlage drop for a few houses.

[rsjsouza]

Before you yake any action agains the mice, try to find the opening gap where they are coming - otherwise it will be a frustrating job trying to put them out only to see more inhabitants a few weeks later.

I had mice running inside the ceilings of my old house. In my case they were running between the ground and the first floor, thus pretty much inaccessible (stupid US houses with hollow walls and ceilings).

[james_s]

In an apartment building flickering lights could easily be from loads starting up in other apartments in the building. An occasional blip where the lights dim is normal but if they are truly flickering suggesting an arc that is a serious fault. I have see terminals burn up numerous times, at least one melted the entire plastic junction box and left a trail of smoke up the wall, dangerously close to a true electrical fire. Mice chewing on wires could result in a circuit going open or dangerous conditions but loose or oxidized connections and overloaded circuits is where fires usually start.

[james_s]

In the  US the transformers are smaller (due to the lower voltage and thus less practical cable length) and it could be a neighbor using electric hot water or a similar large consumer that may make the votlage drop for a few houses.

From what I've seen, the voltage is typically more stable in the US than in some other parts of the world where I know people, at least in areas like I live in where the grid is relatively modern. The transformers are smaller and tend to feed fewer houses which are located closer to the transformers and are usually wired in a star configuration which avoids the problem of houses near the end of the line fed by a larger source impedance. The voltage is not lower, it's 240V just like most of the rest of the world. The difference is our distribution transformers have a grounded center tap so each side is 120V to ground, the main breaker is double pole feeding two interleaved bus bars in the panel. A typical 200A residential panel will support 400A of 120V loads, though typically most of the large loads are 240V.

[floobydust]

Mice are eating soy-based insulation on wiring in automobiles. It's a consequence of the green movement away from petroleum-based plastics.
A few people have sued the car makers because they have no or poor protection to stop mice from getting in the cabin, where they can do severe damage.
I don't know that house wiring insulation is anything but PVC, which I have seen they will nibble on a little bit if starving. Try set up traps with peanut butter and lure them with bait.
You might instead have bats, they like high attic spaces and make so much noise at night.

If you are using expanding foam insulation to fill up holes in a building, an old trick we used at work is adding steel-wool. It stops mice from chewing through. They don't like chewing steel.

[tkamiya]

If you are RENTING a place, my suggest is you do nothing but report the problem to the landlord. 

If rodent chewed insulation MEGGER will show it as dust and moisture would collect and cause leakage.  I've seen lose wire-nuts and improperly installed fixture so many times.

If you do anything and something bad happens now or in future, you may be held responsible.  You definitely don't want that.

[Berni]

If you are using expanding foam insulation to fill up holes in a building, an old trick we used at work is adding steel-wool. It stops mice from chewing through. They don't like chewing steel.

Nice and easy trick there. I can imagine the sharp steel making it a rather unpleasant chewing experience. Luckily we don't have mice issues here so far, tho brick houses tend to be more mice resistant since nothing is hollow.

[floobydust]

That trick is from substations out in the middle of nowhere. Mice can do damage and sealing up holes in the tin building, it became the norm to use foam and steel wool.