How to recognize faulty wiring in apartment?
July 20, 2011 7:51 PM   Subscribe

How do I recognize poor wiring in a home?

In my history of renting, I've encountered three apartments where the house had old wiring and could not handle the demand of the electronics in use. In one apartment running a microwave and the dishwasher along with an air conditioner would result in the living room lights being shut off. I would have to resort to flipping the switches in the breaker panel then turning the AC off while the dishwasher ran.

Currently, I am in a duplex apartment where the top floor was without electricity for two weeks because the microwave, 32-inch flatscreen TV, and dishwasher all ran simultaneously. We had to wait for the landlord to find an electrician cheap enough to fix the burnt wire. Thankfully, the refrigerator was operational after running an extension cord to a working outlet. The house was built in 1914.

I know that even if a house is old, it does not mean the wiring is shoddy. For future apartment rentals, I would like to acquire some knowledge on what to look for in terms of stable wiring. I am not an electrician, but I want to take comfort in knowing I won't have to run to the breaker panel every time two ACs, my desktop computer, laundry, the microwave and an HD TV are running.
posted by ayc200 to Technology (15 answers total) 6 users marked this as a favorite
A simple solution would be to not run everything at once. If the washing machine is on, turn off the AC or the flat screen. If the microwave is on, turn off the washer. You can look at your breaker box/fuse panel to figure out how much juice you can run at the same time.
posted by woodjockey at 8:00 PM on July 20, 2011

Bring an outlet tester with you when you tour an apartment.
posted by Admiral Haddock at 8:00 PM on July 20, 2011

This is not a sure fire method, but a decent start would be the circuit breaker box. With what you are discussing, you would want to be looking for as many 20A circuits as you can get. That is not going to confirm that the electrician distributed those circuits in a wise way, but it would be a reasonable jumping off point.

I don't think most residential circuits sneak much over 20A. The hope would be them doing it room by room or something else logical (like keeping laundry on its own circuit).
posted by milqman at 8:02 PM on July 20, 2011

In one apartment running a microwave and the dishwasher along with an air conditioner would result in the living room lights being shut off.

Actually, this is probably the correct behavior. All three of these are large electrical loads, and putting them all on the same circuit is going to force the breaker to flip regardless of the age of the wiring. Circuit breakers trip in order to protect the downstream wiring and devices from damage. If you've got a single circuit that's rated for 15A and you try to pull 20A of load through it, you're going to damage the wiring[1], so your breaker will correctly trip.

The thing to look at isn't the age or anything, but how many individual circuits you have in your apartment.

Er.. On preview, what milqman said.

[1] It's not going to melt the copper, and it's not going to damage it all at once, but over the years, it'll damage the insulation. The big danger of overload (rather than a short circuit) is heat -- wires are rated by how much current they can carry without generating too much heat, and if you have wiring too hot for too long the insulation around the wires can end up turning to dust.
posted by rmd1023 at 8:09 PM on July 20, 2011

Yeah, look in the breaker box. See how big the breaker on the input side is, how much power the whole home can draw. Then see how many circuits (more is better) and how big they are. If you find aluminum wiring or old fuses, you can expect troubles.

The other thing to check is whether there's a proper third wire for ground. A tester can tell you that quickly.
posted by Nelson at 8:10 PM on July 20, 2011

You can map the circuits. Each circuit in a residential house is good for 15 amps if the wiring is done right, 20 amps if people are cheaping out and assuming you'll put too much load on a single circuit. Watts is, to a rule of thumb, volts times amps, which is why household appliances peak out at 1800 watts: 1800 watts = 120 volts * 15 amps.

So you get one toaster oven, refrigerator, window air conditioner, or other high draw appliance per circuit. You get eighteen hundred watt bulbs per circuit.

In newer houses you generally have a bunch of circuits on 15 amp circuit breakers. In older houses you can have as few as 3 circuits on 20 amp fuses (this was how my 1947 cottage was wired when I moved in, first thing we did was replace the 60 amp drop to a fuse box with a 200 amp circuit breaker box, and add a few extra circuits).

Lights are supposed to have their own circuit (or one or more), so that when you blow a fuse or trip a circuit breaker, you aren't stuck in the dark.

So, when you move into a place, map the circuits: Plug lights in to the sockets, go to the breaker box, flip breakers off, map which breakers go to which socket. Once you know where the sockets go, don't plug more than 1800 watts worth of appliance (and appliances generally have how many watts they'll draw peak written on them) per circuit.

Can't help you in the case where the breakers or fuses don't blow and you melt the wiring, but if you exceed 1800 watts on a circuit, the breakers and fuses are there to make sure you're not melting the wiring.

(We could go deeper, like measuring the voltage at the socket under load to see if you've got bad connections, but if you're asking this question you don't want to be anywhere near a live circuit with voltmeter probes, so we'll skip that for now...)
posted by straw at 8:14 PM on July 20, 2011 [2 favorites]

If you know which breakers go with which circuits/switches/outlets in the house, one way to get a useful sample of wiring quality is to turn off the breaker for a lightswitch, remove the switch plate, and look at how things are hooked up in the little metal box in the wall. Different switches require different wiring schema, but there are still things that can serve as "red flags".

We actually just ran into this very issue at my workplace (my employers rent a suite in a mid-sized office building) -- lightswitch went screwy, and when I took off the plate, I stood there going o_0 for quite a while. There was electrical tape wrapped (haphazardly) around everything, and whoever had attempted to wire up the switch (I am thinking previous tenants, NOT a real electrician, unless they were drunk) had used thick stranded wire (as opposed to solid wire), and had just smooshed it under the screw terminals on the switch. This had caused the strandy bits to splay out, poke through the electrical tape, and obviously short to something nearby (as part of the electrical tape was melted). Needless to say, professional electricians were called in, and they said we probably had grounds to complain to the landlord.

OK, that was a bit of a tangent, any case, my point is that if there's anywhere you can SEE any of the wiring, it's worth looking for any connections that look weak, any wire that looks burnt/discolored/decayed, any discrete wires twisted and taped rather than connected properly with wire nuts, etc. You don't need to do anything invasive to do this...things like switch plates come off easily with screws. One bad circuit doesn't mean everything in the house is bad, of course, but one bad circuit probably does mean you want to call in a real electrician (or encourage your landlord to do so). And I cannot emphasize enough that you MUST know what outlets/switches go with what breakers before doing anything remotely resembling what I am describing in this paragraph.
posted by aecorwin at 8:36 PM on July 20, 2011

Look at how many circuits you are getting.

With only a few exceptions (washer/dryer, air conditioner, dishwasher, etc.) 15 amps is plenty of juice for most of your needs. It will run your hair dryer or your microwave or your TV. It probably can't handle your hair dryer AND your microwave AND your TV.

There are a couple different philosophy out there - I like the one where a rooms outlets are on one (or two) circuit(s), ceiling lights are ganged on different circuits and the kitchen has a bunch of different circuits for all the different things you might pull a lot of juice with there.
posted by Kid Charlemagne at 9:04 PM on July 20, 2011

In a typical breaker box you'll find there's one large main breaker at the top that can shut off the whole residence, and a number of smaller-value breakers for the various branch circuits. The number on the main breaker tells you how much power is available to the whole apartment, and the numbers on the other breakers tell you how much power is available to each branch circuit.

You want to see a reasonable value on the main breaker. 40 or 6o Amps is common in some older apartments, but is pushing your luck for a modern house with a lot of high-draw appliances. 100A is enough for a small house. 200A is generous for even most larger houses.

You want to see a bunch of branch circuits. The value of breakers used for lighting and basic 110V outlets will be 15 or 20 Amps* If there are only a few breakers, then too many loads will be drawing power from the same circuit and you'll trip breakers frequently. Having many branch circuits will mean that the loads can be spread out over them, so no one branch circuit has to be pushed to its limits.

When you look at electrical outlets in various rooms, you want to see 3-prong outlets. The old 2-prong outlets indicate that the wiring in the walls is quite old, no matter how new and shiny the breaker panel might look.

The burnt wire problem you encountered in your current apartment is harder for an amateur to forsee. This will never happen if the residence is properly wired. It happened to you because some wiring was done improperly. This would be difficult to detect while inspecting a prospective apartment (pulls out screwdriver and says, "You don't mind if I take this apart, do you?").

*Straw: Each circuit in a residential house is good for 15 amps if the wiring is done right, 20 amps if people are cheaping out and assuming you'll put too much load on a single circuit.

I agree w/everything else Straw wrote, but the above snippet is wrong. 20A circuits do not indicate that anyone has cheaped out. 20A circuits require heavier, more expensive outlets, switches and wire.
posted by jon1270 at 4:02 AM on July 21, 2011

So jon1270 is right on the "20A circuits require heavier, more expensive outlets, switches and wire", when done right. Many building inspectors will disallow 20A outlets in residential construction, even in garages (where they could be useful). I'm not in the trades, just a homeowner who tries to do most of my own work speaking from homeowner and renter experience, but I've seen more 15A sockets and 14 gauge wire on 20A fuses than I have 20A sockets and 12 gauge wire on 20A breakers.

And one other note on his comments: I believe that 200A to a single family house is currently code for new construction, although there's no reason you couldn't run a 200A capable feeder to the main drop, and then put 100A breakers in. But that's getting way away from your original question.
posted by straw at 7:23 AM on July 21, 2011

aecorwin writes "There was electrical tape wrapped (haphazardly) around everything, and whoever had attempted to wire up the switch [...] had used thick stranded wire (as opposed to solid wire), and had just smooshed it under the screw terminals on the switch."

There is nothing wrong with stranded wire per se. It is common in commercial installations where wire is pulled through conduit because stranded wire pulls easier.

straw writes "Many building inspectors will disallow 20A outlets in residential construction, even in garages (where they could be useful)."

This is weird. I don't know specific rules like this in the states but in Canada 20A plugs are one of only two legal options for kitchen counter plugs. And a very popular option because the other option, a three wire Edison circuit, requires a ridiculously expensive breaker for plugs anywhere near sinks.
posted by Mitheral at 9:07 AM on July 21, 2011

So just to be clear, and I'm getting out beyond the limits of my knowledge of code: By a 20A socket, I mean one where one of the prongs has the option of being perpendicular to the other, not just two parallel prongs plus the ground.

Which I know only because I have a high end dust collector that has a 20A plug, with a 15A adapter for when you have to plug it into a smaller circuit and you're supposed to be careful about what you then plug into the dust collector...
posted by straw at 9:53 AM on July 21, 2011

Straw - if you're in the US, I think you're misinformed about requirements of the electrical code. (If you're not in the US, you're outside of the scope of my electrical knowledge).
posted by rmd1023 at 11:26 AM on July 21, 2011

rmd1023, you could be correct, as I said, I'm just a homeowner, so the stuff I remember is mostly "this seems like good practice when I rework this part of the house" rather than "this is legal". Passing inspection isn't nearly as interesting to me as being safe and never having to fix something in the house twice.

Digging a little deeper (grabbing my handy copy of Code Check Electrical 6th Edition p.16-18), it looks like you can put 15A sockets on a 20A circuit, and, in fact, the kitchen requires two 20A accessory circuits. In my area the new construction I'm familiar with has 15A sockets in the kitchen. So I withdraw my statement about 20A circuits, but stand by my opinion that more 15A circuits (on 12ga rather than 14ga wire) with 15A sockets is a better idea than fewer 20A circuits with 15A sockets.

And my observation that building inspectors sometimes won't allow 5-20R* sockets (the aforementioned socket allowing plugs with perpendicular pins) in residential construction comes from anecdotal conversation amongst woodworkers talking about the travails of wiring their shops legally.

The observation about 200A drops to new construction is what I was told when we had the 60A fuse box in our house replaced, but that may have also been PG&E policy, or California or our town's amendment to code.

So, yeah, don't take anything I've told you as gospel, but do map your circuits and don't put anything more than 15A or 1800 watts on a circuit unless you know what you're doing.
posted by straw at 12:02 PM on July 21, 2011

(Oh, I'd also add that I once lived in a rental with a 50A(!) breaker on the circuit to the living room. We let some teenagers house-sit once, they had a LAN party and, yes, melted a socket.)
posted by straw at 12:03 PM on July 21, 2011

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