My house is very old (100+ yrs), and has been renovated at least twice.
It looks like most of the circuits in my house run on 12 gage wire. But here and there I’m finding some lights, switches and a couple outlets wired with 14 gage. Is this something I should worry about?
All the things running on the smaller wire seem to work fine. Am I bound for trouble, or is this no big deal?
My first reaction would be to say that you shouldn’t have any problems.
To be on the safe side, was the wiring redone or upgraded when the previous renovations were done? Does the service use breakers or fuses? What is the service rating (in amps)? Is there wiring in an attic and/or basement/crawl space and what condition is it in (I know of homes in your age range that have bare wires in the attic using insulators)?
Do you have fuses or breakers? As long as the right size fuse or breaker is installed the smaller wiring isn’t a problem. The problem often arises that when the fuse keeps blowing, the home owner will sometimes put a larger value fuse in. This stops the fuse from blowing, which makes them happy. Unfortunately, it also means you are overheating the wires, which can lead to fire, and hence is generally regarded as a BAD THING. It’s harder for a home owner to swap out a breaker, so they aren’t usually a problem, as long as the original guy who did the conversion from fuses to breakers sized them right.
If you have a case of a larger breaker going through larger wire then being split off onto smaller wires, this is also a BAD THING. The breaker/fuse needs to be sized for the worst case, which is one load on the thinnest wire. If you have 14 gage wire anywhere on the branch, you can’t have anything bigger than a 15 amp breaker/fuse. If you have a 20 amp breaker/fuse, you darn well better have 12 gage wire on every branch in that particular circuit.
Thanks for both replies.
The circuits for the minor appliances (*not *the oven, water heater, furnace, etc.) are on 20 amp breaker switches.
engineer_comp_geek, looks like I’ve got my night all booked up, checking every wire in the house… :smack:
You’ve got two choices, then, to live safely. Either go over every inch of wiring and ensure that it’s all 12 ga on the 20-amp circuits, or pull out the 20-amp breakers and replace them with 15-amp breakers.
My pick would be to downgrade the breakers. A: It’s quick B: It’s pretty much guaranteed to be the safe choice. C: It’s cheap. Assuming you have a normal breaker panel, the breakers are about four bucks each. (eg: GE, Sears, Murray, Square D Homeline, etc.)
In modern construction, most of the branches are 15 ampere excepting kitchen, bathroom, clothes washer which must be 20 ampere 210.11©, and household cooking appliances, clothes drying, water and household heating, and air conditioning equipment, if supplied.
FWIW, capricious breaker changing may create a problem, as many different models will physically fit, but aren’t listed or labeled by the panelboard manufacturer for installation, making their placement a violation of 110.3(B), as well as UL White Book. Before installing a breaker into a panelboard, ensure that the type of breaker is listed as appropriate on the data sheet inside the enclosure door.
I would also check the insulation. If it’s thermoplastic insulation, you’re probably okay (as long as everything else checks out). If it’s old enough to be a cloth-like material, you could have some deterioration problems. The old stuff gets brittle and crumbles. On the good side, it hasn’t been used for a very long time, so if your renovation was within the last 40 years or so, it should be fine.