ECN Forum Forums General Topics of the Trade General Discussion Area Older Homes

I'll go with Ed on the stupidity, especially plugging a few too many space heaters/blow dryers/air conditioners into old 50s circuits, which already serve most of the house.

My second would be homeowner/handyman tampering, based solely on the pictures I've seen here.

Ian A.

I'd say deteriorated grounds, damaged insulation, and evidence of overloaded receptacles tops the list.

Having seen a number of "electrical" fires, i.e. the source of ignition was electricity, the causes I've seen mostly go from miss-use to DIY repairs.
Portable heaters on extension cords or too close to cumbustables.
Light bulbs against combustables.
NM cable tapped onto knob & tube, with some tape wrapped around the joint.
Panels with different brands of breakers jammed in, they almost fit.
Biggest cause of failures: Users and hack repairs.
I still remember the guy that swore he did not put a penny behind a fuse, that over loaded and caused a fire. He said, My momma told me to never use a penny behind a fuse. That's why I used a nickle.
It is easy to put 20 and 30 amp breakers in where those 15's were. Those will be the fires of the future.

I'm trying to figure out why these taps would fail. They should be no more dangerous than the original K&T, which I am given to understand is quite safe. The modern tape and solder should be even better than what they had originally.

I think Alan means just poorly made splices, like just loosely wrapping the new wire around the old and taping it up. I doubt any average person would go as far as to solder the joints etc.

OK John, time to fess up, what is most likely to burn my house down?

Ian A.

From the original post.



So the things that were on the load side of the outlet, ie: extension cords and heaters etc. were not part of the examination!

... Except the extension cords that were still in place.

I cheated too

The home owners must have packed up all their extension cords and heaters when they moved out. Anyway, this study might find that the average house's house wiring (as part of the house itself) may have few serious defects. Serious enough to fail in a way to cause a house fire. Some that almost caught fire (charred insulation, but didn't quite burst into flames, or the fact that the metal junction box kept the embers off flammable materials and saved the day), other problems that were never stressed enough to get even started on the way to a fire (code violations that would have failed seriously if they were ever asked to fail in a safe way (penny behind the fuse, but no overload or short ever happened on that circuit)).

I know someone who had an "electrical" house fire. He was cleaning his basement, and moved a space heater to a temp storage spot next to some other stuff but didn't notice that it was still plugged in. And he usually catches things like this, but somehow not this time. Later its thermostat decides it's cold, and turns the heater on, and the stuff next to it catches fire. User errors like this may explain most electrical fires.

This study would still be worth while, if nothing else than to identify the areas that really need attention (like the heater on extension cord).

I must confess to knowing the results of this examination .....Reno told me on the ECN chat.

The study confirmed a lot of electricians' beliefs - and directly challenged the assumptions behind much code growth.

First, for the "non-problems."
"Old" equipment generally performed well, when subjected to the same UL testing as was done at the time of manufacture. That is, wire insulation (even brittle rubber) and circuit breakers (even FPE and Zinsco) worked, unless they were damaged in some way. Likewise, old switches and receptacles either did just fine, or had some obvious problem with them.

The houses either had very few / no code issues .... or had plenty. As in 'more than 25.' here we are speaking of basic violations (things like over lamping and over fusing), rather than, say, not having the more recently required telephone jack.
The code problems were -no surprise to sparkies here - generally associated with poor attempts to change / modify / "improve" the original electrical system.

Probably the biggest hazard found lurking within the homes was suggested by signs wires had overheated. This was indicated by either the older rubber insulation decaying, or by scorched insulation. The most common site of this was near lighting fixtures, suggesting over-lamping for extended periods. There was also the matter of over-fusing.

Poor splicing / flying splices / and double lugging were all common features of additions to the original electrical work. Sometimes the report understates things: for example, "extension cords left in place" was a very nice way of describing a cord that came out of a receptacle, a cord that was then stapled to the baseboard, and then went in a hole in the wall - where it fed a newly installed receptacle. Such cords always had several coats of paint. (Though one more recent such was found, only it used the newer yellow romex :D)

Receptacles found generally fit into two categories: either they were the original two-prong type, or someone had replaced them with three-prong types. In several instances, the three-prong receptacles were wired in a manner that would fool a plug-in tester.

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Just for grins, let's look a my personal home. I think this will show what we have to deal with.
My place was built in 1940. No skimping here - it was wired with romex that just might have come from the very first production run. Very 'cutting edge' at the time; K&T was commonly used in this neighborhood until Kennedy was President.

The kitchen had a single receptacle - you could only plug in one item. In the only electrical change made over the years, a duplex receptacle was added for a refrigerator. Naturally, this receptacle was installed in a non-compliant manner.

Wires near the lighting fixtures (both of them!) is in good shape. The reason for this is suggested by the fact that I still have the glass covers to these fixtures; over-lamping was prevented by the lack of room in the globes.

The main room, which measures about 12 ft square, and has 28 ft. of continuous wall, has a single duplex receptacle, part of which is switched. There's another 6 ft. wall section, and there was a 4 ft. section - both without any receptacles. It's safe to assume that this room has seem many extension cords / power strips / cube taps / adapters over the years.

It's very likely that the room was once larger, with the wall that creates a bedroom being added later. This would account for the presence of three receptacles in the bedroom - none on either side of the dividing wall.

The only receptacle in the bath is the one in the base of the light over the sink. Two prong, no GFI.

The original service - in use until a few years ago - was a 60 amp fuse box. Two of the four fuse spaces were used for household wiring. A third was for the space heater in the bath. The range fuses were not used (gas range). The water heater was fed from a second meter.

One outside light; no outside receptacles.

I think we can see how my place's electrical is inadequate for even a fairly modest modern life. I know, it's hard to imagine a kitchen without both a fridge and a toaster - but that was the state of thing in 1940. Likewise, out living rooms have far more to plug in than just a radio and a lamp.