Need advice - Outlet caught fire

The Xbox is not very high draw at all. esp. when compared to a space heater or hair dryer. See AnandTech - Welcome to Valhalla: Inside the New 250GB Xbox 360 Slim. I have the power pig 1st gen Xbox 360 (aka Xenon).

I'd be most concerned about the space heater as those can be pretty high draw and might be on for a long time. The one in my room pulls almost 800 watts on the lower setting and a bit over 1100 watts on high.

I don't run my hair dryer for very long.

If you don't have one already, I recommend a P3 - Kill A Watt (or one of their fancier models) to figure out what's high draw. It also can help you identify vampires and where you can save electricity. It's one of the best cheap gadgets I've bought in a long time.

 

This is a very common problem with wiring of that era.

Homeowners should be able to find plenty of information about it. Here are a few starters:
Wikipedia: Aluminum wire
NYT: The Fire Dangers of Aluminum Wiring
This Old House: 7. ALUMINUM WIRING

 

///////////--Glad to hear that things are getting better. Question: What do you mean by pigtail? Do you mean a splice? Splicing any wire is alright in a low current situation. But with high draw, heaters, stoves,irons, toasters, coffee pots etc, A SPLICE can not be counted on! At that point, of splice the wire will heat up again. And important to remember: That wiring, which your electrician inferred was deficient, is still all over your house! As Kitty pointed out, a kilowatt meter is the cheapest and best buy out there. I have always had multimeters and find the kilowatt meter extremely useful for AC. You might want to further analyse the rest of your outlets. When I was stationed in Japan, I opened one of the outlets to check it,I was flabbergasted. The insulation was all totally dry, falling off in small pieces that were all very brittle, this is generally what happens to old wiring and insulation. I did not accept the air pockets explanation. Can the screw or spring mechanism loosen because of 40 years of corrosion, more likely, during humid weather, the hot wire is slightly shorting out and pulling more current. Cleaning and tightening the connections would cure the problem, but replacement of all outlets and switches is better.

See above

 

The industry has made special parts that can deal with the problems of aluminum wires and aluminum-to-copper connections. Please start with the links I posted above.

OP's description is a reasonable 2nd-hand retelling of a very well known problem of aluminum wiring commonly installed in the 1960s-1970s. Thermal expansion and contraction leaves small gaps between contacts, which then oxidize and produce a poor connection, which then heat up more and expand and contract more, which then ...

The brittle, cracked, falling off insulation you experienced in Japan is a separate issue, which OP's electrician did not mention is this case. The examples I have personally encountered were on older wiring than OP has, and on 'temporary' extension cords permanently stapled into place.

 

did they really use aluminum wiring in 1972? i thought it was a result of copper shortages during wwII. nevermind, i just read your wiki. thanks fuzz!

 

Thankyou Fuzzy, Some really good information at those sites.

Cheung_francis Aren't you lucky? Your PIP found a fire hazard for you!

 

Aluminum wiring.....huh! I read a long time ago about the hazards in home wiring. Forgot all about that! good call!

 

Isn't that strange, I was in the same boat, maybe I retained 10%, That's not bad,

 

The way I understand it is, the aluminum expands and contracts more with temperature change than copper does, and this is how it becomes loose. Then, loose connection = more resistance = heat. And since more resistance = less current flow (because the current is busy heating things up instead of running appliances), the breaker will NOT trip, unless you have an Arc Fault breaker.

The OP should have the electrician install a 240V outlet for the car, since it sounds like he will be there a while anyways. And I agree that fixtures designed for aluminum are a better bet than an aluminum-copper splice or pigtail connection in the electrical box.

 

Good work!

Andyprius # 1:

Question: What do you mean by pigtail? Do you mean a splice?

​

It's not a splice exactly. You take a piece of copper wire. One end screws to the switch or outlet, the other is twisted around the aluminum wire and capped with a nut. You no longer have contact between aluminum and screws. It's a standard fix and is supposed to work.​

 

You must not use ordinary wire nuts, that just shifts the problem location. Special AL-compatible parts are required to prevent corrosion and ensure a reliable connection.

 

Hey I thought this was Prius chat, not electrician chat! Lol

 

Thanks to homecharging of PiPs, PriusChat and electrician-chat now have some overlap!

 

OP, happen to have any pictures of the damage?

 

You've got a combination of factors here. GFCI or lack thereof has nothing to do with it. It is not uncommon to feed power from one receptacle to another using push-in type receptacles. These things are notorious for making poor connections, especially considering shrinkage that might occur after 40 years. If you have these push-in type receptacles in your house, I would change them...NOW.

Also, the longer the run (extension cord combined with existing house wiring), the more resistance and thus heat is generated. keep your runs as short as possible.

It's also just not a good idea to mix your bathroom and your garage or outdoor circuit. Any circuit where a device pulling more than 8-10 amps constantly is going to be used should be a dedicated circuit...not one where power is fed from one outlet to another and another and another...

 

I wouldn't be that worried about them. What fjpod is talking about is power outlets where the house wires are just pushed into holes in the back as opposed to be screwed on. Most outlets that I have seen have both. And these are the cheapest 89 cents ones at HD. Of course I don't know what was being sold 30, 40 or 50 years ago. But this wasn't the problem in this case...the problem was the use of aluminum wiring which is a well documented problem.

I'm not sure which is worse after many decades...the springs in the push in connectors staying tight...or bending the end of the wire and the screw staying tight.

Yes, longer runs have more heat generated. But it is (about) the same amount of heat per unit distance. And that's all that counts for fire danger. You aren't getting a significantly hotter connection in a pass-through GFCI outlet because you have an extra 10 or 20 feet of wire to get to your garage and then to the car. I'm sure the NEC (National Electric Code) has all the maximum runs quantified somewhere. When my house was built I found two out-of-spec wiring problems and called the city inspector. He went through everything (including additions since inspection) with a fine tooth comb. I ending up suing the builder in small claims court to pay for the fixes. We had already added a new distribution panel and had a run in the backyard of >100 ft and all were in code.

There is nothing wrong, incorrect or unsafe about having a garage and bathroom on the same circuit. It is not a "good idea" when you will be frequently charging a car and using the bathroom with a hairdryer (for example). But that is just an inconvenience. When charging the car and you turn on the (1200 - 1500 watt) hairdryer your breaker should instantly trip. You should either: a) not do this; or b) run a dedicated circuit for the car. But it is not going to start a fire unless there is another problem. My house is wired like this. But it is a our downstairs guest bathroom that is also on the same GFCI as the garage. There is no reason for me to change it. If you have 3 kids that all use such a bathroom, then maybe you want a new circuit.

Virtually every kitchen is wired with many outlet to outlet to outlet wiring. And then people plug in coffee makers and toaster ovens that run for long periods. I doubt anyone checks which outlet is closest to the source breaker.

Mike

 

wow!

 

Thanks for keeping us up to date with this, as more EVs go into old homes, we need to keep up awareness that a dedicated circuit is not just a 'nice' idea. It is vital.

 

^^^
Wow!