Need advice - Outlet caught fire

I would bet on the bathroom wiring being on the same circuit as the garage

 

Ask a licensed Electrician. In fact have one make an analysis and recommend a solution. Make sure your homeowners is paid on time. Make sure the smoke alarms work.

 

I am not an electrician. Specifically I am not YOUR electrican. This is not electrical advice.

I think the owners manual specifically discourages you from using an extension cord, but I suspect the 40 year old GFCI recepticle in your bathroom was never designed to charge cars. (For any potential PIP owners in an older house, have your electrican examine your planned charging circuit BEFORE use)

Pass & Seymour 2095W TradeMaster 20 Amp 125-Volt AC GFCI Duplex Receptacle, White - Amazon.com

 

The GFCI recepticle in the bathroom was not connected to the extension cord. But I am curious, what was the awg rating of the extension cord. 12 awg is recommended

 

sounds like bad wiring or a GCFI that is never going to trip?? not common. usually they work in reverse and trip too easily.

my bet is bad wiring. 40 YO wiring is not very old. code was updated way before that. older installs used aluminum wiring that was too thin but that was in older (very older) mobile homes usually.

 

wouldn't it have to be a ground fault, not excess current?

 

with all those fire works? sounds like the wire got too hot inside the GCFI and instead of tripping like it should, it melted the plastic enclosure first.

 

It's possible that it was - it's quite common to use a GFCI receptacle to protect other outlets downstream. The National Electrical Code requires all outlets in outdoor or wet locations to be GFCI protected; the two ways of doing this are to use a GFCI breaker to protect the entire circuit, or a GFCI outlet to protect itself and the rest of the circuit downstream.

The second method requires that the GFCI outlet has to carry the full downstream current, which for charging the PiP was evidently too much.

I'm also not an electrician, but I am an EE and have worked on house wiring for a friend in New Jersey with full building department inspections.

 

b/c it wasn't a fault to ground but excess current. so it wouldn't trip, fuses, or circuit breakers blow when current exceeds the rating of the circuit breaker or fuse, GCFI's trip when there's a connection from the hot lead to the sink which conducts electricity when wet to the pipes in the sink

I have an Associate Degree in Bio-Medical Electronics

 

If the house is correctly wired, all the garage outlets are protected by a GFCI, it is common practice to use the one in a bathroom. (where GFCI is also required)

So the same breaker is used, and the first outlet in the circuit uses a GFCI recepticle, so when it detect a ground fault, all the plugs turn off.

Electrical Wiring in the Home: gfci for multiple outlets, digital voltmeter, line terminals

(there is a nice picture on that page, but I can't import it, sorry)

 

I agree

 

Since we are discussing our expertice, I am a network consultant, I never play with more than 12 volts.

 

Hair dryers pull a lot of electricity. The wires running to the 120 in the bathroom are probably pretty worn. I have a 1950s house. Just had new circuits run. The car plug is on its own circuit.

 

Hi Kitty, I am not sure on how to use this forum so forgive me if I id it wrong. YES<YES<YES The DATE has been changed. Thanks to all for the help. An extension cord of 12/3 is a must. This rated for 15 amps. However being on the same line as the bathroom is not good. A hair dryer or any other electric devise, shaver etc, could put you close to or over the 15amps. Result trip breaker ( good) or (BAD) HEAT. Lots of heat = fire. Find another line or don't use the bathroom.

 

i would replace the breaker/fuse as it should have tripped/blown unless someone used 14g wire ona a 20a circuit.

 

So do tell us the Outcome Cheung-Francis.

 

Run a dedicated 10g copper wire cable to a new outlet for charging your car. That will be the safest solution.

Mike

Mobile on my SGH-i717

 

Sorry, but this comment makes no sense. You could also say that 40 year old wiring was never designed to run a computer either. An amp is an amp. It makes no difference to the wiring where that amp is going. The Prius will draw about 11-12 amps while charging. Most house wiring is setup with 15 amp outlets, but the entire circuit of many outlets could be on a 15 amp breaker or 20 amp breaker (most common now) -- you need to look at your distribution panel. It is also a good idea to temporarily turn off the breaker for the circuit that you charge your car from and see what other outlets and devices are on the same circuit.

If you are using anything that (~continuously) draws another 3 - 8 amps (depending on the breaker capacity)while you are charging your car you will likely trip a breaker. 3 - 8 amps is 360 - 960 watts. The fact that a GFCI caught fire means that one or more failures occurred that should have instead safely cut off power. The first suspect is just that the GFCI was old (?) and couldn't handle the 11-12 amps (or more) flowing through it. The second suspect is the breaker that maybe should have tripped if the load was more than the max 15 - 20 amps.

As others have noted, the GFCI trips on an instantaneous mismatch of current flows through ground. The distribution breaker is heat/time sensitive. For example, a spike of 50 amps will cause it to trip quickly, while 21 amps on a 20 amp breaker may take a minute or two. These devices are analog...maybe it really trips at 22...but could be old and it will allow 24 amps for a few minutes. In any case, the house wiring has a lot of margin built-in so that at the edge of the specs you should not have a fire. Remember that the line could have been drawing 12 amps for an hour before this happened.

Mike
(mechanical & software engineer, but also formerly electrical officer on submarines)

 

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