overheated junction box and how I fixed it

[cjradgowski]

Ten years ago I installed a dishwasher on what I thought was a well thought out circuit to the fuse box. I was wrong and almost burned my house down. It turns out that a plug in my garage where my wife irons is on the same circuit. So my advice is map all the recepticles in your house so you know precisely what is on the same circuit. I rewired the kitchen with 3 circuits replacing any wire that was suspect. Then to fix the toasted ceiling plaster I determined how much of the drywall paper was burned cut out a 12" x16" rectangle. Then I anchored the old ceiling using drywall screws with 1 inch nylon washers. I then cut and added a new piece of drywall to the ceiling joists and used Plaster of Paris which is very hard and does not shrink to build up the hole to within an 1/8" of finished (my walls are 1 inch thick) I am waiting for the plaster to cure so I can use joint compound to feather in the last of the repair and mount a new fixture Thank God the electrician used a metal box and followed code as far as clamping the wires so the toasting was contained in the box. Because the resistance element in the iron and dishwasher cycled on and off the wires at the junction above the light got toasted with out ever tripping the breaker.
When you view the slide show pull the page down slightly to see the titles of the pictures. The one inch drilled hole is an example I forgot to take a picture while I was doing it.

overheated junction/ fixture slide show of cooked ceiling almost a fire (http://pg.photos.yahoo.com/ph/woodpics@sbcglobal.net/slideshow2?.dir=/5192&.src=ph&.beg=0&.spd=1)

[mdshunk]

I see the pictures. Is the dishwasher/iron in the garage a different problem. Forgive me, but there's positively no way that adding a dishwasher to a circuit where ironing is done can almost burn down the house. Unless there's a bad connection or overfusing being done to the circuit, you can't burn down the house by adding a dishwasher to any circuit. Maybe there's more going on at your house than you realize?

In your fixture pictures, I really don't see anything I'd call burnt. I do see some overheated things in the junction box and some heated insulation in the fixture. Forgive me again, but you're being a little dramatic about this. Electricians see this exact thing on a quite regular basis. I can say with some degree of confidence that the fixture was overlamped for many years combined with a possible loose connection in the box. This is the root cause of your problem in the pictures.

[cjradgowski]

It scared me when I opened it up and saw all the exposed wire, every bit of tape was melted or burned off. The insulation on the wires would crumble when touched. I assumed the iron 800 watts plus the dishwasher 1700watts pushed the circuit to the limit. If you think it was the bulbs you will be glad to know the new fixture will be 6 inches away from the ceiling for better air circulation with 60 watt. I now have 2 junction boxes in the attic not connected to the fixture at all. Sorry if I got carried away.
Do you really see this a lot all the tape gone?

[Homer]

As MD says, make sure that you don't overlamp a fixture and make good solid connections.

If the circuit was properly fused for the wire size and the connections were solid then overheating should not happen. If you do happen to plug in more than 15A of load in a 15A circuit you should just experience breaker tripping or fuse blowing.

Check that you have a properly sized fuse/breaker in the panel.

Circuit Breakers used for residential applications must conform to UL489 specifications. Those breakers must be able to;

1) Carry a current of 200% of rated for no more than 2 minutes.

and

2) Carry a current of 135% of rated for no more than 1 hour.

So a 15A breaker may be able to handle 30A for up to 2 minutes and 20.25A for up to an hour.

The wire is designed to operate under the above conditions safely.

BTW, you don't have an old Federal Pacific Electric breaker panel, do you? Those breakers are notorious for not tripping when overloaded.

Homer

[mdshunk]

BTW, you don't have an old Federal Pacific Electric breaker panel, do you? Those breakers are notorious for not tripping when overloaded.

Homer

I hadn't considered the FPE possibility. It will be interesting to see how this hashes out. I can also see the possibility of this circuit having a 30 amp fuse installed in it where it should have been a 15. Seems like he did say "fuse box", but lots of people call their breaker box a fuse box even though it doesn't have fuses.

[cjradgowski]

Fuses are gone the entire house is 12-2 with 20 amp GE circuit breakers. I figured dishwasher 1700 watts 120watts for one fixture 60 for another 400 for coffee maker = 2280 / 120 = 19 amps. I know you are only supposed to go to 20amps X 80% = 16amps but the coffe maker is only on for 20 minutes in the morning and ussually not with the dish washer so I put it there. The main thing I did not realise was I needed to include the garage outlet which I did not know about. 800 to 1200 for the iron that takes me to a possibility of 29 amps short term. All these devices cycle on and off so I figure they just kept the wires hot but did not trip the breaker. Add the heat of the enclosed light fixture and you get my slow burn with no fire. I am still glad the box was steel. There were char marks if you look closely at the wood it was attached to. just pause at picture 4. Reading these forums got me to map my house and when I found out the garage plug was on the same circuit I figured I better check the fixture. One last comment this did not happen overnight it took 10 years.

[Mr T]

Did you replace that breaker?

I'd be strapping firecrackers to it in your back yard, or taking a sledgehammer to it, if I were you. I agree with the others, wires dont just become heating elements for no reason, and not trip the breaker....that is, in a properly designed circuit.

[cjradgowski]

Did you replace that breaker?

I'd be strapping firecrackers to it in your back yard, or taking a sledgehammer to it, if I were you. I agree with the others, wires dont just become heating elements for no reason, and not trip the breaker....that is, in a properly designed circuit.

I split the circuits in half feeding the kitchen. I did not think to replace the breaker. I will do that just to be safe. Thanks for the suggestion.

I also will be putting in 20 amp GFI's to upgrade my kitchen to code. I did have a question on the GFI's from what I have read I can use them with 2 wire since GFI measures potential between hot and nuetral. But what about the ground hole that is connected to nothing? Should I snake in a ground to the water pipe to the new GFI?

[dremmel]

I'm glad to see you're handling things and it's working out for you. I'm a little confused as to what you mean by "ground hole". If you're using 12/2 with ground, the ground wire should be connected to the green ground screw on the receptacle, which connects to the neutral/ground bar back at the panel if this is a straight run or home run.

[cjradgowski]

The receptacle has the wide slot (nuetral) the smaller slot (hot) and the round ground thing(hole?) with the green screw in the back. From my Main power box there are only 2 wires 12-2 no ground. So should I run a wire from the ground green screw in the receptacle to the water pipe 2 feet away or not? I am not clear on why some people adamantly oppose grounding anywhere accept at the main box. I would never use a water pipe for a nuetral but do not see the objection for a ground. But I will not do it if it is against code. If I have to fish all new 12-2 with ground it is a mote point. I was trying to avoid a bunch more plaster work since a number of the runs are sideways through the studs after the first drop. The 2 circuits right now are reusing the wire in the side walls from 2 junction boxes in the attic.

[dremmel]

Oh, I apologize. I misunderstood what you were referring to. I didn't realize you were talking about the front of the receptacle. I thought you meant the sides where the terminals are. I can't give you an answer on this one friend. But someone surely will. If it were me, I'd run new cable. I just don't like to see jerry riggin, no insult intended. Wait for others to give you their feedback. I'm sure the code addresses this.

[dremmel]

I found this reference in Wiring Simplified. "The NEC calls it the "equipment grounding conductor." It is bonded to components of the installatioin that normally do not carry current but do carry current in case of damage to or defect in the wiring system or the appliances connected to it. These components include the equipment grounding bus in the service equipment cabinet (which holds the main fused service switch or the circuit breaker panelboard, whichever is installed), frames of motors, frames of appliances such as electic range and clothes washer, the outlet boxes in which switches or receptacles are installed, and the metal conduit or the armor of armored cable." Not what you're looking for maybe, but food for thought.

[suemarkp]

If you don't have a green or bare grounding wire in your circuit, then don't attach anything to the green screw on the GFCI (that's what goes to the "ground hole"). The GFCI doesn't need a ground in order to function. Hopefully, your GFCI will come with some stickers that say "No Equipment Ground". Place these on that GFCI and any downstream receptacle that it protects (verify with the GFCI Test button to make sure power goes away from what you think is a protected outlet). Also place "GFCI protected" on all the downstream GFCI protected outlets.

If you don't have the ground wire, the code says to either install a GFCI, run a new ground all the way back to the service ground, or run a new cable. The fear with grounding to a pipe is that more and more metal pipe is getting replaced by PCV. It would be a huge hazard to ground to a section of pipe that turns out to be electrically isolated (either now or in the future).

[cjradgowski]

If you don't have a green or bare grounding wire in your circuit, then don't attach anything to the green screw on the GFCI (that's what goes to the "ground hole"). The GFCI doesn't need a ground in order to function. Hopefully, your GFCI will come with some stickers that say "No Equipment Ground". Place these on that GFCI and any downstream receptacle that it protects (verify with the GFCI Test button to make sure power goes away from what you think is a protected outlet). Also place "GFCI protected" on all the downstream GFCI protected outlets.

If you don't have the ground wire, the code says to either install a GFCI, run a new ground all the way back to the service ground, or run a new cable. The fear with grounding to a pipe is that more and more metal pipe is getting replaced by PCV. It would be a huge hazard to ground to a section of pipe that turns out to be electrically isolated (either now or in the future).

Thanks for a clear explanation The chance of a future electric isolation makes perfect sense. I will wire it the way you suggested and use the stickers on the 2 other receptacles that will follow the GFCI.
Chuck