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Discussion Starter · #1 ·
Hi, In the last two days I noticed a foul burning smell in my kitchen when I was boiling water using my kettle 4 times in a row, but wasn't sure what it was. Yesterday I was using my mini oven on the counter and 10 minutes later I saw sparks coming out of my receptacle. I quickly turned off the oven and sparks stopped. I opened the receptacle cover and found out that the plastic insulation on the wires and nut were melting. See pictures.
Is that green stuff oxidation? Could this problem be caused by the constant boiling of water around that receptacle?(the other hot wire was not oxidized).
Or is it because of a loose connection? Would a GFCI prevent the sparks from happening and trip right away?

Thanks,

Thomas
 

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I vote for a loose connection if that is the spring from a wire nut shown.

A gfi is going to trip from an imbalance between hot and neutral current, not a loose connection.
 

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Discussion Starter · #5 · (Edited)
Do you have aluminum wiring by chance? I see a silver EGC?
Yes we have aluminum wiring in the house with copper pig tailing work.
As for Jim's post, if there are sparks, doesn't that mean that there was a short and thus the GFCI would trip? It wouldn't have helped in this situation?
What's with the green stuff then? It's oxidation right?
 

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Yes we have aluminum wiring in the house with copper pig tailing work.
As for Jim's post, if there are sparks, doesn't that mean that there was a short and thus the GFCI would trip? It wouldn't have helped in this situation?
What's with the green stuff then? It's oxidation right?


No gfci looks for current imbalance between line and neutral. What you have is a high resistance connection hence the heat. A short would have picked up by a fuse or circuit breaker.i don't know whom did previous work. But would hire or at least consult a electrican. The wire nuts I show. Previous are rated for al cu connections. Since your outlet is not rated for al.I encourage you to act sooner then later on correcting this.
 

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Yes we have aluminum wiring in the house with copper pig tailing work.
As for Jim's post, if there are sparks, doesn't that mean that there was a short and thus the GFCI would trip? It wouldn't have helped in this situation?
What's with the green stuff then? It's oxidation right?
Whilst a short should trip a gfci,
Not all sparks are caused by shorts,
a corroded wire/bad splice can also cause sparking,
which will not trip a gfci.
for that you need a afci.

i see oxidesed screws and wires
no doubt the true cause of the problem
is it humid enviroment ?
 

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The green is from the Copper and Aluminum in contact with each other. It causes a reaction that most think that it is Oxidation. In reality it is the two metals basically reacting to each other.

Whoever taped that mess up, did not know what they were doing.

You do need to go through and fix all of the outlets to make sure that they done correctly.

Also if you want a better piece of mind and have Circuit Breakers. You can use the AFCI breakers to make sure when this does happen again. The breaker will trip instead of letting that run away condition happen.

You are lucky that it happened while you were at home and right there. Most of these happen when people are gone or in bed asleep.
 

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Here is the Consumer Product Safety Commission findings on copper/aluminum connections.
http://www.cpsc.gov//PageFiles/118856/516.pdf

Note that the wire nuts in your photos are not an approved method for copper to aluminum connection. Even the purple wire nuts are not an approved method of permanent repair. They should be considered temporary.

In addition to repairing the failed connection, you should go thru the house checking for similar connections and replace them. Doing it DIY, the AlumiCons would be the way to go. Or hire an electrician for the COPALUM fix.

The best fix would be a re-wire to remove all of the solid aluminum wiring in your branch circuit wiring.

While adding AFCIs gives another level of protection and would be a wise addition, they do not fix the root cause of the problem.
 

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The green is from the Copper and Aluminum in contact with each other. It causes a reaction that most think that it is Oxidation. In reality it is the two metals basically reacting to each other.
The type of reaction of two metals in contact can vary, but in this case oxidation is correct.

The green is quite a a distance from the wire nuts, and confined to a couple specific pieces of plastic. The wire nut connection is also encased with tape. For those reasons I don't think your aerosolized reactants would behave like that.
 

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Discussion Starter · #15 · (Edited)
The green is from the Copper and Aluminum in contact with each other. It causes a reaction that most think that it is Oxidation. In reality it is the two metals basically reacting to each other.

Whoever taped that mess up, did not know what they were doing.

You do need to go through and fix all of the outlets to make sure that they done correctly.

Also if you want a better piece of mind and have Circuit Breakers. You can use the AFCI breakers to make sure when this does happen again. The breaker will trip instead of letting that run away condition happen.

You are lucky that it happened while you were at home and right there. Most of these happen when people are gone or in bed asleep.
Thank you for the response. As per the post below, if it is oxidation, it occurred AFTER or BEFORE the melt away? You say that someone messed up the work - what did they do wrong? It looks like they taped OK like the other nuts, no? Because if I go through other outlets I need to know what to look for.
As far as using a GFCI or AFCI or both, will I be able to because there are two fuses (2 hots - it's a black, red, white, ground) to that one receptacle? That white wire on the top is actually a hot.
When there were sparks, doesn't that mean there was a short because electricity flowed elsewhere, so why didn't the fuse trip and why wouldn't a GFCI pick up the lost power?
I need to buy some black insulated copper wire and cut off the burned part right?
 

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The red may not be a separate circuit. It could simply be a switched hot on the same circuit as the black.

The wire nuts used are wrong for the purpose. The wire colors used are also incorrect.

A short is an incorrect path to a grounded surface. You had arcing on the hot to another part of the hot.
 

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Discussion Starter · #18 ·
The red may not be a separate circuit. It could simply be a switched hot on the same circuit as the black.
It wouldn't make sense then to connect two hot leads. No I really don't think it is the same circuit as there are two 15AMP fuses in my fuse panel and I'm not sure if you can see the metal plate was removed between the two screws.
 
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