Thread: Fried Aluminum in this panel

Holy smokes, this is why we take the covers off.

This 70's townhouse was nicely reno'd, new flooring, fixtures and faucets, new counter tops and cabinets, no problem anywhere we could see, and the panel looked ok on the outside.

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yep when I reno'd my condo I figured it would be stupid to have a beautiful renovation and have this still in the wall:

Yup FPE Stab-Loc

Originally Posted by John Kogel

Holy smokes, this is why we take the covers off.

This 70's townhouse was nicely reno'd, new flooring, fixtures and faucets, new counter tops and cabinets, no problem anywhere we could see, and the panel looked ok on the outside.

What brand of panel is that? Pretty colored breakers but I don't recognize the brand. Is that a Canada thing?

Originally Posted by Jim Luttrall

What brand of panel is that? Pretty colored breakers but I don't recognize the brand. Is that a Canada thing?

It is a Westinghouse. They appear to be the original breakers.

There is a neutral that is discoloured on the left bank and it has discoloured the inside of the panel cover.
Double tap on the left bank
There is a miscoloured neutral which should be marked black.
Aluminum neutrals are not wrapped under terminals clockwise.
Nolox anti oxidant paste on aluminum branch wires.

Out here home insurers will want any home wired with aluminum inspected by the electrical authority to ensure its in good working order, installed correctly and safe before issuing insurance policy.

Aside from all the other stuff wrong with those pictures, I'm not sure I'd be using 20A breakers with aluminum wiring. That's just asking for trouble.

Originally Posted by Corn Walker

Aside from all the other stuff wrong with those pictures, I'm not sure I'd be using 20A breakers with aluminum wiring. That's just asking for trouble.

If the wire is rated for 20 amps, why would you not use 20 amp breakers?
What would the difference be if you used a 15 amp breaker?

Originally Posted by Dan Harris

If the wire is rated for 20 amps, why would you not use 20 amp breakers?
What would the difference be if you used a 15 amp breaker?

12ga aluminum wire is only rated for 15A. A 20A breaker will allow excess current through the circuit, causing impermissible overheating.

The circuit with the scorched wire supplies baseboard heaters, so the white wire is not a neutral in this case. I believe white wires on breakers was permitted in '75, because it is typical for 240 v circuits. I suppose the electrician should correct this too.

From the scorch mark, I wonder if the bus bar may be burnt as well. It looks like smoke came out from between the breakers.

The double taps appear to be #14 Cu added to #12 Al. They are double wrong.

As of 1990, we are allowed to use #14 copper with a 20 Amp breaker for fixed load electric heat circuits. I do not know if that means what appears to be #12 Al could be used with a 20 amp breaker in 1975, but that will be a challenge for the electrician when he goes to fix this.

Originally Posted by Corn Walker

Aside from all the other stuff wrong with those pictures, I'm not sure I'd be using 20A breakers with aluminum wiring. That's just asking for trouble.

Originally Posted by Dan Harris

If the wire is rated for 20 amps, why would you not use 20 amp breakers?
What would the difference be if you used a 15 amp breaker?

Originally Posted by Corn Walker

12ga aluminum wire is only rated for 15A. A 20A breaker will allow excess current through the circuit, causing impermissible overheating.

That's why, with aluminum wiring, you would use a #10 AWG on a 20 amp breaker.

So, back to Dan's question: "If the wire is rated for 20 amps, why would you not use 20 amp breakers?"

Remember, with aluminum, you would be (SHOULD be) thinking #12 for 15 amps and #10 for 20 amps - which would be no different than #14 and #12 respectively for copper. Are you saying you would not want to use a 20 amp breaker on #12 copper? Why?

Originally Posted by Jerry Peck

That's why, with aluminum wiring, you would use a #10 AWG on a 20 amp breaker.

So, back to Dan's question: "If the wire is rated for 20 amps, why would you not use 20 amp breakers?"

Remember, with aluminum, you would be (SHOULD be) thinking #12 for 15 amps and #10 for 20 amps - which would be no different than #14 and #12 respectively for copper. Are you saying you would not want to use a 20 amp breaker on #12 copper? Why?

A 20A breaker is fine for #12 copper, unless installation conditions warrant the derating of the current capacity of the wire.

A 20A breaker is not fine for #12 aluminum and in those pictures the aluminum conductors look to be #12, not #10.

So Dan's question is somewhat oblique to the situation at hand. Certainly if the conductors are rated for 20A you can use a 20A breaker, but from what I can see it looks like the aluminum conductors on the 20A breakers are actually #12, not #10.

Originally Posted by Corn Walker

A 20A breaker is not fine for #12 aluminum

Don't be so sure. Under the 1990 Canadian code rule 62-114(8) where I live, it may be allowed. Those are baseboard heater circuits, BTW. A fixed load of 3600 Watts, in other words, 15 amps X 240 V is permitted on #14 copper, and we are allowed to use a 20 A breaker with that 14 ga. wire because the load is fixed at 15 amps.

I don't know if the rule transfers over to #12 Al. It should all be replaced IMO, but an electrician will have to design a repair here, and that's why they make the big bucks.

Originally Posted by John Kogel

Don't be so sure. Under the 1990 Canadian code rule 62-114(8) where I live, it may be allowed. Those are baseboard heater circuits, BTW. A fixed load of 3600 Watts, in other words, 15 amps X 240 V is permitted on #14 copper, and we are allowed to use a 20 A breaker with that 14 ga. wire because the load is fixed at 15 amps.

I don't know if the rule transfers over to #12 Al. It should all be replaced IMO, but an electrician will have to design a repair here, and that's why they make the big bucks.

I didn't notice you were in Canada, I'm not familiar with the canadian electrical code.

In fact, most of my electrical knowledge is from electrical engineering, not the brief stint I did as an electrician's apprentice.

And according to my calculations #12AL has approximately 77.65% carrying capacity as does #12CU. Which translates to 15.53A for #12AL when #12CU is rated for 20A.

The other problem with aluminum wiring is oxidation, which increases resistance and leads to intermittent connectivity when not properly terminated. So even if #12AL is allowed for a heater circuit with a 20A breaker, unless I was assured it was properly run and terminated I would be suspect of it.

Considering the scorch marks this tells me that line is drawing more than what it is rated for and something is amiss.

Originally Posted by Raymond Wand

Considering the scorch marks this tells me that line is drawing more than what it is rated for and something is amiss.

Yeah but..... are you sure it's not simply a loose connection that caused this?
There's a bit of black around the screw head. The other leg does not look burnt.

Loose connections are the main reason for scorching in the panel. I know this cuz I read it here.

Originally Posted by Corn Walker

And according to my calculations #12AL has approximately 77.65% carrying capacity as does #12CU. Which translates to 15.53A for #12AL.

Ok. The rule allows the wire to be loaded to 100% of its capacity in a heater circuit. Then they allow it to be protected by a breaker one size larger, in this case, a 20A. In fact it has to be, or the breaker would be tripping constantly.

So even if #12AL is allowed for a heater circuit with a 20A breaker, unless I was assured it was properly run and terminated I would be suspect of it.

Right you are. I would have been calling for checking of heaters, receptacles and fixtures anyway, the burn makes it a no-brainer - this needs fixing..

Originally Posted by Dan Harris

If the wire is rated for 20 amps, why would you not use 20 amp breakers?

Originally Posted by Corn Walker

So Dan's question is somewhat oblique to the situation at hand.

No, what YOU applied to Dan's question made YOU think there was something wrong with Dan's question - but Dan's QUESTION was very clear.

Originally Posted by Jerry Peck

No, what YOU applied to Dan's question made YOU think there was something wrong with Dan's question - but Dan's QUESTION was very clear.

Whatever Jerry. Happy Halloween.

Just my own observation.
The AL wire on the 20A breakers looks like #10 to me.
Look at the bottom two twins on the left side. The cu looks like #12TW while the al looks like #10TW.
They are definitely NOT the same size.

Same goes for the black and burned white above them.