Aluminum ampacity

[blueheels2]

Doing a panel change today on a home with aluminum wiring. Receptacles and lights are #12 aluminum on 20 amp breakers. 2020 and 2017 say 15 amps in the 60 degree column but my 2008 says 20 amps in the 60 degree column. I don’t hav me a 2011 or 2014 handy. What year was the change made?

 

[augie47]

I think it's a moot point as in the '08, 240.4(D) still limits the OCP deviced to 15 amps on 12 Al.

 

[Dennis Alwon]

Why would you be reading the 2008 when NC is on the 2017 for residences.

 

[infinity]

Why would you be reading the 2008 when NC is on the 2017 for residences.

He said panel change so I'm guessing it's an existing installation.

 

[blueheels2]

Why would you be reading the 2008 when NC is on the 2017 for residences.

2017 was in my van and I was in the house. I took a look in the 2008 thinking it would be the same but noticed it said 20 amps. Something in my memory said 12 Al was only good for 15 amps so I took my lazy self out to the truck and took a look.
My interest in knowing when the change was made is so when this customer asks why I installed 15 amp breakers instead of 20 amp breakers I can tell her that the NEC no longer allows them on 20’s and the change was made in this code cycle blah blah blah. But as Augie pointed out even in the 2008 you could only put it on a 15 amp breaker.

So better question, I’m assuming when this panel was installed in the 70’s 12 Al was good for 20 amps. When was the change made that 12 Al was only good for 15 amps?

 

[Dennis Alwon]

2017 was in my van and I was in the house. I took a look in the 2008 thinking it would be the same but noticed it said 20 amps. Something in my memory said 12 Al was only good for 15 amps so I took my lazy self out to the truck and took a look.
My interest in knowing when the change was made is so when this customer asks why I installed 15 amp breakers instead of 20 amp breakers I can tell her that the NEC no longer allows them on 20’s and the change was made in this code cycle blah blah blah. But as Augie pointed out even in the 2008 you could only put it on a 15 amp breaker.

So better question, I’m assuming when this panel was installed in the 70’s 12 Al was good for 20 amps. When was the change made that 12 Al was only good for 15 amps?

The 2011 has the change so 2008 was the last year it was allowed-- well actually it was compliant until the 2011 was accepted in your area.

 

[curt swartz]

The 2011 has the change so 2008 was the last year it was allowed-- well actually it was compliant until the 2011 was accepted in your area.

Dennis, you are saying prior to 2011 #12AL was permitted for 20 amp circuits? I don't have access to any older code books right now but don't think that is correct. I have never installed small AL conductors but every installation I have seen starting from the late 60's used #12 for 15 amp circuits and #10 for 20 amp circuits.

 

[don_resqcapt19]

In the 2008 code the small conductor rule in 240.4(D) limited the OCPD for 12 AWG aluminum to 15 amps.
I am not aware of any edition of the code that permitted the OCPD for 12 AWG aluminum to be 20 amps. In the older codes the ampacity table shows the ampacity at 15 amps. Not sure when the table was changed to show 20 amps.

 

[LarryFine]

Dennis, you are saying prior to 2011 #12AL was permitted for 20 amp circuits? I don't have access to any older code books right now but don't think that is correct. I have never installed small AL conductors but every installation I have seen starting from the late 60's used #12 for 15 amp circuits and #10 for 20 amp circuits.

I agree with this.

 

[Dennis Alwon]

Here is the the 2008

 

[Dennis Alwon]

However 240.4 says this so you could use 20 amps to de-rate,

 

[augie47]

Sounds familiar for some reason

 

[Dennis Alwon]

Dennis, you are saying prior to 2011 #12AL was permitted for 20 amp circuits? I don't have access to any older code books right now but don't think that is correct. I have never installed small AL conductors but every installation I have seen starting from the late 60's used #12 for 15 amp circuits and #10 for 20 amp circuits.

I was responding to Blueheels who asked when the Table was changed. I stated that 2011 was the change from 2008. I never stated that you could use 12 al on a 20 amp circuit.

My use of the word compliant was not good as it appears to mean it is compliant at 20 amps. I meant it was compliant to use 12 al at 20 amps but that is only for de-rating purposes. I don't believe 12 al could ever be used on a 20 amp overcurrent protective device except for perhaps a/c units.

 

[blueheels2]

Interesting, definitely 12 AL on 20 amp FPE breakers on the change I did today.

 

[augie47]

If its an FPE breaker it really doesn't matter... crap-shoot if it will trip at any amperage