# 12 AL wire on 20 amp breaker

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Sierrasparky

Sierrasparky

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Electrician ,contractor
HI,
Was #12 AL ever allowed on a 20 amp OCD in a residence or Hotel?

I just found a whole hotel wired this way!
 
I looked in the 1959 NEC and there were some AL conductors listed with an asbestos insulation that had an amperage rating up to 30 amps for a #12 AL however the temperature rating would greatly exceed the terminals on the devices. The max amperage of a #12 AL is 15 per table 310-14 1959 NEC. There was a conductor listed with a RHH insulation that was 25 amps but a note stated that 15 amps was max.
 
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jwjrw said:
I guess you would have to research 310.5 to see when it first appeared?
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Why, is it all underground? :D

SEO said:
I looked in the 1959 NEC and there were some AL conductors listed with an asbestos insulation that had an amperage rating up to 30 amps for a #12 AL however the temperature rating would greatly exceed the terminals on the devices. The max amperage of a #12 AL is 15 per table 310-14 1959 NEC. There was a conductor listed with a RHH insulation that was 25 amps but a note stated that 15 amps was max.
Click to expand...

1956 was the first year aluminum conductors got their own table. Prior to that, they were allowed to be 84% of the ampacity of the same-size copper conductor.
 
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480sparky said:
1956 was the first year aluminum conductors got their own table. Prior to that, they were allowed to be 84% of the ampacity of the same-size copper conductor.
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480sparky I knew that you would have some older information. My NEC library isn't nearly as complete as yours, I wish it was.
 
I would think 12 aluminum would be allowed on 20 amp circuit in the same instances where 14 copper is allowed on 20 amp circuit, like motors and air conditioners, but not lighting and receptacle outlets.
 
480sparky said:
Why, is it all underground? :D



1956 was the first year aluminum conductors got their own table. Prior to that, they were allowed to be 84% of the ampacity of the same-size copper conductor.
Click to expand...

Underground? Does 310.5 have anything to do with underground? :confused:
 
jwjrw said:
Underground? Does 310.5 have anything to do with underground? :confused:
Click to expand...

I'm thinking 300.5
smiley-signs140.gif
 
Most of the AL installs that I've seen (NM cable) took place in the 60's. The kitchens were wired with 12-2 cu. Could you imagine connecting receptacles to a 10-2 al.
 
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