Thread: copper clad aluminum branch circuits

Just to be sure, am I correct in concluding that copper clad AL conductors also need to be upsized just the same as standard AL?

For instance, a 20amp circuit will need #10 copper clad AL?

Originally Posted by John Dirks Jr

Just to be sure, am I correct in concluding that copper clad AL conductors also need to be upsized just the same as standard AL?

For instance, a 20amp circuit will need #10 copper clad AL?

Think of copper clad aluminum as aluminum conductors (they are aluminum conductors), so, yes, they get sized the same as aluminum conductors are sized.

Copper clad aluminum conductors also only go in terminals rated for aluminum, not terminals rated only for copper.

I was pretty sure of it but just wanted confirmation. Thanks Jerry.

It's not that they are "upsized", it's that AL has a different amperage rating that CU. That's why AL conductors are typically larger than CU.

Originally Posted by Speedy Petey

That's why AL conductors are typically larger than CU.

That's why they are "upsized".

Originally Posted by Speedy Petey

It's not that they are "upsized", it's that AL has a different amperage rating that CU. That's why AL conductors are typically larger than CU.

Yup!

Just to sum it up,

14 gauge CU would mean 12 gauge AL for 15 amps

12 gauge CU would mean 10 gauge AL for 20 amps

10 gauge CU would mean 8 gauge AL for 30 amps

Above those sizes you would typically go to stranded AL. As a general rule of thumb if you see 14 gauge NM its automatically CU. If no 14 is present in the house good chance its AL or the sparky just like #12 Kitchen circuits are always 20 amp so if those are #10 they might be AL.

Originally Posted by Mbrooke

If no 14 is present in the house good chance its AL or the sparky just like #12

Or the builder, electrician, and/or owner are aware of voltage drop and have wired accordingly. That is unusual to find in regular production houses, but many of the builders and electricians doing high end large houses understand the need to address voltage drop and run #12 CU for 15 amp circuits and #10 CU for 20 amp circuits.

Kitchen circuits are always 20 amp so if those are #10 they might be AL.

Including #10 CU for kitchen circuits.

Some will say it is not necessary while other understand that it is. Some places you will never see the conductor size adjusted for voltage drop or derating , other places you will see it.

Originally Posted by Jerry Peck

Or the builder, electrician, and/or owner are aware of voltage drop and have wired accordingly. That is unusual to find in regular production houses, but many of the builders and electricians doing high end large houses understand the need to address voltage drop and run #12 CU for 15 amp circuits and #10 CU for 20 amp circuits.



Including #10 CU for kitchen circuits.

Some will say it is not necessary while other understand that it is. Some places you will never see the conductor size adjusted for voltage drop or derating , other places you will see it.

Good points. There are exceptions to rules of thumb I brought up. Of note just for the sake of it some larger houses will have sub panels on the second floor fed with 2/2/2/4 SER from the main just to address voltage drop.


You brought up a good fact, some inspectors during construction will fail long runs with to much voltage drop others wont. Truth is if poco is supplying power at 125/250 volts I would be to worried. Even if a 1000 foot run drops it down to 114 volts its still within tolerances, but if poco is giving say 115/230 certainly its a good idea to watch out for voltage drop.


NEC doesn't directly govern voltage drop but it recommend that a branch circuit doesn't dip below 3% under normal use.