CU to AL

[mstrlucky74]

I am in bit of a pickle and looking for advice. Been asked to do a quick/rough cost saving on a bunch of CU feeder to go to AL. I guess the quickest and easiest way would be to convert all the sizes I have in CU to Al for the same ampacity …conduit would be minimal impact. Thanks.

 

[drktmplr12]

I am in bit of a pickle and looking for advice. Been asked to do a quick/rough cost saving on a bunch of CU feeder to go to AL. I guess the quickest and easiest way would be to convert all the sizes I have in CU to Al for the same ampacity …conduit would be minimal impact. Thanks.

You will need to check with your local supply house to figure the difference in cost of CU vs Al. They should be able to supply you with a price list for both.

Be sure if you upsize the gauge and go to aluminum that you don't violate conduit fill. Often times you will need larger conduit for the same circuits. Is the raceway underground or exposed? It costs less to upsize PVC than it does RMC.

Not all equipment can accept aluminum wire so you have to be mindful of what you are terminating to. This isn't a problem for panelboards, switchboards, transformers since their terminations are usually rated for both. One problem is if you are on the upper threshold of a frame size (circuit breaker) the aluminum conductor might not fit in the lug. The terminations also will need an antioxidant applied in accordance with the mfr's instructions.

Aluminum has higher resistance than copper. Voltage drop will need to be considered, if longer distances are at play, which could make the gauge even larger.

Some designers will specify all feeders over a certain amperage (say 250 A) be aluminum in an effort to save money on the big feeders.

 

[petersonra]

One problem is if you are on the upper threshold of a frame size (circuit breaker) the aluminum conductor might not fit in the lug. The terminations also will need an antioxidant applied in accordance with the mfr's instructions.

have you ever seen a lug instruction sheet that actual says you have to use antiox compound?

BTW, most times you can replace the lugs if they are not big enough although most times they are sized large enough to take the larger aluminium wires.

 

[drktmplr12]

most times they are sized large enough to take the larger aluminium wires.

You're right. Only pointing out that OP should be mindful of what size lugs.

 

[petersonra]

You're right. Only pointing out that OP should be mindful of what size lugs.

It's the same problem if you want to use a single conductor versus parallel conductors. Sometimes the lugs don't match up to what conductors you want to use and you need to change the lugs.

 

[JFletcher]

I'm not sure what the question is here... You need to know your calculated load, and then just price out aluminum conductors with that. if you are over 800 amps, you have to go with the breaker size. Aluminum is substantially cheaper than copper, unless it requires adding to, upsizing or replacing existing conduits.

Without knowing any details about your installation, how much savings is impossible to figure.