Aluminum EGC and GEC Question

[Bjenks]

When running Aluminum service or feeders I have a couple of questions about what is a better design or typically done in the field:
1) While 250.64(A) does allow Aluminum GEC in certain situations, does anyone every use Aluminum or is it best to just always use copper for the GEC?
2) While 553.8(C), 555.15(B), 680.23(B)(2), 680.25(A)(2) doesn?t allow Aluminum EGC because of corrosion and MC All Purpose uses Aluminum for the EGC, if Aluminum is specified as the current carrying feeder conductor do you typically still use copper for the EGC or keep the metals the same?

I ask this as I typically go either all Aluminum or all Copper when I do an electrical one-line (actually I might do Aluminum service and then copper feeders). However, when I go in the field I see a lot of copper EGC installed with aluminum feeders. So I wonder what is typically seen out in the field and from other designers?

 

[petersonra]

When running Aluminum service or feeders I have a couple of questions about what is a better design or typically done in the field:
1) While 250.64(A) does allow Aluminum GEC in certain situations, does anyone every use Aluminum or is it best to just always use copper for the GEC?
2) While 553.8(C), 555.15(B), 680.23(B)(2), 680.25(A)(2) doesn?t allow Aluminum EGC because of corrosion and MC All Purpose uses Aluminum for the EGC, if Aluminum is specified as the current carrying feeder conductor do you typically still use copper for the EGC or keep the metals the same?

I ask this as I typically go either all Aluminum or all Copper when I do an electrical one-line (actually I might do Aluminum service and then copper feeders). However, when I go in the field I see a lot of copper EGC installed with aluminum feeders. So I wonder what is typically seen out in the field and from other designers?

IMO it just does not matter all that much. The GEC is not all that important to begin with.

personally I would limit the use of AL to wires above a certain size like #4 or 1/0 or whatever you think is appropriate. the money saved is in the larger sizes mostly.

 

[Dennis Alwon]

When running Aluminum service or feeders I have a couple of questions about what is a better design or typically done in the field:
1) While 250.64(A) does allow Aluminum GEC in certain situations, does anyone every use Aluminum or is it best to just always use copper for the GEC?

I allows use copper however I do residential and , as mentioned above, the cost difference is not as great when it comes to the larger sizes grounding electrode conductors that may be required. There is nothing wrong with aluminum but it generally is speced as copper.

2) While 553.8(C), 555.15(B), 680.23(B)(2), 680.25(A)(2) doesn?t allow Aluminum EGC because of corrosion and MC All Purpose uses Aluminum for the EGC, if Aluminum is specified as the current carrying feeder conductor do you typically still use copper for the EGC or keep the metals the same?

I keep my metals the same however it is compliant to mix except perhaps in parallel runs of the same line.

 

[Bjenks]

IMO it just does not matter all that much. The GEC is not all that important to begin with.

personally I would limit the use of AL to wires above a certain size like #4 or 1/0 or whatever you think is appropriate. the money saved is in the larger sizes mostly.

Lets suppose you decide #1/0 or larger can be aluminum and you use a #1/0 or larger Al feeder from a service disconnect to a remote MLO panel somewhere. Would you use a copper EGC until you got up to say an 800A feeder that would require a #1/0 CU or once you go with Aluminum feeders you do the EGC Aluminum too?

 

[Dennis Alwon]

Lets suppose you decide #1/0 or larger can be aluminum and you use a #1/0 or larger Al feeder from a service disconnect to a remote MLO panel somewhere. Would you use a copper EGC until you got up to say an 800A feeder that would require a #1/0 CU or once you go with Aluminum feeders you do the EGC Aluminum too?

If you trust the feeder to be aluminum why would you worry about the equipment grounding conductor. Certainly in pool areas that is different but there is no reason to use copper equipment grounding conductor with aluminum feeders

 

[Bjenks]

If you trust the feeder to be aluminum why would you worry about the equipment grounding conductor. Certainly in pool areas that is different but there is no reason to use copper equipment grounding conductor with aluminum feeders

I think I am second guessing myself as when I go out into the field to do a retro or addition and there is aluminum feeders, I noticed that a lot of times they are running copper EGC. I will admit these aluminum feeders are typically for 800A or less that I am looking at and might be why they use copper in that case. So I was wondering if I was missing something on why this is being done.

 

[petersonra]

If you trust the feeder to be aluminum why would you worry about the equipment grounding conductor. Certainly in pool areas that is different but there is no reason to use copper equipment grounding conductor with aluminum feeders

I agree. My suggestion was to pick a size that is the minimum size you will use AL in. It could be #6 or 1/0 or whatever you decide is appropriate based on your own judgement. if the wire is smaller than that size it is always copper. If it is larger, it can be AL if appropriate. I don't have a problem with not mixing metals either if you are more comfortable with that, although I just don't see that it matters any.

Some customers may be willing to pay more for copper. let them pay more.