Overhead service drop conductors copper to aluminum

[clsarmiento]

I have a situation wherein a contractor wants to feed a 200A rated panelboard temporarily from an existing wireway/gutter located from a remote location . From the existing wireway, he wants to use #4/0 copper in conduit riser to a weatherhead, then use a #4/0 Quadraplex aluminum cable in free air overhead to another weatherhead and then back down with #4/0 copper in conduit riser to the panelboard. Is this installation legal, or per NEC? Thanks.

 

[iwire]

As long as the calculated load is under 180 amps (the rating of 4/0 AL) it sounds fine.

 

[infinity]

What's the ampacity of #4/0 Al in free-air?

 

[texie]

Is this 1 phase or 3 phase? If it is 3 phase with a neutral, I'm not sure how you do this as you will be short 1 conductor (you need 3 line, neutral and EGC). Don't think there is such a thing as quintuplex (4 insulated + bare msger). I've never done an overhead 3 phase feeder since the new rule for an EGC to feed a seperate building. Maybe some others can comment on this.

 

[resistance]

What's the ampacity of #4/0 Al in free-air?

Where applicable?assuming this case applies--could you use Annex B to get an answer?

 

[iwire]

What's the ampacity of #4/0 Al in free-air?

What is the temp rating of the connectors he is using?

 

[LEO2854]

What is the temp rating of the connectors he is using?

I thought you could use table Table 310.15(B)(20) for tryplex cable in free air...

 

[iwire]

I thought you could use table Table 310.15(B)(20) for tryplex cable in free air...

You are correct, I was mistaken.

I thought that table had higher temp columns.

 

[resistance]

I thought you could use table Table 310.15(B)(20) for tryplex cable in free air...

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