ECN Forum Forums Code Related Discussion NEC & other Code issues 15kv cable conduit fill

Can anyone tell me where I can find dimentsions for 15kv concentric neutral cable? Customer wants it in pipe. It looks like a 500 kcmil cable, but there must be a place in the code book with the measurements for it. any help would be appreciated. Thanks, Gary

I found it

It is not recommended to put concentric neutral cable in conduit, it is intended to be direct buried. If you wish to put it in conduit, get jacketed concentric neutral cable. Over the years, we have bad performance from concentric neutral cable in conduit.

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Charlie Eldridge, Indianapolis, Utility Power Guy

charlie, what performance problems ? We are going to put it in PVC. What do you mean by jacketed, I tought it already had a jacket on it(Black jacket with pinkish insulation inside)? It is listed for direct burial, but the customer wanted it in pipe. If we bury it without pipe, still would need a riser. Would this hurt the wire also? Always good to get advice from the other side of the fence.Thanks, Gary

We have put miles of cross-linked solid dielectric bare concentric neutral in the earth with some in PVC conduit. We have had a lot of failures with the cable in the conduit. We quit using the bare concentric neutral and went to a polyethylene jacket over the concentric neutral cable and have had no trouble with the jacketed concentric neutral cable.

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Charlie Eldridge, Indianapolis, Utility Power Guy

Charlie,
Did you ever pin point why the cable was failing? The utilities here run it in PVC all the time.

I seem to remember a problem with arcing between the concentric neutral conductors and the outside of the cable.