1030 Aluminum

[TJDNJ]

The NEC requires aluminum wire to be grade 8000. I'm designing the installation of several 400/600A 480V UG feeders, direct buried with USE quadruplex cable for a campus style installation. All of the cables will terminate in fusible outdoor panelboards. I've noticed most of the triplex and quadruplex aluminum cable offered by suppliers is grade 1030 and would like to know what the problem is with using this grade of aluminum for an all underground installation?

 

[mdshunk]

What is the insulation type on the conductors of the type USE cable? That might make a difference.

The NEC only requires the 8000 series alloy on 8, 10, and 12 gauge, along with most gauges of RHH, RHW, XHHW, THW, THHW, THWN, THHN, SEU cable, and SER cable. You "out" for using this cable might be that it is an assembly called "USE cable" and not individual conductors. The 8000 series alloy requirement doesn't seem to apply to type USE cable. See 310.14

Type 1030 aluminium is pretty darned pure. As memory serves, Alcan says you need to use a compression connector on 1030, as it will cold flow too much in a mechanical lug. Don't quote me on that, but I think that's right.