A question about single conductor cable

[chris_r]

What would be wrong with this:

Lets say you need a triple run of 200A to get a 600A 3 phase circuit.
You want to use single conductor ACWU but nobody in Canada stocks it in this size.

The reason we can use this stuff is to get the free air rating and use smaller cable and save money. You need to space them apart to minimize mutual heating due to inductance etc etc.

For a 3 ph 3 Wire circuit If you were to use three runs of 3 conductor ACWU, with all conductors in each cable the same polarity, wouldn't you in effect have a cable on each phase that could be treated like it was a single conductor cable and be given a free air rating?

[jeeper]

If I understand it you would want to use a 3 multi conductor cable like a single conductor with the same phase on all three cables of the multi conductor cable.
No you can not. CEC rule 4-004(1)(a) states that only single conductor cables may use the free air capacties Table 1. 4-004(1)(b) states that a 3 conductor cable shall use Table 2.
So this is the way I see it. But have the job engineered with a stamp and you maybe allowed to do it. More research would be needed and a possible contact with the cable manufacturer.
Just in case you happen to read 4-004 (8), the Table 5B derating applies to a triplex or quadplex type cable.

[twh]

12-106(1) prohibits that.

[jeeper]

Short comment, to the point, nice call.