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Discussion Starter #1
I have a customer that wants to reuse some 4-wire bus duct and install it on and existing 3 wire feeder without the neutral. None of their equipment that will feed from the bus duct requires the neutral but it just doesn't seem right to me to hook it up without the neutral. System voltage is 480/277V, 3 phase, 4 wire but all connected equipment is 480V 3 phase without the neutral.
Does installing the bus duct without the neutral violate any code?
 

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But, based on parsing your OP, the client IS installing 4 conductor bus duct.

You seem to imply either this run will be feed by a 3-conductor tap -- using THWN-2 or some such.

Alternately, you seem to imply that the client already has 3-conductor bus duct installed and heated up -- and wants to extend that run with 4-conductor bus duct.

Which is it ?
 

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Discussion Starter #4
The feeder is a 3"conduit with 3-500mcm cu and a #2 insulated ground. The feeder is run from a 400 amp 3 Phase 4 wire bus plug about 200' away.
 

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I have a customer that wants to reuse some 4-wire bus duct and install it on and existing 3 wire feeder without the neutral. None of their equipment that will feed from the bus duct requires the neutral but it just doesn't seem right to me to hook it up without the neutral. System voltage is 480/277V, 3 phase, 4 wire but all connected equipment is 480V 3 phase without the neutral.

Does installing the bus duct without the neutral violate any code?


I've ran more 4 wire busway on a delta feed than I can remember. There is no issue. We also buy 480/277 rated NF panelboards and feed them straight delta from our busways , again, no issue. If you're determined to be concerned about it put some signage up at the busway termination box and the gear feeding it and maybe every 10' along the length of the run if you're feeling ambitious. The only issue I see is its's wasteful but if it's recycled then who cares
 

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Seen this type install many times. Some labelled and most not.
 

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Work on these like this a few times, we always labeled them but never an issue.
 
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