480/277V or 277/480V?

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If you wanna be consistant with the NEC you would use 480y/277, see 220.5

Roger
 
wannaknow said:
What is the difference in the notation? When is it better to use one and not the other?

Thanks
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The correct terminology is 480Y/277 for a 3 phase 4 wire system

There are actually several rules to follow ("/" means something special as does an "X"). But, in general, 3 phase systems list the high voltage first then the low voltage (Y is added after the high voltage if the system wye). Single phase systems are listed as the low voltage first, then the high voltage.
 
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