National Electrical Installation Standards

Standards as High as Your Own

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Friday, July 26, 2019

Question:

Re: CQD answer published Friday, July 12, 2019 -480 V 3 wire needs 277 V-2

Sirs: As always, thank you for your valuable service. It is appreciated by many. Regarding 'converting' 3 phase 480 volt to lighting poles to 1 phase and deriving a neutral. Would it be legal and code-compliant to disconnect one phase at the breaker; re-identify it as a neutral; change the 3-pole breaker to a 2-pole single phase breaker; and obtain your neutral in that fashion?

With so many conversions of parking lot lights to LED, there is often as much as a 75% reduction in load and many of the lights are 277v instead of the old 480v. The old systems didn't need a neutral; with 277v lighting this would seem to be the easiest conversion.

Is it allowable? Thank you, Gary

A

Answer:

Hey Gary thanks for your question and the kind words. Yes, if a neutral point, as defined in Article 100, exists on the transformer supplying the circuit and the neural conductor is grounded and if the grounded conductor is 4 AWG or larger and it is identified with white or gray marking at their terminations as stated in 200.6(B)(4). That might be a cost-effective solution.

If the wiring method is a multiconductor cable and only qualified persons are allowed to service the installation then smaller conductors can be identified at their terminations with a white coloring as stated in 200.6(E).

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