Article 250.20(B)(2)

[alixenos]

Hello,

I'm trying to understand the system grounding, and the following appears in the NEC

250.20(B)(2): where the system if 3 phase 4 wire wye connected in which the neutral conductor is used as a circuit conductor.

So the article says for system 50V to 1000 V AC, the system must be grounded if the above applies.

My question is: are there any system that are 50V-100V AC 3 phase, 4 wire, wye connected, in which the neutral is not used as a circuit conductor? If yes, how does that affects the grounding?

Thank you.

 

[tortuga]

Hello,

I'm trying to understand the system grounding, and the following appears in the NEC

250.20(B)(2): where the system if 3 phase 4 wire wye connected in which the neutral conductor is used as a circuit conductor.

So the article says for system 50V to 1000 V AC, the system must be grounded if the above applies.

My question is: are there any system that are 50V-100V AC 3 phase, 4 wire, wye connected, in which the neutral is not used as a circuit conductor? If yes, how does that affects the grounding?

Thank you.

Not a 4wire, a ungrounded wye would be a 3 wire 3 phase.

 

[infinity]

My question is: are there any system that are 50V-100V AC 3 phase, 4 wire, wye connected, in which the neutral is not used as a circuit conductor? If yes, how does that affects the grounding?

A 480Y/277 volt Wye system without using the neutral would not require to be grounded {250.20(B)(2)}. A 208Y/120 volt system without using a neutral would be required to be grounded. {250.20(B)(1)}.

250.20(B) Alternating-Current Systems of 50 Volts to 1000 Volts.
Alternating-current systems of 50 volts to 1000 volts that supply premises wiring and premises wiring systems shall be grounded under any of the following conditions:
(1) Where the system can be grounded so that the maximum voltage to ground on the ungrounded conductors does not exceed 150 volts
(2) Where the system is 3-phase, 4-wire, wye connected in which the neutral conductor is used as a circuit conductor
(3) Where the system is 3-phase, 4-wire, delta connected in which the midpoint of one phase winding is used as a circuit conductor