how to Ground with 3 wires vs 4 wires system

[powerelectronic]

Hi All

here is the situation:
///3 wires
transformer feeds electrical panel, having power system of 3 phases, 3 wires, neutral to ground at delt-star transformer.

-do i need run the neutral wire from transformer to the equipment although 3 wires only system is used at the equipmet level.
-if neutral wire is omitted, what if there is ground fault triggered at the point of equipment?

////4 wires
what if power system is 3 ph, 4 wire, can i omit the ground wire, or use transformer neutral as ground at equipment?

what NEC section relates to the applicaiton?
i am puzzled, any thought will help :arrow:

 

[eric stromberg]

////4 wires
what if power system is 3 ph, 4 wire, can i omit the ground wire, or use transformer neutral as ground at equipment?

what NEC section relates to the applicaiton?
i am puzzled, any thought will help Arrow

I'm assuming this is a separately derived system. If this is the case, the code section is 250.30.

1 - If the equipment does not have a neutral, as in a MCC unit, then you do not need to run the neutral to the equipment.
2 - The system bonding jumper can either be at the transformer or at the first disconnect.

Eric Stromberg, P.E.