A customer called the shop with a voltage problem that is burning up boards at a MRI facility.The service is feed from a 1200 amp gear that is located outside.From the gear a 400 amp breaker feeds the facility with 500 mcm to a self contained 400 amp 3phase mtr can.From the mtr can the customer did not run a ground to the 2 200amp panels instead he is using parr. 2 in. emt conduit.Inside he is also using just the conduit for a ground on all his branch circ. and he is sharing neutrals.Should this have deicated neutrals and grounds to this euipment?The load on the service is about 30 amps so its not overloaded
Sharing neutrals
- Thread starter newt
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- Lockport, IL
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- Semi-Retired Electrical Engineer
Re: Sharing neutrals
I don't quite follow the situation. What is burning up? What do you mean by "burning up boards"? Is the conduit getting hot?
I don't quite follow the situation. What is burning up? What do you mean by "burning up boards"? Is the conduit getting hot?
Re: Sharing neutrals
You're not very clear as to what sort of service this is, but it sounds like a wye-connected 3-phase 208/120v with the equipment powered by 120v. As for whether separate neutrals are required depends on manufacturer or construction specs since code doesn't prohibit it that I can see.
You're not very clear as to what sort of service this is, but it sounds like a wye-connected 3-phase 208/120v with the equipment powered by 120v. As for whether separate neutrals are required depends on manufacturer or construction specs since code doesn't prohibit it that I can see.
(2002) Section 517.13 (A) & (B) definitely requires redundant branch circuit grounding for electrical equipment located in a patient care area ("wherein patients are intended to be examined or treated"). The raceway (conduit, cable sheath, armor, etc, per 250.118) is the first grounding means required by (A), while (B) requires an insulated copper conductor to be run with the branch circuit conductors within the grounded raceway required by (A). Surprisingly, I don't see anything requiring the feeders to the panels supplying those branch circuits to also supply redundant grounds.
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