MRI disconnect

[hhsting]

I have tenant fit out where they are using MRI. They are brining isolated equipment grounding conductor to the MRI disconnect. The isolated equipment grounding conductor in the MRI disconnect has grounding electrode to building steel.

I am wondering would the grounding electrode at MRI disconnect be in compliance with NEC 2017? Anyone know and installed MRI here

 

[roger]

You need the original manufacturers engineered drawings. The MRI equipment and associated wiring is outside of the NEC. In most cases the whole room including control booth is listed as an assembly.

 

[infinity]

Why is there a GEC for an MRI?

 

[hhsting]

Why is there a GEC for an MRI?

The disconnect for the MRI is where the scope
Of contractor stops and MRI manufacturer starts. There is GEC at the MRI disconnect and drawing says per NEC 250. Do you know of which exactly where in NEC 2017 Article 205?

 

[jaggedben]

The disconnect for the MRI is where the scope
Of contractor stops and MRI manufacturer starts. There is GEC at the MRI disconnect and drawing says per NEC 250. Do you know of which exactly where in NEC 2017 Article 205?

Sounds like an Auxiliary Electrode as allowed (not required) by 250.54. Only the manufacturer documentation could say if this is really 'required'. It seems to me there is a conflict between having an auxiliary electrode and an isolated EGC, but I'll let those who are more familiar with isolated EGCs speak to that.

It's sort of nonsensical for a drawing to say 'per NEC 250' (that's not specific enough), but especially for an auxiliary electrode because 250.54 really doesn't say anything about how to install an auxiliary electrode, except that it be connected to an EGC. 250.54 only says which other parts of 250 are not required to be followed.