MRI and CT considered Xray?

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jamism

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Hi everyone. I'm working on a medical facility where I have a MRI, CT, PET/CT, Mobile, PET/CT and X-ray machined. Are the MRI, CT, etc. considered as "X-Ray" equipment per NEC. All of these machines will be powered from one panel and I want to able to size my distribution per 517.73(2).

Thanks
 
This may not be quite as helpful as you would like, but my wife is an x-ray tech. I can tell you that everything you listed EXCEPT MRI uses the same kind of radiation, the same people run them for the most part, and they have to wear the same PPE (lead aprons and stuff). The MRI is different because it is just a big electro-magnet.

I don't know what the NEC has to say about it. :confused:
 
The MRI is definately not an Xray, and it can draw its maximum power for long periods of time.

The CT is a type of xray machine. The vendor installation drawings usually list a "Maximum instantaneous Power", and a "long term power".

I normally apply the Xray demand factors to the "maximum instantaneous power", and compare that to the "long term power". Then I use the larger of the two.

For example, a typical CT might have 112 KVA momentary rating, and a 20 KVA long term rating. If this was the 3rd CT to be installed, it gets a 10% demand factor. So that's 11.2 KVA demand. The 20 KVA long term rating is larger, so I would use that.
 
Not my area of expertise by any means, but my understanding is that X-ray machines have a separate article because they use extremely high power levels for very short durations, not because they are used to look into people's bodies.

-Jon
 
winnie said:
Not my area of expertise by any means, but my understanding is that X-ray machines have a separate article because they use extremely high power levels for very short durations, not because they are used to look into people's bodies.

-Jon
Click to expand...

Actually, the separate article (Article 660) is for non-medical xrays. Industrial xray machines that inspect welds, for example.

Medical xrays and CT's are covered in part V of 517.

But otherwise you are correct - they have separate demand factors because they draw current for very short periods of time.
 
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