Diagnostic Equipment Definition

[jeremy.zinkofsky]

I am designing the electrical distribution system for a proton therapy clinic and may have ran into a little grey area. Brief background, Proton therapy equipment fires a concentrated photon beam directly towards a tumor. It treats cancer like chemo, there is no medical imaging done in this process.

The question is: Does this machine classify as diagnostic equipment per NEC 517.73? I have not been able to find an NEC definition for diagnostic equipment and am weary of using the same demand factors as x-ray equipment for this installation. Any thoughts?

 

[david]

Why wouldn't the manufacturer of this equipment have a data sheet / cut sheet for the equipment.

You would think the manufacture would have wiring specifications for load,voltage drop, over current protection and min conductor ampacity

 

[jeremy.zinkofsky]

Why wouldn't the manufacturer of this equipment have a data sheet / cut sheet for the equipment.

You would think the manufacture would have wiring specifications for load,voltage drop, over current protection and min conductor ampacity

They provide maximum voltage drop, impedance, etc. at each point of connection. They also provide the momentary, long time load in kVA at each connection. They do not dictate how to size the distribution equipment up to their point of attachment, that would be my job. They only care about what voltage, power, etc. lies at their connection point.

Example: 1 such electrical connection point draws a 500kVA momentary load. I am faced with the decision to either size an XFMR to 500kVA or to take the demand factors in NEC 517.73 to size the XFMR. Obviously, if I can use NEC 517.73 it would drastically reduce the size of my equipment.

All i am really concerned with at this point is whether I can use NEC 517.73 for this application or not.

 

[steve66]

The manufacturer should have a project manager that can help answer this. They should be able to tell you what a typical install consists of.

I would be very careful about using the 517.73 demand factors. Its not your typical imaging equipment.

But then again, 500KVA is a lot, and the fact that they give you both a long term and an instantaneous rating probably means you don't have to size the xformer for the full momentary rating.