RF Shielded Room

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ssilbers

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I am installing an RF shielded room which requires power line filters. Each filter is single phase and penetrates the steel shield independent of the other phases. Isn't this a violation of NEC section 300.20?
 
Is the room or the set of filters a UL-listed assembly? If so, I don't think the NEC would apply. Most/all of the power filters I've seen are L+N, and the few shielded rooms I've worked on had only a couple of isolated 120v circuits (light/fan, bench 1, bench 2). The only thing common was the EGC.
 
The service to this room is 208Y/120V 60amp. Each filter assembly consists of 2 filters. We need to filter phase A, B, C & neutral. Therefore, 2 filter assemblies with 2 filters in each assembly. Each phase and/or neutral will penetrate the steel shield individually. The total shielded room is not UL listed. I guess if you looked at the total shielded room including the filters as a single piece of equipment, the NEC would not apply. The filter assembly is a UL listed piece of equipment.
 
Any reason you can't ran all four wires thru the housings on both filters and only connect the wires to the filters as appropriate?
 
ssilbers is this a government installation?

If so there are special specs that you will be required to follow, I have posted them before and will try to see if I can find them again, right now I'm so tired I cant even remember the name of the documents to even do a search for them but they are on the Internet, I just got in from a job and for the last few weeks been working very late just about every night, but I will try to find them if this is what I think it is.
 
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