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#99137 - 07/22/06 04:11 PM X-ray machine
Dnkldorf Offline
Member
Registered: 12/12/04
Posts: 1091
Loc: nowhere usa
Circuit board X-ray machine calls for specs of a 30A 208V single phase circuit.

Also calls out an additional #2 AWG insulated copper stranded, from the frame of the machine to the panel for high freq. ground.

330.3(B) says all equipment grounding conductors and bonding conductors shall be installed in the same raceway. However the machine comes with a prewired 30A twistlock plug.(standard nema plug) The #2 ground is additional to the normal #10 eq. ground.

I ran the #2 external to the emt, (tywrapped to it) from the frame of the machine back to the panel.

Did I make a boo-boo?

How do you handle this?

Thx..
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#99138 - 07/22/06 04:49 PM Re: X-ray machine
LarryC Offline
Member
Registered: 07/05/04
Posts: 782
Loc: Winchester, NH, US
Do the instructions say from the frame of the machine to the panel for high freq. ground? If the panel is some distance away, I think the #2 will be useless for RF grounding.

What do some of the amateur radio operators think?

LarryC
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#99139 - 07/22/06 05:37 PM Re: X-ray machine
Dnkldorf Offline
Member
Registered: 12/12/04
Posts: 1091
Loc: nowhere usa
Yes Larry, that is what is called out from the manufacturer..

I don't know much about the operation of X-ray machines or what freqs they use...
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#99140 - 07/22/06 06:02 PM Re: X-ray machine
LarryC Offline
Member
Registered: 07/05/04
Posts: 782
Loc: Winchester, NH, US
Quote:
I don't know much about the operation of X-ray machines or what freqs they use...
nor I.

I'm have just a little experience with the wonderful world of RF. Once upon a time, I was part of an engineering group that wrote the installation instructions for a product we sold, and in hindsight, I did not have a clue!!! We did things that, while not dangerous, did not do what we wanted them to do. So I take the manufacturer's instructions with a grain of salt.

I understand that you have to follow the instructions that came with the equipment. I'm saying as one who has been on the writing end of those instructions, what they want and what they wrote, are not necessarily the same.

Good Luck,

LarryC
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#99141 - 07/22/06 07:23 PM Re: X-ray machine
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9066
Loc: Estero,Fl,usa
When IBM engineers came up with some strange idea like that they were careful to call it a "drain" line and be sure it wasn't reidentified to green. They never used the "G" or "B" words so we would not get involved with article 250. I carried a spool of #16 and #4, to be used somewhat interchangably, only based on which gang of engineers were calling for it. I never really saw a difference between the performance of 16 or 4 but the "drain" itself was important.
I suspect they are keeping you off the EGC to prevent breaking something else. In a computer room the computer itself is the source of most of the "noise" we are trying to protect against and we are protecting other stuff.
_________________________
Greg Fretwell
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#99142 - 07/23/06 08:33 AM Re: X-ray machine
HotLine1 Online   content


Member
Registered: 04/03/02
Posts: 6833
Loc: Brick, NJ USA
DNK:
IMHO, follow mfg specs and instructions. They "RULE". Keep a copy at site for AHJ's reference, and your life should be easy.

John
_________________________
John
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#99143 - 07/23/06 09:14 AM Re: X-ray machine
Dnkldorf Offline
Member
Registered: 12/12/04
Posts: 1091
Loc: nowhere usa
Thx guys....
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