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#99137 - 07/22/06 07:11 PM X-ray machine  
Dnkldorf  Offline
Member
Joined: Dec 2004
Posts: 1,064
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 07:49 PM Re: X-ray machine  
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
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


#99139 - 07/22/06 08:37 PM Re: X-ray machine  
Dnkldorf  Offline
Member
Joined: Dec 2004
Posts: 1,064
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...


#99140 - 07/22/06 09:02 PM Re: X-ray machine  
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
Winchester, NH, US
Quote
I don't know much about the operation of X-ray machines or what freqs they use...
nor I. [Linked Image]

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. [Linked Image]

Good Luck,

LarryC


#99141 - 07/22/06 10:23 PM Re: X-ray machine  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,069
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

#99142 - 07/23/06 11:33 AM Re: X-ray machine  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,810
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

#99143 - 07/23/06 12:14 PM Re: X-ray machine  
Dnkldorf  Offline
Member
Joined: Dec 2004
Posts: 1,064
nowhere usa
Thx guys.... [Linked Image]



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