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Posted By: leland High voltage? - 01/25/08 04:22 AM
Hi All,I know we have some HV and utility guys here so I thought I would ask.
I was doing a PM today on some equipment (unrelated), when I took a look at a G&W 4 POSITION SWITCH. 2300v.
I noticed the cables in the 4" conduit. They are terminated and bonds are all made up and bonded to the G&W cabinet. Fine.
My question is: should the the conduits be bonded to the cab aswell? Now the cables just come out of the pipe with no fittings.I thought it strange/odd there was no bond to the conduits.

Thanx, Lee

(I can post pics)
Posted By: Trumpy Re: High voltage? - 01/25/08 08:54 AM
Hi Lee,
There might need to be some testing done before the work was completed.
Likes of a Hi-Pot test or what-ever.
The reason the terminations are made like that before all the mechanical stuff is finished is pure economics, maybe the test technician could only be at that site at that time.
Sure, we would all like to have things finished, I've tested work in sub-stations here where the engineering part has not been completed, but is safe.
Commissioning HV gear is in itself a long slow process.
Posted By: Yoopersup Re: High voltage? - 01/26/08 12:23 AM
If HV cable Shields bonded both ends cable must be derated
310.60 (C) 1
Conduits must be bonded as usual
Posted By: leland Re: High voltage? - 01/26/08 03:48 AM
AAAARGGG. I'm so stupid!!!!!
I'll try to post a pic of my question.

Thanks folks, It must be hard to determine what "morons" like me ask.

Posted By: JCooper Re: High voltage? - 01/26/08 04:40 AM
I think what leland is trying to say is the hv cables come in and are terminated as usual, but the conduit they are in has no connector on it and is not bonded to the cabinet.

Did I get that right?
Posted By: leland Re: High voltage? - 01/26/08 01:46 PM
Posted By: RODALCO Re: High voltage? - 01/26/08 08:02 PM
The conduit you mean is the screen of the cable ?

Most HV cables have a armour and a screen around the 3 core cable or a screen around each individual core.

A photo would be nice.
Posted By: Trumpy Re: High voltage? - 01/26/08 09:23 PM
Here's the picture:

[Linked Image from]
Posted By: leland Re: High voltage? - 01/27/08 02:59 AM
Thanks for the photo Mike.

Basicaly behind the sheet metal cover, all the boots are made up and the sheilds terminated and bonded to the frame.
However the conduits are not bonded to the frame (just filled with sealant to keep the water from man holes out).
I would think they should be.
Posted By: Yoopersup Re: High voltage? - 01/27/08 03:22 PM
Try 250.190 2005 nec
Posted By: electure Re: High voltage? - 01/28/08 12:25 AM
Just ductseal in the conduits?
2005 NEC RMC
344.46 Bushings. Where a conduit enters a box, fitting, or other enclosure, a bushing shall be provided to protect the wire from abrasion unless the design of the box, fitting, or enclosure is such as to afford equivalent protection.

So if it doesn't ENTER the box, fitting, or other enclosure, this doesn't apply??
Posted By: SteveFehr Re: High voltage? - 01/28/08 11:48 AM
I agree with Yoopersup. Regardless of any HV specific clauses, 250.190 requires any metal that's likely to become energized must be bonded to the building ground, which implicitely requires the cabinet and conduits be bonded to a common point.
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