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#184299 - 02/06/09 04:46 PM CT cabinet with only 2 CT's in it  
trekkie76  Offline
Member
Joined: Jun 2004
Posts: 220
baileyville, maine, usa
[Linked Image]

I found this photo on the internet and am wondering why 2 things.

1. Why is there only 2 CT's, with the B phase unmetered?
2. If the color code is right, this is a 208Y/120V 4 wire system. Where is the grounded(neutral) conductor? Isn't this a violation of 250.24(C)?
I have never seen a CT cabinet that didnt have a CT for each phase. Maybe someone could steer me in the right direction.
Thanks,
Gary
Edited to add code section

Last edited by trekkie76; 02/06/09 04:51 PM.

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#184301 - 02/06/09 05:53 PM Re: CT cabinet with only 2 CT's in it [Re: trekkie76]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,874
Brick, NJ USA
Disregarding the 'color code'.....600 volt fuses in disco, looks like 3 phase, 3 wire (delta) 480 volt service.

I only came accross this twice, a long time ago; industrial


John

#184302 - 02/06/09 06:24 PM Re: CT cabinet with only 2 CT's in it [Re: trekkie76]  
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
Winchester, NH, US
Corner grounded Delta system?

Larry C


#184306 - 02/06/09 07:45 PM Re: CT cabinet with only 2 CT's in it [Re: LarryC]  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,223
SI,New Zealand
Shouldn't that CT enclosure and the meter base enclosure also have a ground wire attached to them and run back to that ground wire in the Disconnect?


#184307 - 02/06/09 08:25 PM Re: CT cabinet with only 2 CT's in it [Re: Trumpy]  
JoeTestingEngr  Offline
Member
Joined: Nov 2005
Posts: 791
Chicago, Il.
Whether corner grounded or not, don't 2 CTs give you all you need on a delta??? Not true with a wye.
Joe


#184309 - 02/06/09 08:59 PM Re: CT cabinet with only 2 CT's in it [Re: JoeTestingEngr]  
ameterguy  Offline
Member
Joined: May 2002
Posts: 30
Mass
A Delta service is metered with two CTs. The service being either corner grounded or not, does not change the metering setup.
The picture also shows a three phase, four wire meter socket. I think either the CT configuration is wrong or the socket is wrong.


#184326 - 02/07/09 06:34 AM Re: CT cabinet with only 2 CT's in it [Re: ameterguy]  
frenchelectrican  Offline
Member
Joined: Feb 2003
Posts: 939
Wi/ Paris France { France for ...
The only other possiblty when you see two CT's there it possbilty that is used for electric motor load only { I did see it in few place like that however POCO don't like it much }

Merci,Marc

P.S. look like 60 a 240 or 208 volt otherwise 480 v 30 amp due the conductor size looks pretty small.

Last edited by frenchelectrican; 02/07/09 06:37 AM. Reason: add more info

Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)


#184328 - 02/07/09 12:52 PM Re: CT cabinet with only 2 CT's in it [Re: frenchelectrican]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,874
Brick, NJ USA
Looks like max 30 amp fused disco at 480/600 volt as I look again.

POCO here supplies CT's and meter pan, and installs wiring from CT's to pan.



John

#184340 - 02/07/09 04:08 PM Re: CT cabinet with only 2 CT's in it [Re: HotLine1]  
RODALCO  Offline
Member
Joined: Dec 2005
Posts: 854
Titirangi, Akld, New Zealand
It looks like an overkill to me for CT metering.
That size cable looks like 16 or 25 mm˛ and the power usage could have been metered directly with a whole current meter.

This CT set up adds hugely to the overall installation costs.


The product of rotation, excitation and flux produces electricty.


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