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CT cabinet with only 2 CT's in it #184299
02/06/09 05:46 PM
02/06/09 05:46 PM
trekkie76  Offline OP
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.
Edited to add code section

Last edited by trekkie76; 02/06/09 05:51 PM.
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Re: CT cabinet with only 2 CT's in it [Re: trekkie76] #184301
02/06/09 06:53 PM
02/06/09 06:53 PM
HotLine1  Offline

Joined: Apr 2002
Posts: 6,935
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

Re: CT cabinet with only 2 CT's in it [Re: trekkie76] #184302
02/06/09 07:24 PM
02/06/09 07:24 PM
LarryC  Offline
Joined: Jul 2004
Posts: 783
Winchester, NH, US
Corner grounded Delta system?

Larry C

Re: CT cabinet with only 2 CT's in it [Re: LarryC] #184306
02/06/09 08:45 PM
02/06/09 08:45 PM
Trumpy  Online Happy

Joined: Jul 2002
Posts: 8,236
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?

Re: CT cabinet with only 2 CT's in it [Re: Trumpy] #184307
02/06/09 09:25 PM
02/06/09 09:25 PM
JoeTestingEngr  Offline
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.

Re: CT cabinet with only 2 CT's in it [Re: JoeTestingEngr] #184309
02/06/09 09:59 PM
02/06/09 09:59 PM
ameterguy  Offline
Joined: May 2002
Posts: 30
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.

Re: CT cabinet with only 2 CT's in it [Re: ameterguy] #184326
02/07/09 07:34 AM
02/07/09 07:34 AM
frenchelectrican  Offline
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 }


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 07:37 AM. Reason: add more info

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

Re: CT cabinet with only 2 CT's in it [Re: frenchelectrican] #184328
02/07/09 01:52 PM
02/07/09 01:52 PM
HotLine1  Offline

Joined: Apr 2002
Posts: 6,935
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.

Re: CT cabinet with only 2 CT's in it [Re: HotLine1] #184340
02/07/09 05:08 PM
02/07/09 05:08 PM
RODALCO  Offline
Joined: Dec 2005
Posts: 856
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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