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12470 disconnect switches #174031 01/25/08 02:07 PM
Joined: Mar 2003
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Yoopersup Offline OP
Member
12470 feeds two 2500 kva transformers. Service point Line side of disconnect. So under NEC . One disconnect for both transformers or one disconnect for Each transformer?? If it was Power Co.owned they'd use one for both . But nec ???
230.200 NEC"s a start. Also another interesting Question are disconnects grounded?? If so How??By the way theses switches are outdoors. about 150 ft from transformers.

2017 / 2014 NEC & Related Books and Study Guides
Re: 12470 disconnect switches [Re: Yoopersup] #174081 01/26/08 12:00 AM
Joined: Jan 2004
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George Little Offline
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Okay Ernie— The rules for less than 600v. apply based on 230.200. The disconnect(s) will be "Service Disconnect(s)" and there are no Service Entrance Conductors. The overcurrent protection must be an integral part of the disconnect(s) or be immediately adjacent 230.91. The conductors feeding the xformers are feeders and the rules for overcurrent protection found in 240.101 apply. As for the grounding, the GEC will be the ground for the Service Disconnects and will be sized per 250.66 Note 2. As for 1 or 2 Disconnects I think either would work and which ever would cost less would probably prevail.

This is my opinion and I hope I've not missed something.
Hey Ernie- You going to Holland?


George Little
Re: 12470 disconnect switches [Re: George Little] #174115 01/26/08 10:40 PM
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George Little Offline
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Ernie— After reading your post and my response, I think I might have assumed something and maybe my answer was not appropriate. Are the transformers customer owned? Where is the disconnect switch(es) in the system? What is the voltage Primary & Secondary of the transformers?


George Little
Re: 12470 disconnect switches [Re: George Little] #174120 01/27/08 12:09 AM
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Yoopersup Offline OP
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George
Power Co. Line 12470 three phase . Customer owns both transformers. Disconnect Switch or switches (fused) where Power Co. Comes off Pole . Aprox. 100 ft to transformers. Secondary of transformers 480/277.

Re: 12470 disconnect switches [Re: Yoopersup] #174189 01/28/08 08:05 PM
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George Little Offline
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Ernie- If the switch(es) are customer owned I'm sticking with my answer. Still not sure but since you said the "Service Point" is the terminals on the line side of the switch(es), it sounds like the switch(es) are customer owned.


George Little
Re: 12470 disconnect switches [Re: George Little] #174242 01/30/08 12:08 AM
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Posts: 849
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Yoopersup Offline OP
Member
Service point top of Pole at utility co. cutouts.

Re: 12470 disconnect switches [Re: Yoopersup] #174277 01/30/08 11:03 PM
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George Little Offline
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Ernie— I'm starting to get the picture now with your added information. Your first post said the Service point was the "line terminals of disconnect".

The pole top cutouts do not qualify as a Service Disconnect based on 230.70. You were saying that the Service Point is at the line terminals of the disconnect switch - apparently the pole top cutouts is what you were referring to. This would mean the conductors after the pole top cutouts are customer owned and the the conductors are Service Entrance conductors that need a Service Disconnect that complies with 230.70. I suspect that the cutouts are utility owned.

I don't see anyone making any comments so maybe the answer is forthcoming from others. I've never had to inspect a service like this so maybe I can learn something.

Last edited by George Little; 01/30/08 11:04 PM.

George Little
Re: 12470 disconnect switches [Re: George Little] #174303 02/01/08 10:28 AM
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JBD Offline
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Are there individual fuses for each transformer per(A)?

If the conductors to each transformer are feeders are they protected as required by 240.100?

If the conductors to each transformer are service conductors are they protected per 230.208?

At the service disconnect point does the disconnect device simultaneously open all ungrounded conductors per 230.205?

Does the service disconnect have visible blades per 230.204?



Re: 12470 disconnect switches [Re: JBD] #174336 02/02/08 12:55 AM
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Yoopersup Offline OP
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See Page 230.200 Exhibit 230.31. Thats the way it is. the disconnects are remote from the transformers line sideas per 230.204 (B)location per 230.205(A) which refers you to 230.70 (A)
Load side of transformers Disconnect switchs in Building Nearest point of entrance 240.21 (C) 4.

Re: 12470 disconnect switches [Re: Yoopersup] #174350 02/02/08 11:29 AM
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George Little Offline
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Ernie I guess you meant page 155 in the '05 handbook. This is what I said earlier— The Service Disconnect is missing in your posted question. You will need a Service Disconnect and fuses just like what is shown in Fig. 230.31
Must meet the requirements for "Readily Accessible" per 230.70(A). The Depending on some of the other factors ie: wire size and fuses and ownership you might need two switches and two sets of fuses.


George Little
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