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Old 06-05-2010, 01:11 PM   #1
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Sub panel instalation


want to clear up a few last minute questions.
I am installing a sub pannel. It is a 100 amp pannel, but for now, It will be powered off of a 60 amp breaker in one of the mains. Initialy I only plan a 40 amp and 20 amp 240 volt breakers in the pannels for a pool heatpump and the circulating motor. I'll probably eventually tie in the "local" 120 volt circut to this pannel, but for now its working, so I wont mess with it.

The sub pannel is an outdoor Cutler Hammer that came with a 100 amp main breaker and a seperate lug block. It looks like a breaker, but has no switch (I think there might be a 150 amp fure inside, but I'm not sure). I know the pannel is overkill, but it is what was available in weatherproof.

I assume I'd use the lug block in this instance because the 60 amp breaker in the house would be the main breaker here.

I am running 4 wires, so I was told to keep the neutral and the ground seperate, and don't do a grounding rod.
Does that sound right?

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Old 06-06-2010, 12:25 AM   #2
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Sub panel instalation


For clarification, where is the sub panel located - same or differing building as the main panel?

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Old 06-06-2010, 07:19 AM   #3
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Sub panel instalation


my research is telling me I need a couple of grounding rods. Thats what I thought, but the home improvement guy said no.

Sub is in a pool shed with a 150' run from the main (and its looking like I should have picked up 152') the shed is about 60' from the nearest corner of the house (of course the mains are on the far corner)
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Old 06-06-2010, 09:35 AM   #4
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Sub panel instalation


Detached structures require ground rod and separate disconnect - usually a main breaker panel is used with the main breaker as the disconnect.

Not understanding your comment of "The sub pannel is an outdoor Cutler Hammer that came with a 100 amp main breaker and a seperate lug block. It looks like a breaker, but has no switch (I think there might be a 150 amp fure inside, but I'm not sure)."
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Old 06-06-2010, 09:37 AM   #5
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Sub panel instalation


Detached building needs 2 ground rods 6' apart for a sub
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Old 06-07-2010, 12:44 PM   #6
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Sub panel instalation


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Originally Posted by vsheetz View Post
Detached structures require ground rod and separate disconnect - usually a main breaker panel is used with the main breaker as the disconnect.

Not understanding your comment of "The sub pannel is an outdoor Cutler Hammer that came with a 100 amp main breaker and a seperate lug block. It looks like a breaker, but has no switch (I think there might be a 150 amp fure inside, but I'm not sure)."
It looks like they are setting it up to work as either a regular fuse pannel, or as a sub pannel.
There would seam to be 2 options for hooking it up. 1st beaing the main, and 2nd what I am calling the lug block. It looks like a 240volt breaker, but has no switch
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Old 06-07-2010, 01:01 PM   #7
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Sub panel instalation


What you are calling a lug block is designed for feed-thru from the new CH panel. Feed the panel through the main. If you use the lug block to feed-thru the panel the wirinng ampacity must be as great as the incoming feed. There is no OCPD inside the lug block.
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Old 06-07-2010, 10:49 PM   #8
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Sub panel instalation


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Originally Posted by brric View Post
What you are calling a lug block is designed for feed-thru from the new CH panel. Feed the panel through the main. If you use the lug block to feed-thru the panel the wirinng ampacity must be as great as the incoming feed. There is no OCPD inside the lug block.
Huh?
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Old 06-16-2010, 10:46 PM   #9
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Sub panel instalation


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Detached building needs 2 ground rods 6' apart for a sub

I thought thats only if you use 3 wire for service......
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Old 06-16-2010, 11:31 PM   #10
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Sub panel instalation


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Originally Posted by LyonsElecSupply View Post
I thought thats only if you use 3 wire for service......
and no, you need a ground rod regardless at the detached building.

only 1 is required if you can prove less than 25 ohms resistance. Since not too many people want to go to that effort, you simply drive a second rod. The code does not specify any particular resistance at that point.



and when installing ground rods, they need to be at least 6 feet apart. They are more effective if they are placed at least their height apart from each other. As such, I recommend placing an 8 foot rod at least 8 feet from any other rod, 10" rod, 10' from another rod, and so on.
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Old 06-16-2010, 11:34 PM   #11
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Sub panel instalation


Quote:
Originally Posted by brric View Post
What you are calling a lug block is designed for feed-thru from the new CH panel. Feed the panel through the main. If you use the lug block to feed-thru the panel the wirinng ampacity must be as great as the incoming feed. There is no OCPD inside the lug block.
what about the protection afforded by the main in the subpanel. Are you saying even with a breaker in the sub, you still have to run wire to meet the rating of the main in the panel it is fed from?

what would you do if you used a feed through panel?
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Old 06-17-2010, 02:43 AM   #12
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Sub panel instalation


Either i was unclear or I was misunderstood. For instance, if a feed-thru panel with a 100 amp main breaker is fed with 100 amp rated conductors, one may feed-thru such panel with 100 amp rated conductors without putting the feed-thru conductors on a breaker as they are already protected by the 100 amp main of the feed-thru panel.
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Old 06-17-2010, 06:42 PM   #13
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Either i was unclear or I was misunderstood. For instance, if a feed-thru panel with a 100 amp main breaker is fed with 100 amp rated conductors, one may feed-thru such panel with 100 amp rated conductors without putting the feed-thru conductors on a breaker as they are already protected by the 100 amp main of the feed-thru panel.
What I understood your statement to be was that even with a 50 amp main breaker in the subpanel, if using a feed through panel or lug to feed that sub, you would have to run wire to match the main breaker in the main panel.(100 amp in the situation above)

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