Considering installing a subpanel

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  #1  
Old 02-26-11, 11:15 AM
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Considering installing a subpanel

At present , in my main panel, I have a 14 gauge wire connected to a 15 amp breaker. This wire goes and feeds a electrical junction box that has the some additional wires joined to it there. Tracing these out I found that these feed a sump pump, some outdoor spots, and two outdoor outlets. When one has a problem it is tedious to find the culprit and fix it, Plus that box looks a little tight!
-I am thinking of breaking these up into seperate circuits through a subpanel. I presently am thinking of changing the breaker wire to a 12gauge (10?) and leaving the 15 amp breaker.
-This would feed a GE TLM612F1 (brand new)panel that I have available and use that as a sub. May be panel overkill but it is still new, in the box and was to be part of another non-completed modification.
-At the panel I would break the circuit into 15 amp circuits on their own breakers.
Any ideas or suggestions as to whether I should up the 15amp supply to 20 and would I need a 20amp main cutoff breaker at the sub or a simple on/off cutoff ?
 
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Old 02-26-11, 11:53 AM
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Multiple ways to do this but this is what I'd do.

I'd replace the J box with the subpanel. Move all cables from the junction box to the subpanel.

I'd abandon the #14 cable and remove the 15 amp breaker from the main panel. Install a 40a 240v breaker at the main and run 8-3 NM-b to the sub.

Remember at the sub you will need a bonded ground bar and an isolated neutral bar. The panel may not have a ground bar. If so you will need to install one. As long as there are 6 breakers or less you don't need a main breaker at the subpanel. If you do use a main breaker in the subpanel it should be 40 amps or larger.

Edit: I was incorrect about the need for a main breaker. See Furd's reply below.
 

Last edited by ray2047; 02-26-11 at 02:49 PM. Reason: Correct information.
  #3  
Old 02-26-11, 12:41 PM
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If the sub-panel is in the same building as the Service (main) panel the sub does not need a main breaker regardless of how many branch circuit breakers are installed.
 
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Old 02-26-11, 01:17 PM
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Thanks

Thanks again Furd!

The sub. will indeed be within the same building, and may be only a few feet from the main.
Ray was expressing the main thoughts that I was contemplating, except for the 40 amp breaker. Didn't even think that large.
I just rechecked and the circuit is protected by a 20 amp CB, not a 15amp CB. Always good to have a better flashlight, and glasses ON, when checking breaker size!
So would a 40 be overkill and a 30 be okay? I know, if can go for it! Just that these are all maybe 20 amp circuits at most and I don't believe that any heavy draw items will be placed on it.
 
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Old 02-26-11, 02:53 PM
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I was shooting for the overkill to allow for future needs unknown. Not much difference in cost between 10 and 8. If you wanted you could still use a 30a breaker at this time. I'd suggest adding up the actual loads that might be on at any one time.
 
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Old 02-26-11, 05:53 PM
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Also, 14awg can be on a breaker no larger than 15A
12awg can be on a breaker no larger than 20A
 
  #7  
Old 02-27-11, 08:39 AM
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Thanks guys. Time to add up, and head out. One other question. I believe that the 30inch location rule also applies to subs, Am I correct on that?
 
  #8  
Old 02-27-11, 08:46 AM
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You would still need to have the same clear workspace as the main panel.
 
  #9  
Old 03-12-11, 01:44 PM
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Started to work on this and was mapping things out. Question arose that may sound silly.
Do the main panel supply CBs have to be adjacent to each other to feed the sub? At present the slots used would be #2 and 30 in a Square D Q0C30U to feed a GE TLM612F1 subpanel.
Using 8/3, I would run either red or black (from #2 & 30 slots open for supply) to the sub main lugs connections without main (input)CBs at the sub.
If not, I would use 8/2 and jumper, at the sub, to both main lugs and label the panel 120 ONLY.
Would I need CBs at the sub main lug if I was to do the latter?
Is either one feasible and correct?

Just some questions that arose do to reading something at another site that sounds confusing.
 

Last edited by Bob M; 03-12-11 at 01:45 PM. Reason: spelling
  #10  
Old 03-12-11, 06:32 PM
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You definitely need two adjacent spaces and a 2 pole breaker. In your case, you'll need a QO240 2 pole 40 amp breaker and 8-3 NMB cable.
 
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