Exterior breaker panel installation

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jjhoward

jjhoward

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Location
Northern NJ
Occupation
Owner TJ Electric
Can someone supply real life experience with the installation of an exterior breaker panel mounted on the outside wall of a house? I am sizing up a service upgrade on a little 2 room bungalow and the only place I can see for the new panel is on an outside wall. Where do the branch circuits enter an exterior breaker panel?
Thanks
 
Re: Exterior breaker panel installation

one major question where are you deriving power for this panel is this going to be a lighting and appliance circuit panel?
 
Re: Exterior breaker panel installation

This is going to the one and only panel for this house. Service drop conductors through the meter pan into this service panel. That is it. The branch circuits that are now in the old 60 amp breaker panel must be re-routed to this new 100 amp panel.
 
Re: Exterior breaker panel installation

NEMA 3R panel, of course. Wiring enters the back of the panel.
One method was to install a bushing, then run all romex into panel. HOWEVER, this is a code violation because the romex is not secured to the panel. Talk to your AHJ or another electrician in your area for what is acceptable in your area!

I have used this in the past: PVC straight up from top of panel using panel hub, to LB, then into attic, to a large j-box. All romex was connected to j-box. THHN through PVC to panel, terminated on breakers.

(Local code did not require derating in residential applications.)
 
Re: Exterior breaker panel installation

Hi Tshea,
Thanks for the reply. Yes this will be NEMA 3R load center. I am wondering if I need to frame out the area where I will mount the box to accomodate the clamps for the ROMEX branch circuits for through the back entry. The PVC out the top or bottom could be another solution. Need to discuss with the inspector. Do exterior load centers have knock outs on the back surface?
 
Re: Exterior breaker panel installation

T-shea,

If the panel is outdoors, isn't it a wet location and THWN should be used?

Mark
 
Re: Exterior breaker panel installation

From Tshea, "I have used this in the past: PVC straight up from top of panel using panel hub, to LB, then into attic, to a large j-box. All romex was connected to j-box. THHN through PVC to panel, terminated on breakers."

This installation method is a violation of 312.5(C)Exception.

(b)The raceway extends directly above the enclosure and does not penetrate a structural ceiling.
 
Re: Exterior breaker panel installation

THWN should be used
Click to expand...
Use dual rated THHN/THWN

This installation method is a violation of 312.5(C)Exception.

(b)The raceway extends directly above the enclosure and does not penetrate a structural ceiling.
Click to expand...
Does not apply. PVC conduit is run from the top of the panel to an LB which penetrates the wall, then PVC is continued to a junction box-using all appropriate fittings, fasteners, etc.
The junction box-properly sized for the amount of wires, etc. is in the attic. The romex is physically attached to the j-box. Inside the j-box are wire nuts used to splice to single conductor wire which is then run into the panel.
ROMEX is NOT pushed through the PVC.
 
Re: Exterior breaker panel installation

Where is the old panel right now. Is there a reason why you can put the new one in place of the old.

Just curious..

Otherwise I have always used a large j-box or troft as explained by others. The same can be done going into the basement.

Just realize if you are just doing an upgrade you are creating more work by relocating it. You will not only have to J-box all the wires at the new panel but also where the old panel is. I guess if its only an little two room place you may not have many ckts.

I would also look into the newer meter/load center combo packs that most manufactures make for trailer and temp service type of applications. This will save you time and money since it is one self contained unit.
 
Re: Exterior breaker panel installation

Hello CopperTre,
The existing panel is 8 breakers in a square D box ..get this..in a wall BEHIND a kitchin cabinet about 1' from the sink.
So...yes, we are installing the new service equipment somewhere else. But this 3 room house really doesnt have any place for a panel so out on the front porch it goes.
 
Re: Exterior breaker panel installation

jj, Is the panel on a exterior wall? Or is there a posibility of installing the panel in the same spot but on the other side of the wall?
 
Re: Exterior breaker panel installation

Originally posted by pierre:
[QB] From Tshea, "I have used this in the past: PVC straight up from top of panel using panel hub, to LB, then into attic, to a large j-box. All romex was connected to j-box. THHN through PVC to panel, terminated on breakers."

I assume your pipe run is longer than 24", so by the time you run all your circuits in this conduit and properly derate them, I bet you have to run a #10 wire for a 15 amp circuit.
Click to expand...
 
Re: Exterior breaker panel installation

I assume your pipe run is longer than 24", so by the time you run all your circuits in this conduit and properly derate them, I bet you have to run a #10 wire for a 15 amp circuit.
Click to expand...
How much would you have to de-rate 8 ckts? Thats 12 wires. We have run 15 #12's in 3/4 emt about 100' time and time again.

JJ, I really wouldnt worry about de-rating in your case.
 
Re: Exterior breaker panel installation

How much would you have to de-rate 8 ckts? Thats 12 wires.
Click to expand...
If you properly share a neutral between 2 circuits, you only have 8 current carrying conductors and you would have to derate to 70% of the conductor capacity. If you pulled seperate neutrals for each circuit, that would be 16 conductors and you would derate to 50% of the conductor capacity. I once went behind someone that did not understand the requirements for sharing a neutral (the circuits must be on different phases) and he had two circuits on the same phase sharing a neutral. Neutral current was over 30 amps (#12 wire).

We have run 15 #12's in 3/4 emt about 100' time and time again.
Click to expand...
If all 15 #12's are current carrying, you must derate to 50% of the conductor capacity.


JJ, I really wouldnt worry about de-rating in your case.
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JJ, do yourself a favor and read 310.15(B)(2) and look at table 310.15(B)(2)(a) and decide for yourself if you need to worry about derating.
 
Re: Exterior breaker panel installation

We wire only to 70% cap on every ckt we pull. If you go by that common rule of thumb you wont have many problems. I don't know many ec that put 100% on any one ckt.

I wouldn't place 15 current carrying #12s in a 3/4" pipe because that would mean I would have 8 nuturals in a 1ph system or 5 in a 3ph system. That would put me just a bit of the 16 conductor max on the pipe.

I dont feel a need for JJ to worry about de-rating on 8 residential ckts. If I was him I would run a 1-1/4" between the panel and j-box so he has spare room for future use.

And I still don't thing you need to worry about de-rating in the application...
 
Re: Exterior breaker panel installation

I assume your pipe run is longer than 24", so by the time you run all your circuits in this conduit and properly derate them, I bet you have to run a #10 wire for a 15 amp circuit.
Click to expand...
8 circuits (multi-wire)= 12 conductors, derate 50% use 90 degree column, #12 AWG THHN/THWN is OK. #10 is over-kill.

(Local code did not require derating in residential applications.)
Click to expand...
from original post.
 
Re: Exterior breaker panel installation

Thank you all for the input.
For those still interested here's how we did this job:
Exterior NEMA 3R panel (just no place in the house for an interior mnt.)
Different wall that the existing panel because the service drop needed to be moved as well. Old location had it hooked to the roof such that the service drop was contacting the roof ridge and then the breakout of the 3 conductors layed on the roof then over the edge to the service entrance conductors.
We ran old wires into a jbox in the attice above the old location, ROMEX to another jbox above the new site. Liquid tight conduit down the wall to the new exterior box, all connected at the rear of the box. We had to drill some holes of own into the back of the panel for the connections.
THWN wires oversized: 10awg for 20 amp circuits from the panel to the jbox, 12 awg for the 15 amp circuits. Backfeeding the new box from the old wires (8 awg on a dp 40 amp breaker)until the utility co moves the service feed.
Thanks again for the input.
 
Re: Exterior breaker panel installation

Hello Copper,
I could not get the local AHJ on the phone for a discussion and I could not find anything clear in the NEC that said NOT to derate 4 or more conductors in a conduit. I needed to get it done and I don't want to give the AHJ any reason to give me a bright orange sticker, I like the white ones better. :D
 
Re: Exterior breaker panel installation

I for one do not see the derating need in the NEC for dwellings as needed as much as others. With the exception of certain dedicated circuits and maybe some large circuits like ranges, air conditioners, and dryers. This has been a problem on houses with runs out of the panel that have to run through bored holes in the floor joist which when dealing with TGI's or other manufactured joist limit how many holes you can have. I just don't see the derating need for most circuits?
I have a proposal that I plan to submit in September on this and can be seen here:
Topic: 310.15(B)(2) add Exception 6.

Still under tweeking. :D

[ March 06, 2005, 03:15 AM: Message edited by: hurk27 ]
 
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