Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 02-27-2013, 06:47 PM   #1
Newbie
 
Join Date: Feb 2013
Posts: 26
Rewards Points: 25
Default

Question regarding new load center on cinder block wall.


Hello DIY gang,

Background:

I'm well into the remodeling of my guest house and am pulling the wire through the framing now. I have a 100 amp metered box (with a 100 amp breaker) on the main house specifically for the guest house. Right next to it on the main house is the second meter for the main house. So basically the guest house has its own and independent power.

I have run a line mostly underground in conduit with appropriate copper wire more than capable to carry the 100 amps from the main house to the guest house. Now the conduit ends in a load center / breaker box (with a 100 amp breaker also). An electrician helped me out with this.

This load center is mounted on the guest house outside which is constructed of hollow cinder block with stucco. I have chiseled out a decent sized hole through the cinder block (approximately 2" x 4") that lines up with the back of the load center. I have knocked out a 2" hole in the load center that lines up with the hole in the wall. The 2" knock out has a plastic ring to prevent cutting wire pulled through it, but nothing else.

This load center is situated under a patio roof so it won't receive direct rain.

Questions:

#1 As expected, there is a small gap of maybe 1/8 to 1/2 inch between the load center and the stuccoed wall. This gap allows air and the weather to get into both the load center and into the guest house through the hole knocked through the wall. I have heard opposing stories as to whether or not I can seal the gap. I was thinking of stuccoing in the load center or using expanding foam to seal it. Neither would touch the wire. What are your thoughts?

#2 Do I need a short 8" piece of conduit to run through the wall or can I directly pull the Romex through the wall into the load center?

#3 if no conduit is used, what is the maximum number of Romex 12/2 cables that can safely be fed through a 2" hole?

#4 If I were to strip off the outer shell of the Romex before it entered the breaker box. I'm assuming this is not recommended. What are your thoughts?

I will hire an inspector to check my work when I am done, but I would like to have it correct and safe before he comes. Up to code (NEC 2008) is desirable. That is what the city follows.

I have photos of the inside and outside uploaded here:

http://imgur.com/aqf02xD

http://imgur.com/ENizESI

Thanks, Chris.

chris_b is offline   Reply With Quote
Old 02-27-2013, 07:19 PM   #2
Semi-Pro Electro-Geek
 
Join Date: Jul 2009
Location: Arizona, USA
Posts: 2,559
Rewards Points: 2,014
Default

Question regarding new load center on cinder block wall.


1: Seal around the hole. It is required - otherwise the wires, the panel, and the inside of the wall would be subject to weather. Do not get sealant all over the wires, just seal around the hole. Use plenty of silicone caulk. If the gap is huge, use some foam - but it won't take much!

2: No conduit is needed or advisable, assuming the cable is going directly from the panel into the wall cavity. It is common practice in many areas to run large numbers of NM cables through single holes into breaker panels without strain relief connectors - although this often technically violates one or more code rules regarding securing cables, closing penetrations in panels, or bundling/derating conductors. See below...

3: If all the cables are running through the same hole, and then up the same cavity in the block wall, you may be subject to derating requirements. If you have them "bundled" together for any significant distance, this will be a problem. How many cables are there, where do they go, and how do they get there from the panel?

4: This is not allowed. The sheath must extend into the panel.

__________________
I am a lawyer, but not your lawyer. And who cares anyways? We're here to talk construction. This is DIY advice, not legal advice.
mpoulton is offline   Reply With Quote
Old 02-27-2013, 08:34 PM   #3
Electrical Contractor
 
rrolleston's Avatar
 
Join Date: Oct 2011
Location: Granville, NY
Posts: 1,941
Rewards Points: 1,000
Send a message via AIM to rrolleston Send a message via Yahoo to rrolleston
Default

Question regarding new load center on cinder block wall.


If you have that green bonding screw in there you should remove it. Not allowed to have the ground and neutral bonded in a sub panel.
__________________
With Electricity there is the right way to do it and the dead way. Just because it works does not make it safe.
rrolleston is offline   Reply With Quote
Old 02-27-2013, 10:40 PM   #4
Newbie
 
Join Date: Feb 2013
Posts: 26
Rewards Points: 25
Default

Question regarding new load center on cinder block wall.


Thank you for the very helpful replies.

rrolleston, yes we do have the screw in there and will take your advice. Originally there was a thick wire that connected the neutral and the ground. That's how the load center came out of the box. The electrician I hired to help took the connecting wire out and tightened down the green screw. Thank you for your observation.

BTW, there is one ground rod at the main house for this load center and no second rod. I will be adding a second rod and can get it at least 10 or 15 feet away. Should I add the second ground rod at the sub panel on the guest house or the source panel 50 feet away on the main house? Maybe both for a total of 3 rods?

mpoulton, Thank you for your input also. It was just the info I was seeking. The cables are going directly from the panel through the hole in the wall (8 inch thick hollow cinder block) and once it breaks inside the house, all of the cables will fan out. None of the cables will be bundled together, however they will all be going through the same 2" hole in the panel back unless I don't have capacity. In that case I will make a second hole in the wall inside the breaker box, and use a 90 degree type elbow and conduit to take some of the wires through the new hole. I estimate the total length of this second conduit to be about 6 to 8 inches. If I add the second hole I will use conduit somewhere between 2" and 3" in diameter.

I have a lot of cables for this somewhat small 600 sq ft guest house, but I'm trying to keep the load on each line low. The place will have a full kitchen, bathroom, tiny laundry for a small over / under machine, and electric water heater, smaller electric range, and mini split AC. No gas in the house.

In total I am planning on having these separate circuits / lines hooked up to this breaker box:

12 X 12/2 Romex 20 amp
2 X 8/3 over sized for 30 amp
1 X 6/3 over sized for 40 amp

Given all of the wire I am concerned it won't all fit through one 2" hole so I may need a second.


Thanks!

Last edited by chris_b; 02-27-2013 at 11:02 PM.
chris_b is offline   Reply With Quote
Old 02-27-2013, 10:57 PM   #5
Newbie
 
Join Date: Feb 2013
Posts: 26
Rewards Points: 25
Default

Question regarding new load center on cinder block wall.


rrolleston, I want to make I understand this correctly.

Right now, the neutral bar in the subpanel box does not touch either the box its self nor is it jumped over to to the ground bar. It only goes back to the main breaker box at the meter. The ground bar is attached to the subpanel box with the green screw. It sounds like you are suggesting I not attach the ground to the box. Is this correct?

Or are you just making sure that both the neutral and ground bars are not both connected to the box? If so, my neutral bar is not touching the subpannel.

This link seems to suggest the way I currently have it is correct in the section titled "Grounding and bonding of the sub-panel". Since my understanding of your comment is not certain, I just want to make sure I am understanding things correctly.

http://ths.gardenweb.com/faq/lists/w...726007600.html

Thanks!
chris_b is offline   Reply With Quote
Old 02-28-2013, 12:52 AM   #6
Member
 
Join Date: May 2008
Location: Apple Valley, MN, USA
Posts: 1,002
Rewards Points: 506
Send a message via AIM to theatretch85
Default

Question regarding new load center on cinder block wall.


The neutral and ground bars should not be tied together, but the ground bar should be bonded to the panel with the green screw as you have it now. Leave the green screw in.

With the 2" hole going through the wall, I'd highly suggest using a short piece of electrical PVC (the gray stuff) with the proper fitting and extending it fron the panel through the entire thickness of the concrete block wall (and maybe protrude into the stud wall just a 1/4" -1/2"). This would make things a lot easier to seal up around the hole in the brick and provides a much easier path for running the cables into the panel. It is my understanding you don't have to worry about de-rating until the conduit is longer than 2 feet.

Also, as for the sealant around the wires themselves inside the conduit hole, traditionally Duct Seal is used. It is a putty like block and usually sells for less than $2 for a 1lb block at most hardware stores and it seals the passage of warm/cool air and helps prevent condensation from forming on either side. Duct seal should be used on any pipe through the wall from an outside space to an inside space.
theatretch85 is offline   Reply With Quote
Old 02-28-2013, 07:45 AM   #7
Electrical Contractor
 
rrolleston's Avatar
 
Join Date: Oct 2011
Location: Granville, NY
Posts: 1,941
Rewards Points: 1,000
Send a message via AIM to rrolleston Send a message via Yahoo to rrolleston
Default

Question regarding new load center on cinder block wall.


Yes that was my mistake I notice now that both bars are on the plastic plate and yes the green screw is needed to bond the ground to the metal of the panel.

But you probably need ground rods if this is a detached building.
__________________
With Electricity there is the right way to do it and the dead way. Just because it works does not make it safe.
rrolleston is offline   Reply With Quote
Old 02-28-2013, 12:43 PM   #8
Newbie
 
Join Date: Feb 2013
Posts: 26
Rewards Points: 25
Default

Question regarding new load center on cinder block wall.


Thank you theatretch85 & rrolleston,

I am glad to hear the short distances in conduit of approximately 8 inches is not a worry for derating purposes. I do like the idea of keeping the wires clean in a small grey PVC pipe and this will guarantee a good clean seal both between the box and the wall (with caulk / foam) and in addition in the pipe I'll get and use the Duct Seal.
chris_b is offline   Reply With Quote
Old 02-28-2013, 02:45 PM   #9
Licensed electrician
 
Join Date: Sep 2007
Location: Maryland
Posts: 7,837
Rewards Points: 2,472
Default

Question regarding new load center on cinder block wall.


I cannot think of a code compliant way to bring all those cables into a panel mounted on the exterior of the wall. The method described would certainly not pass near me. I have seen pictures where this seems to be commonly accepted.
__________________
Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.
Jim Port is online now   Reply With Quote
The Following User Says Thank You to Jim Port For This Useful Post:
stickboy1375 (02-28-2013)
Old 02-28-2013, 03:01 PM   #10
Newbie
 
Join Date: Feb 2013
Posts: 26
Rewards Points: 25
Default

Question regarding new load center on cinder block wall.


Jim Port,

Do you think it would be a better idea to run one or more conduits out the side of the breaker box and then use something like 90 degree pull elbows and then enter the house that way?

Thanks.
chris_b is offline   Reply With Quote
Old 02-28-2013, 03:32 PM   #11
Semi-Pro Electro-Geek
 
Join Date: Jul 2009
Location: Arizona, USA
Posts: 2,559
Rewards Points: 2,014
Default

Question regarding new load center on cinder block wall.


Quote:
Originally Posted by Jim Port View Post
I cannot think of a code compliant way to bring all those cables into a panel mounted on the exterior of the wall. The method described would certainly not pass near me. I have seen pictures where this seems to be commonly accepted.
Just curious: do you commonly use exterior panels on residences in your area? I had never seen it until I moved to the southwest. Here, most residential panels are exterior meter/mains. They pretty much all have NM cables routed through large holes into the wall cavity, with no strain relief. It passes here as a matter of course, but I do not believe it is technically compliant.
__________________
I am a lawyer, but not your lawyer. And who cares anyways? We're here to talk construction. This is DIY advice, not legal advice.
mpoulton is offline   Reply With Quote
Old 02-28-2013, 04:56 PM   #12
Newbie
 
Join Date: Feb 2013
Posts: 26
Rewards Points: 25
Default

Question regarding new load center on cinder block wall.


I am in fact in the southwest: Tucson, AZ. It seems that almost all of the service boxes / load centers are on the outside of the house. I live in a newer 2007 track house and every house is set up this way. The house I am remodeling is from 1929 and like this too. Where I grew up in Southern California, it is this way also. I can't speak for other areas, but as you have noticed, it is common here.

Common doesn't make it right, but with virtually all of them this way, I'm assuming it is OK.

chris_b is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Load bearing wall removal question... Huggins90 Building & Construction 17 01-21-2013 11:07 AM
Mounting new load center to concrete block wall. speedster1 Electrical 77 09-09-2012 10:57 AM
Attaching patio cover to the top of cinder block wall robertwallace Building & Construction 7 07-10-2012 11:22 PM
Tying in a 2"x4" walled-booth with a cinder block wall johnofthemount Building & Construction 3 12-19-2009 03:51 PM
Creating passageway through cinder block wall ...? mark_p Building & Construction 7 09-14-2009 09:22 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.