Question about residential main breakers - Electrician Talk - Professional Electrical Contractors Forum
CLICK HERE AND JOIN OUR COMMUNITY TODAY, IT'S FREE!
Go Back   Electrician Talk - Professional Electrical Contractors Forum > Electrical Forum > General Electrical Discussion


Like Tree26Likes
Reply
 
Thread Tools Display Modes
Old 10-09-2017, 07:16 PM   #1
Senior Member
 
carryyourbooks's Avatar
 
Join Date: Jan 2010
Location: KATY, TX
Posts: 1,627
Rewards Points: 1,292
Default Question about residential main breakers

Today, a topic come up about residential main breakers, specifically 100a and 125a side-mounted main breakers. I was told that the space right across from a main breaker should not be used due to heat. I know some panels are made so that you cannot use that space directly across from them because there is not bus bar there, but what about those that are? We always install new panels with a main at the top, but what about existing panels? Are they in some sort of violation if they have other branch breakers across from the main?
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
carryyourbooks is offline   Reply With Quote
Join Contractor Talk

Join the #1 Electrician Forum Today - It's Totally Free!

ElectricianTalk.com - Are you a Professional Electrical Contractor? If so we invite you to join our community and see what it has to offer. Our site is specifically designed for you and it's the leading place for electricians to meet online. No homeowners asking DIY questions. Just fellow tradesmen who enjoy talking about their business, their trade, and anything else that comes up. No matter what your specialty is you'll find that ElectricianTalk.com is a great community to join. Best of all it's totally free!

Join ElectricianTalk.com - Click Here JOIN FOR FREE


Warning: The topics covered on this site include activities in which there exists the potential for serious injury or death. ElectricianTalk.com DOES NOT guarantee the accuracy or completeness of any information contained on this site. Always use proper safety precaution and reference reliable outside sources before attempting any construction or remodeling task!

Sponsored Links
Advertisement
 
Old 10-09-2017, 07:25 PM   #2
Mensa Player
 
HackWork's Avatar
 
Join Date: Oct 2009
Location: -
Posts: 33,243
Rewards Points: 1,653
Default

Nope.

If you can physically install the breaker there and it doesn't say not to install one on the sticker on the panel cover, you are good to go.

The sticker will tell you if a main can be installed, which breaker to use, and which hold-down kit to use.

The older Siemens hold-down kit was small and allowed a breaker to be installed across from it. The newer hold-down kit takes up that space, not allowing a breaker to be installed.
__________________
I'm trying to think, but nothing happens.
HackWork is online now   Reply With Quote
The Following User Says Thank You to HackWork For This Useful Post:
carryyourbooks (10-10-2017)
Old 10-09-2017, 07:29 PM   #3
Mensa Player
 
HackWork's Avatar
 
Join Date: Oct 2009
Location: -
Posts: 33,243
Rewards Points: 1,653
Default

Here is an example. This is a 12 space panel that they factory install a 100a main. You can see in the picture that you can use all 10 remaining spaces, including the 2 across from the main: http://www.homedepot.com/p/Eaton-100...SRNV/100568618
__________________
I'm trying to think, but nothing happens.
HackWork is online now   Reply With Quote
The Following User Says Thank You to HackWork For This Useful Post:
carryyourbooks (10-10-2017)
Sponsored Links
Advertisement
 
Old 10-09-2017, 10:00 PM   #4
Senior Member
 
220/221's Avatar
 
Join Date: Sep 2007
Location: Phoenix, AZ
Posts: 7,614
Rewards Points: 4,000
Default

No matter what the instructions say, logic says to give it some breathing room if you can.

I have seen probably one hundred AC breakers burn the bus along with the breakers and bus next to it so I got into the habit of, when possible, leaving some space and not putting big loads next to to each other.
220/221 is offline   Reply With Quote
Old 10-09-2017, 10:08 PM   #5
Mensa Player
 
HackWork's Avatar
 
Join Date: Oct 2009
Location: -
Posts: 33,243
Rewards Points: 1,653
Default

Quote:
Originally Posted by 220/221 View Post
No matter what the instructions say, logic says to give it some breathing room if you can.

I have seen probably one hundred AC breakers burn the bus along with the breakers and bus next to it so I got into the habit of, when possible, leaving some space and not putting big loads next to to each other.
That's because you geniuses live in the scorching hot desert and put your panels outside in the sun and heat.

Those of us who live in normal places with panels inside never saw 100 AC breakers burn the bus along with the breakers next to it.

Logic says if breakers need breathing room they would be spaced apart.
jbfan and MTW like this.
__________________
I'm trying to think, but nothing happens.
HackWork is online now   Reply With Quote
The Following User Says Thank You to HackWork For This Useful Post:
strawburner (10-13-2017)
Old 10-10-2017, 01:51 AM   #6
Senior Member
 
carryyourbooks's Avatar
 
Join Date: Jan 2010
Location: KATY, TX
Posts: 1,627
Rewards Points: 1,292
Default

Thanks, guys!
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
carryyourbooks is offline   Reply With Quote
Old 10-10-2017, 05:33 AM   #7
Retired Account
 
Join Date: Mar 2011
Location: the Green Mountain state
Posts: 39,722
Rewards Points: 14,650
Default

Quote:
Originally Posted by carryyourbooks View Post
Today, a topic come up about residential main breakers, specifically 100a and 125a side-mounted main breakers. I was told that the space right across from a main breaker should not be used due to heat. I know some panels are made so that you cannot use that space directly across from them because there is not bus bar there, but what about those that are? We always install new panels with a main at the top, but what about existing panels? Are they in some sort of violation if they have other branch breakers across from the main?

The topic resurfaces every now/ then

Your answer is in the listing

Specifically, the 'bus' of any given panel is good for XX amps

~CS~
splatz likes this.
chicken steve is offline   Reply With Quote
Old 10-10-2017, 06:58 PM   #8
Chief Flunky
 
Join Date: Oct 2017
Location: Carolinas
Posts: 965
Rewards Points: 328
Default

Circuit breakers should NOT overheat. The residential ones almost exclusively use a thermal trip element which works on heat so it SHOULD get hot if there is a fault. Otherwise if your panel is hot, its a high resistance connection that is an impending failure and needs to be replaced. That's why progressive companies use infrared cameras to check their panels.

The biggest design/installation error is under sizing the AIC in industrial panels...basically putting it on too big of a transformer for what it is rated for. This is rarely a problem in residential conditions. Instead I tend to see double tapped mains, common neutrals, putting way too many wires under a terminal, all kinds of wire but violations, improper ground terminations or maybe no ground bar at all, never filled out the panel schedule or 6 entries that all say "receipts" or "lights", and no grounding or plastic bushings, two screws with all kinds of things other than a single NM under them, and things stripped waaay too far back.

And 125A panels? That's OK for 1970s stuff but not now. Not sure you can even buy them that small. When you can buy a prepopulated lighting panel rated 150 or 200 A with 24 breakers already installed for about $300 even a SqD and not a throwaway India made Siemens or GE (made in the same plant!), why buy the unpopulated panel and individual breakers except to soak the customer on parts?


Sent from my Galaxy Tab 2 using Tapatalk
paulengr is offline   Reply With Quote
Old 10-10-2017, 07:03 PM   #9
Mensa Player
 
HackWork's Avatar
 
Join Date: Oct 2009
Location: -
Posts: 33,243
Rewards Points: 1,653
Default

Quote:
Originally Posted by paulengr View Post
Circuit breakers should NOT overheat. The residential ones almost exclusively use a thermal trip element which works on heat so it SHOULD get hot if there is a fault. Otherwise if your panel is hot, its a high resistance connection that is an impending failure and needs to be replaced. That's why progressive companies use infrared cameras to check their panels.

The biggest design/installation error is under sizing the AIC in industrial panels...basically putting it on too big of a transformer for what it is rated for. This is rarely a problem in residential conditions. Instead I tend to see double tapped mains, common neutrals, putting way too many wires under a terminal, all kinds of wire but violations, improper ground terminations or maybe no ground bar at all, never filled out the panel schedule or 6 entries that all say "receipts" or "lights", and no grounding or plastic bushings, two screws with all kinds of things other than a single NM under them, and things stripped waaay too far back.

And 125A panels? That's OK for 1970s stuff but not now. Not sure you can even buy them that small. When you can buy a prepopulated lighting panel rated 150 or 200 A with 24 breakers already installed for about $300 even a SqD and not a throwaway India made Siemens or GE (made in the same plant!), why buy the unpopulated panel and individual breakers except to soak the customer on parts?


Sent from my Galaxy Tab 2 using Tapatalk
I was with you for a while, but then you went full ret*rd. You never go full reta*d.
TheLivingBubba likes this.
__________________
I'm trying to think, but nothing happens.
HackWork is online now   Reply With Quote
Old 10-10-2017, 07:26 PM   #10
Magic Smoke Remover
 
Join Date: Aug 2011
Location: Oklahoma
Posts: 1,004
Rewards Points: 1,966
Default

Quote:
Originally Posted by HackWork View Post
That's because you geniuses live in the scorching hot desert and put your panels outside in the sun and heat.

Those of us who live in normal places with panels inside never saw 100 AC breakers burn the bus along with the breakers next to it.

Logic says if breakers need breathing room they would be spaced apart.
I've seen BR melt down in a conditioned space with A/Cs grouped, but not 100 of them.
matt1124 is offline   Reply With Quote
Old 10-10-2017, 07:36 PM   #11
HTTR
 
Jack Legg's Avatar
 
Join Date: Mar 2014
Location: east coast
Posts: 528
Rewards Points: 804
Default

its in the listing. If there is a limit it will state something like this:
Question about residential main breakers-user310441_pic20626_1476740634.jpg
Jack Legg is offline   Reply With Quote
The Following User Says Thank You to Jack Legg For This Useful Post:
telsa (10-12-2017)
Old 10-10-2017, 07:39 PM   #12
Mensa Player
 
HackWork's Avatar
 
Join Date: Oct 2009
Location: -
Posts: 33,243
Rewards Points: 1,653
Default

Quote:
Originally Posted by matt1124 View Post
I've seen BR melt down in a conditioned space with A/Cs grouped, but not 100 of them.
There must have been some other issue.

If this was a thing, the manufacturer would specify no large breakers next to each other or to leave an empty space between them. Or the NRTL that listed the panel would make them require that.
__________________
I'm trying to think, but nothing happens.
HackWork is online now   Reply With Quote
Old 10-10-2017, 07:56 PM   #13
MTW
Senior Member
 
MTW's Avatar
 
Join Date: Aug 2013
Location: Northeast USA
Posts: 14,588
Rewards Points: 8,332
Default

Quote:
Originally Posted by paulengr View Post
Circuit breakers should NOT overheat. The residential ones almost exclusively use a thermal trip element which works on heat so it SHOULD get hot if there is a fault. Otherwise if your panel is hot, its a high resistance connection that is an impending failure and needs to be replaced. That's why progressive companies use infrared cameras to check their panels.

The biggest design/installation error is under sizing the AIC in industrial panels...basically putting it on too big of a transformer for what it is rated for. This is rarely a problem in residential conditions. Instead I tend to see double tapped mains, common neutrals, putting way too many wires under a terminal, all kinds of wire but violations, improper ground terminations or maybe no ground bar at all, never filled out the panel schedule or 6 entries that all say "receipts" or "lights", and no grounding or plastic bushings, two screws with all kinds of things other than a single NM under them, and things stripped waaay too far back.

And 125A panels? That's OK for 1970s stuff but not now. Not sure you can even buy them that small. When you can buy a prepopulated lighting panel rated 150 or 200 A with 24 breakers already installed for about $300 even a SqD and not a throwaway India made Siemens or GE (made in the same plant!), why buy the unpopulated panel and individual breakers except to soak the customer on parts?
Are you Telsa's alter ego?
A Little Short likes this.
MTW is offline   Reply With Quote
Old 10-10-2017, 08:58 PM   #14
Registered Member
 
Join Date: Feb 2008
Location: Alabama
Posts: 11,885
Rewards Points: 1,360
Default

The bus stabs have a rating like posted above. I've seen some say 110, some are 125, and some are 140 amps per stab. So, for example, if the stabs are rated at 110 amps, then putting two 60 amp breakers across from each other would be a no no. It stands to reason that this would apply to the bus the main is attached to as well.
eddy current and splatz like this.
RePhase277 is offline   Reply With Quote
Old 10-12-2017, 03:56 PM   #15
Senior Member
 
220/221's Avatar
 
Join Date: Sep 2007
Location: Phoenix, AZ
Posts: 7,614
Rewards Points: 4,000
Default

Quote:
Originally Posted by HackWork View Post
That's because you geniuses live in the scorching hot desert and put your panels outside in the sun and heat.
I was born in Phoenix and if I moved, I doubt it would ne to Jersey lol. Talk to me at the end of January when you are freezing your nuts off and I'm still in shorts and short sleeves.

The panel location is irrelevant because 99.9% of them work just fine.

But AC's do work hard here.
220/221 is offline   Reply With Quote
Old 10-12-2017, 05:34 PM   #16
Chief Flunky
 
Join Date: Oct 2017
Location: Carolinas
Posts: 965
Rewards Points: 328
Default

Quote:
Originally Posted by RePhase277 View Post
The bus stabs have a rating like posted above. I've seen some say 110, some are 125, and some are 140 amps per stab. So, for example, if the stabs are rated at 110 amps, then putting two 60 amp breakers across from each other would be a no no. It stands to reason that this would apply to the bus the main is attached to as well.


This doesn't make any sense. The bus is protected by the main, not the branch circuit breakers. You could have a 10 slot panel rated 100 A and 10 15 A breakers. It can theoretically be loaded to 150 A but that would then trip the main. The branch breakers protect the branch circuits. This almost never happens in practice due to diversity (loads are not 100%) and granted unless they are 100% rated they trip at 80% (12 A) etc., etc., but the idea that branch circuit breaker sizes and positions are limited by the bus size does not pass the smell test.

This is far different from vertical vs. horizontal ampacity in MCC but that's different because there isn't a separate overcurrent device for the vertical bus sections. In that circumstance and some feeder cases it is legal and required to protect upstream bus with downstream protection but that's not the case in a panelboard.


Sent from my iPhone using Tapatalk
paulengr is offline   Reply With Quote
Old 10-12-2017, 06:06 PM   #17
Mensa Player
 
HackWork's Avatar
 
Join Date: Oct 2009
Location: -
Posts: 33,243
Rewards Points: 1,653
Default

Quote:
Originally Posted by paulengr View Post
This doesn't make any sense.
It makes perfect sense. You should think twice, or 3 times, before question MrPhase.

Quote:
The bus is protected by the main,
The bus, but not the stabs.

Quote:
not the branch circuit breakers.
The branch circuit breakers protect the stabs.

Here is an example of the listing of a Murray panel:

Quote:
SUM OF MH-T BREAKER RATING IS NOT TO EXCEED 110 AMPS PER BRANCH CIRCUIT BUS STAB.
http://www.homedepot.com/catalog/pdf...8846ea993e.pdf

As you can see, you can't put a 90A and 60A breaker on the same stab (next to each other) since the stabs are only rated at 110A.

That is what MrPhase was speaking about.
__________________
I'm trying to think, but nothing happens.
HackWork is online now   Reply With Quote
The Following User Says Thank You to HackWork For This Useful Post:
MechanicalDVR (10-12-2017)
Old 10-12-2017, 08:06 PM   #18
Senior Member
 
brian john's Avatar
 
Join Date: Mar 2007
Location: Gilbert's Corner VA
Posts: 29,908
Rewards Points: 1,588
Default

Quote:
Originally Posted by paulengr View Post
Circuit breakers should NOT overheat. The residential ones almost exclusively use a thermal trip element which works on heat so it SHOULD get hot if there is a fault. Otherwise if your panel is hot, its a high resistance connection that is an impending failure and needs to be replaced. That's why progressive companies use infrared cameras to check their panels.
A Molded case circuit breaker trips on a fault from magnetic trip NOOT THERMAL, thermal tripping is from an sustained overload.

Quote:

And 125A panels? That's OK for 1970s stuff but not now. Not sure you can even buy them that small. When you can buy a prepopulated lighting panel rated 150 or 200 A with 24 breakers already installed for about $300 even a SqD and not a throwaway India made Siemens or GE (made in the same plant!), why buy the unpopulated panel and individual breakers except to soak the customer on parts?


Sent from my Galaxy Tab 2 using Tapatalk
Check the load on a residential panel and except for houses with electric heat most residential services are way over sized.

Quote:
The biggest design/installation error is under sizing the AIC in industrial panels...basically putting it on too big of a transformer for what it is rated for. T.
The size of the transformer is not this issue in regards to AIC, It is the available fault current the utility can provide in their distribution system. Two identical transformers can have different available fault currents based on many variables in the distribution system.
HackWork and TheLivingBubba like this.
__________________
Ah, but I was so much older then, I'm younger than that now

Last edited by brian john; 10-12-2017 at 08:11 PM.
brian john is offline   Reply With Quote
Old 10-12-2017, 08:14 PM   #19
Senior Member
 
brian john's Avatar
 
Join Date: Mar 2007
Location: Gilbert's Corner VA
Posts: 29,908
Rewards Points: 1,588
Default

Quote:
Originally Posted by matt1124 View Post
I've seen BR melt down in a conditioned space with A/Cs grouped, but not 100 of them.
Bad CB or high resistance connection to the bus.
MechanicalDVR and HackWork like this.
__________________
Ah, but I was so much older then, I'm younger than that now
brian john is offline   Reply With Quote
Old 10-12-2017, 08:35 PM   #20
Registered Member
 
Join Date: Feb 2008
Location: Alabama
Posts: 11,885
Rewards Points: 1,360
Default

I'm going to send a strongly worded email to the major panel manufacturers telling that that Paul from "The Carolinas" doesn't like the way their breakers smell. Strongly worded. Strongly.
matt1124 likes this.
RePhase277 is offline   Reply With Quote
Reply

Thread Tools
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
Odd question about residential 120V smoke detectors Bzzzzzt General Electrical Discussion 20 08-26-2017 10:46 PM
Double panel design question. JohnJ65 Services and Service Equipment 23 07-07-2017 08:19 PM
Locking residential main breaker in the 'ON' position. Sparkysquared Canadian Electrical Forum 16 09-28-2016 05:42 PM
ontario smoke/co/strobe for residential rules question lohirise Canadian Electrical Forum 11 04-17-2016 10:56 PM
Residential main feed voltage fluctuation stackvortex General Electrical Discussion 27 03-14-2016 08:53 PM


All times are GMT -4. The time now is 10:20 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.1
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Our Pro Sites Network
ContractorTalk.com | DrywallTalk.com | HVACSite.com | PaintTalk.com | PlumbingZone.com | RoofingTalk.com