# Breaker Placement on Bus Bars



## caseyelectric (Oct 19, 2008)

Never thought bout that but I dont think it would have any effect. its an open buss that has no restrictions in other words its not feeding other breakers before it feeds the one at the bottom or the opposite


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## sparky970 (Mar 19, 2008)

Signalservice said:


> Does anyone know if there is Code about placing circuit breakers in a panel? Personally, I have usually put heavy load breakers farthest away from the main, with the hydraulic comparision that if a water hydrant upstream from your house is opened, you will have far less water pressure, then if someone opened a fire hydrant downstream from your house. The heavy load (usually 240 volt) positioned downstream would seem to affect the upstream circuits less. Following the same logic, power sensitive circuits: media racks and the like, I like to put close to the main. It probably doesnt matter: Hopefully the manufacturers have sized the buss bars the keep the voltage (pressure) constant thru out the buss. I also have noticed on older G.E. panels that the opportunity for using mini breakers exists on the buss bars farthest away from the main lug or breaker, not close to the main terminals.


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## Mr Rewire (Jan 15, 2011)

You are the 'supervising" electrician?


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## T Healy (Aug 27, 2011)

Signalservice said:


> Does anyone know if there is Code about placing circuit breakers in a panel? Personally, I have usually put heavy load breakers farthest away from the main, with the hydraulic comparision that if a water hydrant upstream from your house is opened, you will have far less water pressure, then if someone opened a fire hydrant downstream from your house. The heavy load (usually 240 volt) positioned downstream would seem to affect the upstream circuits less. Following the same logic, power sensitive circuits: media racks and the like, I like to put close to the main. It probably doesnt matter: Hopefully the manufacturers have sized the buss bars the keep the voltage (pressure) constant thru out the buss. I also have noticed on older G.E. panels that the opportunity for using mini breakers exists on the buss bars farthest away from the main lug or breaker, not close to the main terminals.


 You're correct it does not matter where you place the breakers. Balance between phases is what you should try to achieve.


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## RGH (Sep 12, 2011)

186,000 miles/per sec...do ya think it matters.....balance the load thats the big thing...


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## Mr Rewire (Jan 15, 2011)

The EE will have the loads balanced on the prints just follow them.


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## Signalservice (Sep 7, 2011)

Mr Rewire said:


> You are the 'supervising" electrician?


 well, Ive got 30 years in all aspects of the trade..Have seen numerous warped buss barrs, mostly millbank and wadsworth "modular hook-ups" in apartment buidings. So, it is something I think about. In elementary electrical theory, the analogy of volts as water pressure and current as the size of water pipe is accepted practice that I have seen in more then one book. My code book tells me for copper buss a square inch at 1/4" thick is good for 1000 amps. If I have 2 50 amp 2 pole breakers right at the top of my buss near the mains, gripping the vertical bus with 1/4"" square clip points, and my buss is 3/4" wide with 1/8 inch vertical blades for the breaker grippers to come into contact with, I think there is going to be some heat build-up there, right on the bus at the main, won't that impact the rest of the breakers downstream from the heat build-up?


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## erics37 (May 7, 2009)

Signalservice said:


> well, Ive got 30 years in all aspects of the trade..Have seen numerous warped buss barrs, mostly millbank and wadsworth "modular hook-ups" in apartment buidings. So, it is something I think about. In elementary electrical theory, the analogy of volts as water pressure and current as the size of water pipe is accepted practice that I have seen in more then one book. My code book tells me for copper buss a square inch at 1/4" thick is good for 1000 amps. If I have 2 50 amp 2 pole breakers right at the top of my buss near the mains, gripping the vertical bus with 1/4"" square clip points, and my buss is 3/4" wide with 1/8 inch vertical blades for the breaker grippers to come into contact with, I think there is going to be some heat build-up there, right on the bus at the main, won't that impact the rest of the breakers downstream from the heat build-up?


....

Electrical theory says that current will take all paths available, inversely proportional to impedance. Your whole bus bar is rated for whatever it's rated for. If you put a 100 amp load at the top or the bottom, it doesn't matter, it will draw 100 amps either way. The other loads in between will still draw whatever they draw too.

Now it might be worth taking into consideration putting lots of high-current loads immediately adjacent to one another, because they DO generate some amount of heat based on the current flow, but that doesn't have anything to do with your bus bar running out of electrons for the subsequent breakers.


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## niteshift (Nov 21, 2007)

Signalservice said:


> well, Ive got 30 years in all aspects of the trade..Have seen numerous warped buss barrs, mostly millbank and wadsworth "modular hook-ups" in apartment buidings. So, it is something I think about. In elementary electrical theory, the analogy of volts as water pressure and current as the size of water pipe is accepted practice that I have seen in more then one book. My code book tells me for copper buss a square inch at 1/4" thick is good for 1000 amps. If I have 2 50 amp 2 pole breakers right at the top of my buss near the mains, gripping the vertical bus with 1/4"" square clip points, and my buss is 3/4" wide with 1/8 inch vertical blades for the breaker grippers to come into contact with, I think there is going to be some heat build-up there, right on the bus at the main, won't that impact the rest of the breakers downstream from the heat build-up?


 
As stated above. 

Load on breaker or a loose connection, or foreign material effects it, and/or bussbar at attachment points.

Think only time I know of that it effected breakers below, above or adjacent was with a catastrophic failure.


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## Mr Rewire (Jan 15, 2011)

Signalservice said:


> well, Ive got 30 years in all aspects of the trade..Have seen numerous warped buss barrs, mostly millbank and wadsworth "modular hook-ups" in apartment buidings. So, it is something I think about. In elementary electrical theory, the analogy of volts as water pressure and current as the size of water pipe is accepted practice that I have seen in more then one book. My code book tells me for copper buss a square inch at 1/4" thick is good for 1000 amps. If I have 2 50 amp 2 pole breakers right at the top of my buss near the mains, gripping the vertical bus with 1/4"" square clip points, and my buss is 3/4" wide with 1/8 inch vertical blades for the breaker grippers to come into contact with, I think there is going to be some heat build-up there, right on the bus at the main, won't that impact the rest of the breakers downstream from the heat build-up?


Try reading the code nook before you get to 31 years


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## McClary’s Electrical (Feb 21, 2009)

I like to put the larger loads up top to dissipate the heat quicker rather than if placed on the bottom, the heat produced by a 60 amp breaker hsa to travel through all the other breakers on top of it.


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## Signalservice (Sep 7, 2011)

I also have installed a couple of 400 amp single phase main panels,with a factory installed 200 amp breaker for a sub panel preinstalled: at the bottom of the panel farthest away from the main.


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## McClary’s Electrical (Feb 21, 2009)

Mr Rewire said:


> Try reading the code nook before you get to 31 years


 

This is why everybody enjoyed your time off.


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## brian john (Mar 11, 2007)

RGH said:


> 186,000 miles/per sec...do ya think it matters.....balance the load that's the big thing...


 
There is voltage drop in every conductor, in panel bus most likely insignificant in the overall scheme of things.

But if you really wanted to apply logic, I would think the heavier loads should be near the MCB or MLO. Less voltage drop, then you could argue the smaller loads were effected by this VD. I say screw the smaller loads as they are insignificant PIA's.:blink:



> I like to put the larger loads up top to dissipate the heat quicker rather than if placed on the bottom, the heat produced by a 60 amp breaker hsa to travel through all the other breakers on top of it.


As much as it pains me to say, there is some validity to this, we see this quite often when performing IR's. Had a case were two 200 Amp Circuit breakers both feeding UPS running at about 60% load the top CB (thermal magnetic) was nusisance tripping, yet FOP showed both CBs had the close to the same VD. IR indicated the TOP CB had thermal issues


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## brian john (Mar 11, 2007)

Signalservice said:


> I also have installed a couple of 400 amp single phase main panels,with a factory installed 200 amp breaker for a sub panel preinstalled: at the bottom of the panel farthest away from the main.


 
Only because that fits their design nothing to do with anything else, I would bet.


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## brian john (Mar 11, 2007)

Mr Rewire said:


> The EE will have the loads balanced on the prints just follow them.


 
I doubt that.


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## JmanAllen (Aug 3, 2011)

Mr Rewire said:


> The EE will have the loads balanced on the prints just follow them.


That shows your a service guy all prints I've seen say the EC is responsible for making sure the load is balanced


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## RGH (Sep 12, 2011)

I admit that when I lay out a panel if there is no spec for circuit locations I place them at the top aswell....but then are we not putting more heat nearer the the MBC ?...I think it just opens up work space in the panel aswell..larger conductors up top and outta the way...if they are entering panel topside as usual..overall if panel is spec'd correctly per load demands/load calc's i really don't see any issues..just watch your balance...IMHO


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## Meadow (Jan 14, 2011)

It does not matter where you place them, however I have noticed AFCIs perform better or a least Ive heard when spaced apart.


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## oldtimer (Jun 10, 2010)

meadow said:


> It does not matter where you place them, however I have noticed AFCIs perform better or a least Ive heard when spaced apart.



I M O, breakers in a panel, should never really get hot, if they are sized right for the load. 

Warm maybe!

As long as all connections are tight, and breaker fits tight on bus, there should not be a problem with heat.

Just My Opinion!


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## Stab&Shoot (Aug 23, 2011)

Mr Rewire said:


> Try reading the code nook before you get to 31 years


What's wrong with you?! You have no respect for your peers. Your opinions are worthless and your input is NOT spot on!


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## brian john (Mar 11, 2007)

oldtimer said:


> I M O, breakers in a panel, should never really get hot, if they are sized right for the load.
> 
> Warm maybe!
> 
> ...


 
I think you will find you start getting more than a few circuit breakers running at 80% and are truly continuous, you will see heat. That IMO over the long term will be determential to the CBs.


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## Stab&Shoot (Aug 23, 2011)

JmanAllen said:


> That shows your a service guy all prints I've seen say the EC is responsible for making sure the load is balanced


Yeah he's probably good at servicing 'knobs and tubes' only!


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