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Resi Panels Main Breaker Phases Reversed

Doc13067

Doc13067

Senior Member
Location
Bucks County/Philadelphia, PA USA
So i discovered this a few years back but Siemens, Eaton BR, and QO I have confirmed inside the main breaker a cross happens so that what you think is Phase A on the main breaker line side lug is actually Phase B when it comes out the load side of the breaker. Therefore the left bus is actually connected to the right service or feeder conductor and vice versa. Does anyone know why this is and does it cause a problem? And if we are trying to put Phase A on the black conductor and Phase B on the red conductor but the standard is that black should be on the left and red should be on the right, well that is just impossible. Are 3 phase panels phased the way they “should” be?
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
If you happen to be trying to balance a three phase system this is something you may need to take into consideration.

If all you have is a single phase system it really doesn't matter. Your imbalance is going to be on one side or the other , and the phase relationship is same either way where with three phase you may get a rotational difference if you switch things around
 
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jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
For songle phase it only matters if you are putting CTs somewhere. If you are just installing the service you can either not bother marking L2 red, or test your main breaker and land L1 and L2 so that the panel comes out according to convention. There's no code rule and nobody really cares. I suppose the worst is to get the wires marked inconsistently. Better not to mark red on the supply side at all.
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
Birken Vogt said:
I don't believe this. Can you be more specific on what equipment?
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The main breaker in certain load centers, mostly those with a horizontal operating handle but with input/output out of top and bottom. One that plugs or bolts on to the same bus section as outgoing branches are not the ones being talked about here.

Main breakers in commercial panelboards typically not part of what is the topic here.
 
Doc13067

Doc13067

Senior Member
Location
Bucks County/Philadelphia, PA USA
Birken Vogt said:
I don't believe this. Can you be more specific on what equipment?
Click to expand...
Siemens PN Series 100 amp or 200 amp. Square D QO 100 amp or 200 amp, Eaton BR 200 amp. Do you have access to any of these panels not yet installed? I noticed it years ago. All you have to do is turn the main breaker on and do a continuity test from the left line side lug to the left load side tab that has the bolt with a nut that connects the left load side of the breaker to the left bus bar. Do that and you will not get a reading. Then test from the left line side lug to the right bus bar and you will get a reading. Then you will realize that main breaker right line is A on the bus and main breaker left side is B on the bus. Perhaps this is only with single phase panels.
 
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Birken Vogt

Senior Member
Location
Grass Valley, Ca
Well I'll be. I have a SqD on the shelf but not sure I care enough to take it down and unbox it, now that I just looked at a photo of one I was working on the other day, attached. I just never looked that close or cared I guess.

Should have know better than to doubt the regulars on here
 

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infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Birken Vogt said:
Well I'll be. I have a SqD on the shelf but not sure I care enough to take it down and unbox it, now that I just looked at a photo of one I was working on the other day, attached. I just never looked that close or cared I guess.

Should have know better than to doubt the regulars on here
Click to expand...
I was dumbfounded when I saw this on the new service panel I installed in my house. There was a thread not too long ago where on brand of 3Ø panels had A-B-C reversed from left to the right sides.
 
Doc13067

Doc13067

Senior Member
Location
Bucks County/Philadelphia, PA USA
Birken Vogt said:
Well the panel I just posted that picture of was installed in the early 2000s so apparently not a real new thing.
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Yeah it’s probably been like that forever but it takes a loser like me who buys panels and sits on the floor with screwdrivers and a meter dissecting them to understand how every piece is connected. The label graphics are so easy to miss because when you’re looking there you’re usually looking for a torque spec or something and just gloss over whatever you’re not looking for.
 
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jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Birken Vogt said:
I don't believe this. Can you be more specific on what equipment?
Click to expand...
Definitely true for Eaton CSR breakers. Here's another panel label where they actually show it.

Edit: Now that I look, I notice that they cross the factory wiring so that if you land black and red on left and right at the meter, it comes out the way you'd like at the panel bus. But this is a meter main, the convertible panels aren't like that.
 

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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
infinity said:
I was dumbfounded when I saw this on the new service panel I installed in my house. There was a thread not too long ago where on brand of 3Ø panels had A-B-C reversed from left to the right sides.
Click to expand...
Square D I-Line, ABC on one side CBA on the other. But the breaker is actually marked with the correct phasing.
 
J

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
hillbilly1 said:
Square D I-Line, ABC on one side CBA on the other. But the breaker is actually marked with the correct phasing.
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You used to be able to order I-line breakers with a CBA suffix, which put the breakers in a more typical top to bottom arrangement. Except for some government projects I don't know of anyone that order them, because as you said the breaker label was always correct.
 
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VirutalElectrician

Senior Member
Location
Mpls, MN
Occupation
Sparky - Trying to be retired
DPDT swiches also have a similar reversal. When the lever is pointing one way, it's actually closing the contacts on the opposite side of the switch. It makes logical sense with a DPDT switch, as the base of the switch is what is determining which contacts are opened/closed.

Now I'm going to have to find an old main breaker and cut it open to see what's actually going on inside there.
 
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