Resi Panels Main Breaker Phases Reversed

[Doc13067]

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]

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

 

[jaggedben]

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.

 

[Birken Vogt]

Siemens, Eaton BR, and QO I have confirmed inside the main breaker a cross happens

I don't believe this. Can you be more specific on what equipment?

 

[kwired]

I don't believe this. Can you be more specific on what equipment?

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.

 

[LarryFine]

It really doesn't matter with 1ph panels.

 

[infinity]

I don't believe this. Can you be more specific on what equipment?

It's true for the new 200 amp Eaton Panel I have in my home. When using it for MLO is A>A and B>B. For a main breaker is reverses A>B and B>A.

 

[Doc13067]

I don't believe this. Can you be more specific on what equipment?

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.

 

[Birken Vogt]

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

 

[infinity]

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

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]

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.

 

[Birken Vogt]

Well the panel I just posted that picture of was installed in the early 2000s so apparently not a real new thing.

 

[Doc13067]

Well the panel I just posted that picture of was installed in the early 2000s so apparently not a real new thing.

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.

 

[jaggedben]

I don't believe this. Can you be more specific on what equipment?

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.

 

[ptonsparky]

The guy doing a FOP check for the first on one of those is going to have a real WTH moment.

 

[hillbilly1]

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.

Square D I-Line, ABC on one side CBA on the other. But the breaker is actually marked with the correct phasing.

 

[jim dungar]

Square D I-Line, ABC on one side CBA on the other. But the breaker is actually marked with the correct phasing.

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.

 

[readydave8]

Maybe 10 years ago

A friend gave me some nearly new BR 200 amp main breakers

They all tested bad (continuity), I took one apart to see what was going on

And figured it out

 

[VirutalElectrician]

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.

 

[LarryFine]

And figured it out

Well, don't leave us hanging!