Identifying bus bar rating for Square D QO load center

[dave68]

I cannot find the serial number on a Square D QO load panel. The label on the inside indicates main lugs kit QOL225, and main breaker type QOM2. The main breaker installed is 200 Amp. Does the main lug rating indicate bus bar rating? I cannot find bus bar rating on any of the labels.

Thank you for any input

 

[kwired]

Look for a label on the panel interior, that will give you the catalog number of what that interior was when it was manufactured, even if the main had been swapped or converted to/from main lugs only. The label on the cabinet is only general information for the cabinet and to any interior they make that fits the same cabinet.

I just looked at a panel I have in the shop, the label on that interior is right next to where the main lugs of a main breaker would be located if it had a main breaker installed.

This won't tell you if you have a 200 or 225 amp bus but will give you the original cat no which you may be able to research that to find out.

 

[jim dungar]

Your label clearly says that if you were going to install a main lugs kit, that you would use one rated 225A. Why do you think your main bussing is lower than this amount?

It also says a main breaker would have to be a QOM2 breaker, which is available up to 225A. If there are no restrictions listed on the label, why do you think your main bus would not be rated for the maximum?

 

[kwired]

Your label clearly says that if you were going to install a main lugs kit, that you would use one rated 225A. Why do you think your main bussing is lower than this amount?

It also says a main breaker would have to be a QOM2 breaker, which is available up to 225A. If there are no restrictions listed on the label, why do you think your main bus would not be rated for the maximum?

Look at the catalog, here is one example that doesn't leave us all that clear of what bus ratings actually are for panels that accept QOM2 mains or the 225 amp lug kit.

For indoor single phase main lug panel they list in the catalog 150, 200, and 225 amps mains ratings. All have the same main lugs or will accept any QOM2 breaker which goes up to 225 amps. There is only one panel in the 225 amp category - it is a 42 space panel. There is also a 42 space panel in the 200 amp category. I have to assume these do not have the same bus. I would also assume if you have a panel that was factory assembled with a 200 amp main breaker it likely does not have a 225 amp bus.

JMO and seems logical that is what they would do.

 

[jim dungar]

...a 200 amp main breaker it likely does not have a 225 amp bus.

JMO and seems logical that is what they would do.

Logical would be to build one single busbar and use it in all installations, the cost of manufacturing and tracking multiple parts is not worth the difference in cross section area between 100A and 225A. After all, the majority of the bus assembly dimensions are fixed due to breaker connections and interior mounting.

There are other fators such as lug size that determine the actual panel rating.

 

[kwired]

Logical would be to build one single busbar and use it in all installations, the cost of manufacturing and tracking multiple parts is not worth the difference in cross section area between 100A and 225A. After all, the majority of the bus assembly dimensions are fixed due to breaker connections and interior mounting.

There are other fators such as lug size that determine the actual panel rating.

I agree with your logic, yet they have a 200 amp main lug panel and a 225 amp main lug panel - both 42 circuits, both use the same cabinet - about has to be a difference in the bus to get two different ratings. Same thing goes with the 150 and 200 amp 30 circuit main lug panels.

The panels that accept the QOM1 main breaker all likely have 125 amp bus from what I can tell though.

 

[electrofelon]

Logical would be to build one single busbar and use it in all installations, the cost of manufacturing and tracking multiple parts is not worth the difference in cross section area between 100A and 225A. After all, the majority of the bus assembly dimensions are fixed due to breaker connections and interior mounting.

There are other factors such as lug size that determine the actual panel rating.

I took over a partially done job and I needed a 200 amp MLO panelboard because we had that breaker available in the Siemens P4 main panalboard. There was a stack of Siemens 125 MLO's there but damn, no 250's. There was a 250 already installed as a house panel fed from a 100 amp breaker. Is it worth swapping them out, I begin to debate? Closer inspection with dial calipers yielded that both interiors were exactly the same, only the dead fronts were different - one said "250 amp" the other sad "125 amp". So I swapped the dead fronts and called it a day.

I remember having a discussion about the square D stuff a while back and, if I recall correctly, there was evidence that "150 Amp" and above all have a 225 amp buss.