Cutler Hammer panels

jaggedben

Senior Member
...
The NEC settled on 120% of the busbar rating, specifically. BTW, the door stickers (enclosure rating) on these 200A panels say "Maximum mains 225A".
Then in my lingo it was a 225A panelboard to begin with.

All I'm saying is that I need a label on the item that says 225A. I don't have time to gamble on whether the AHJ will accept a letter from the manufacturer that may or may not apply to some older panel.
 

pv_n00b

Senior Member
Location
CA, USA
The NEC settled on 120% of the busbar rating, specifically. BTW, the door stickers (enclosure rating) on these 200A panels say "Maximum mains 225A".
That's interesting on its own. What do they mean saying a 200A panelboard is "Maximum mains 225A"? That even if there is a 200A main CB that the feeder has to be protected for 225A max? Now I have to go talk to a panelboard manufacturer. Is that the CH panelboard?
 

Adamjamma

Senior Member
That's interesting on its own. What do they mean saying a 200A panelboard is "Maximum mains 225A"? That even if there is a 200A main CB that the feeder has to be protected for 225A max? Now I have to go talk to a panelboard manufacturer. Is that the CH panelboard?
If you are feeding a main breaker of 60 amps from a 60 amp breaker in another panel, you don’t size the wire for the 225 amps that could be red if an idiot changes the main breaker, do you?
Nor do you size the feed breaker for the panel rating but for the load needed at the panel, which is what you set the main breaker at.
or am I reading the feeder rules wrong?
 

jaggedben

Senior Member
That's interesting on its own. What do they mean saying a 200A panelboard is "Maximum mains 225A"? That even if there is a 200A main CB that the feeder has to be protected for 225A max? Now I have to go talk to a panelboard manufacturer. Is that the CH panelboard?
'Max mains rating' or 'mains rating' is something I see all the time, and I've always taken it to be the rating of the panelboard. It says absolutely nothing about a feeder rating, you may of course feed a panelboard at less than its rating. And a main breaker, is there is one, protects it.

My question for ggunn now is, why did you ever think they were 200A panels if they say 'max mains rating 225A' on them? Because you were looking at a catalog instead of the panel label? Because the panel label was missing?
 

kwired

Electron manager
Location
NE Nebraska
Not familiar enough with Eaton to comment on them.

Square D QO loadcenter covers are somewhat universal, meaning one cover can fit more than one loadcenter. Rating of the panelboard is always on the label inside the cabinet and not a label on the cover for them.

If you want 225 amp bus with 200 amp main breaker, one way to assure this is to purchase "convertible mains" 225 amp mail lug panel and convert it to a 200 amp main breaker panel. Will cost more than a 200 amp with main breaker already installed and very possibly still has same bus installed.
 

pv_n00b

Senior Member
Location
CA, USA
If you are feeding a main breaker of 60 amps from a 60 amp breaker in another panel, you don’t size the wire for the 225 amps that could be red if an idiot changes the main breaker, do you?
Nor do you size the feed breaker for the panel rating but for the load needed at the panel, which is what you set the main breaker at.
or am I reading the feeder rules wrong?
Panelboards are sized to the load based on the load calculations in NEC chapter 2 and the main or feeder breakers are sized to protect the panelboards, not the loads. None of this prevents installing a 200A panelboard for a 10A load and feeding it with a 10A rated feeder. But that would be kind of dumb, if someone wanted a 200A panelboard but only had a 10A load today I would provision the panelboard for its full 200A rating and then more loads could be added later, or I would recommend they install a smaller panelboard.
 

GoldDigger

Moderator
Staff member
One notable exception (for service, not feeders) is LADWP. Last I heard they require a 200A service for a 200A panelboard, regardless of how small the main breaker is. This makes life difficult for Solar PV installers at times.

Sent from my XT1585 using Tapatalk
 

kwired

Electron manager
Location
NE Nebraska
Panelboards are sized to the load based on the load calculations in NEC chapter 2 and the main or feeder breakers are sized to protect the panelboards, not the loads. None of this prevents installing a 200A panelboard for a 10A load and feeding it with a 10A rated feeder. But that would be kind of dumb, if someone wanted a 200A panelboard but only had a 10A load today I would provision the panelboard for its full 200A rating and then more loads could be added later, or I would recommend they install a smaller panelboard.
Is somewhat common to see 100 or 125 amp panelboard supplied by a lesser feeder, because lesser panelboard isn't always something readily available. Even 225 amp MLO panelboard supplied by 150, 175 or 200 amp feeder is fairly common for same reason.
 

pv_n00b

Senior Member
Location
CA, USA
I've been asking around the upper echelons of our fine industry and it seems that no one has a really strong opinion on this issue and most feel that it's okay to use the higher busbar rating. I would definitely check with the AHJ if I were going to do this as the rework if it went bad would be a problem.

Personally, I would stick with the panelboard rating but since I do little work that is not using switchboards for service entrances it has not been an issue I have had to put a lot of thought into. If I were doing this every day I might feel differently.
 
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pv_n00b

Senior Member
Location
CA, USA
So interesting how those two areas have had issues with this and the rest of the country hasn't :roll: :rant:
LA and Palo Alto have been known problem areas out here for years. There are some PV contractors who just won't install in Palo Alto. It's actually sad because Palo Alto has a municipal utility that is really PV friendly but the building department has consistently held PV to unusually strict interpretations of the NEC requirements.
The LA building department and municipal utility are just plain wacky. There was a time when they would not allow any non-isolated inverters to be used because they said they inject DC into their system.
 
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