400 amp busbar BUT 300 amp line rating

A

Anvilsbeme

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Location
New Mexico
Occupation
apprentice
We have a grid tied PV system backfeeding a main panel in which we have an inspector giving us fits concerning the 120% rule. We have a Schneider Electric panel (model #QONQ42MS300) which is a 400 amp panel that can be fitted with a 300 or 400 amp main breaker. The UL sticker lists the line rating but not the busbar rating. I called Schneider and they said the busbar rating is not stated on the sticker because both options (whether a 300 or 400 amp main breaker) are built with a 400 amp busbar.

The inspector insists on using the line rating in his 120% calculations. Schneider sent me an email stating the busbar rating but he won't accept this because I might have "doctored" up the numbers. When Schneider emailed him directly, he did not accept their email because it now needed to be sent by someone stating their first and last name, engineering title, with a physical signature, and then scanned and emailed.

Any suggestions on how to prove to him this panel has a 400 amp busbar?

Thanks in advance for any help!
 
Anvilsbeme said:
We have a grid tied PV system backfeeding a main panel in which we have an inspector giving us fits concerning the 120% rule. We have a Schneider Electric panel (model #QONQ42MS300) which is a 400 amp panel that can be fitted with a 300 or 400 amp main breaker. The UL sticker lists the line rating but not the busbar rating. I called Schneider and they said the busbar rating is not stated on the sticker because both options (whether a 300 or 400 amp main breaker) are built with a 400 amp busbar.

The inspector insists on using the line rating in his 120% calculations. Schneider sent me an email stating the busbar rating but he won't accept this because I might have "doctored" up the numbers. When Schneider emailed him directly, he did not accept their email because it now needed to be sent by someone stating their first and last name, engineering title, with a physical signature, and then scanned and emailed.

Any suggestions on how to prove to him this panel has a 400 amp busbar?

Thanks in advance for any help!
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It is very frustrating when manufacturers do not label basic critical information on the product or in the datasheet or catalog. Schneider's explanation that it is not stated on the sticker because both options use the same busbar is actually a reason TO label it on the sticker. Makes it hard on us. Maybe if you looked at the actual UL documentation it might be there?
 
This annoys me as another clueless inspector thing. He apparently doesnt have any experience with panelboards. I am not very familiar with Sq D panelboards (I know siemens pretty well), but cant you download the catalog which should break down the part numbers and all the ratings? (I just tried to download it but it keeps failing for some reason).

I also agree with Ken that its super annoying they dont put this information on there. Come on, get with the program UL.
 
Anvilsbeme said:
We have a grid tied PV system backfeeding a main panel in which we have an inspector giving us fits concerning the 120% rule. We have a Schneider Electric panel (model #QONQ42MS300) which is a 400 amp panel that can be fitted with a 300 or 400 amp main breaker. The UL sticker lists the line rating but not the busbar rating. I called Schneider and they said the busbar rating is not stated on the sticker because both options (whether a 300 or 400 amp main breaker) are built with a 400 amp busbar.

The inspector insists on using the line rating in his 120% calculations. Schneider sent me an email stating the busbar rating but he won't accept this because I might have "doctored" up the numbers. When Schneider emailed him directly, he did not accept their email because it now needed to be sent by someone stating their first and last name, engineering title, with a physical signature, and then scanned and emailed.

Any suggestions on how to prove to him this panel has a 400 amp busbar?

Thanks in advance for any help!
Click to expand...

Is there someone in the state where you can over his head. You are an apprentice so what does your boss say.... he should be doing the arguing
 
solarken said:
It is very frustrating when manufacturers do not label basic critical information on the product or in the datasheet or catalog. Schneider's explanation that it is not stated on the sticker because both options use the same busbar is actually a reason TO label it on the sticker. Makes it hard on us. Maybe if you looked at the actual UL documentation it might be there?
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Good idea! I'll try to find the UL documentation.
 
Let me see if I understand the issue. The panel busbar is rated 400 amps but the line rating is 300 amps. What is meant by line rating
 
Dennis Alwon said:
Let me see if I understand the issue. The panel busbar is rated 400 amps but the line rating is 300 amps. What is meant by line rating
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The bus bar is reported to be 400A, the main breaker is 300A, the panel label doesn't say anything about 400A, and the inspector is being (excessive? ) about the 400A documentation.
 
You might be able to find a small label on the bus bar portion of the assembly, as that is what is used for the main lug only version of that panelboard.

Have you asked your supply house for any assistance?
All of the typical online literature will probably not have what you need.
 
electrofelon said:
Have you tried looking in the square d panel board catalog and seeing if that has the information you need?
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Great idea! I just did and it shows the only bus bar options for the NQ panelboards are 100, 225, 250, 400, and 600 amp. Logic would say that since my QONQ42MS300 panel is line rated at 300, then its bus bar is 400 because if it was 250A, then the panel would be rated at 250A. Maybe this will convince the inspector??? See screenshot attached.
 

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jim dungar said:
You might be able to find a small label on the bus bar portion of the assembly, as that is what is used for the main lug only version of that panelboard.

Have you asked your supply house for any assistance?
All of the typical online literature will probably not have what you need.
Click to expand...
Thanks, will try to locate one. We did ask the supply house but they couldn't provide definitive proof; they said this information is known and shouldn't be questioned...the same as the 200A panels have a 225A bus.
 
Anvilsbeme said:
Great idea! I just did and it shows the only bus bar options for the NQ panelboards are 100, 225, 250, 400, and 600 amp. Logic would say that since my QONQ42MS300 panel is line rated at 300, then its bus bar is 400 because if it was 250A, then the panel would be rated at 250A. Maybe this will convince the inspector??? See screenshot attached.
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Although theoretically possible, seems highly unlikely a panel with a 300A MB would have a 250 A bus, so yes conclude must be 400A
 
electrofelon said:
Although theoretically possible, seems highly unlikely a panel with a 300A MB would have a 250 A bus, so yes conclude must be 400A
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Schneider's technical support has confirmed to me in an email that both of their QONQ42MS300 and QONQ42MS400 panels (300A and 400A main breaker, respectively) are the identical boxes, covers, and bus bars (400A), the only difference is which main breaker it is fitted with. The problem is the inspector won't accept their email to me because I could "doctor it up" and make it say whatever I want. He won't accept the same email directly to him because he wants it on letterhead, full name, engineering title, with wet signature.
 
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