480/277V panelboard instead of 208/120V

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highlegdelta

Member
Location
US
We have used 480Y/277 volt panels for 208Y/120 volt circuits when the engineer wanted 65 KA interrupting rating circuit breakers. GE Type TEY CB's are rated for 65 KA @120 volts.
We have done the same thing. It was cheaper and faster to get a 480v panel with the AIC ratings needed than a 208v panel with equivalent ratings


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GoldDigger

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Location
Placerville, CA, USA
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Retired PV System Designer
Warning: unless the combination you choose is specifically series rated by the manufacturer with the main panel breakers, the breakers in the subpanel will still need to meet the higher AIC!
 

highlegdelta

Member
Location
US
Interesting. And that was cheaper than regular 240 breakers series rated to a a main breaker eh? I wouldn't have thought so.
It was a few years ago so I don't remember specifics. Series rating wasn't an option thanks to some FPE gear so we had to fully rate. It likely would have been cheaper to have it ordered and built but it was a last minute thing. We had to go with stock panels and breakers. We also didn't fill half the panel with spares.
 

kwired

Electron manager
Location
NE Nebraska
I am speculating, but I imagine the gear was ordered with breakers. To do otherwise on a factory gear order is a good way to spend a ton of extra money.
NQ and NF panels are both usually purchased as a package deal, if you want best cost. They may not be all that much difference in cost either when purchased as a complete package vs as individual items.

You can get higher interrupt ratings on the QO but may be faster/easier/less cost, or a little bit of all those,to go with standard rating NF then it is to go with high interrupt rating NQ.
 
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