3 phase 277/480 volt rated panel

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verhndy

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I went on a call for a furniture install . They spec a 3 pole 20 amp circuit 110 volt for a furniture feed thru box The closest 3 phase panel installed by someone is 277/480 volt panel fed from 120/208 3 phase panel . other than being expensive and stupid . Is this a code violation .
 
Why would you think it's stupid? If the service is 120/208 and they needed 277/480 it makes sense and was probably cheaper than bringing a new service to the facility

Roger
 
No and it is often done intentionally to get a higher aic rating on the panel. This standard 277 volt CB is also rated at 120 volts and 65K.65KAIC Circuit Breaker.jpg
 
Oops, I misunderstood, I see the OP is saying they used a 277/480 volt panel for 120/208 volts and I agree with Rob

Roger
 
infinity said:
No and it is often done intentionally to get a higher aic rating on the panel. This standard 277 volt CB is also rated at 120 volts and 65K.View attachment 2558190
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I have heard of this, but I am unclear why it is done. You can purchase regular 120/240 breakers that are rated 65k. Are the 480/277 breakers cheaper? Based on some quick and dirty research it doesn't appear so. I am most familiar with Siemens products and a bqd is there typical 480 / 277 breaker, it is rated 14k at 480/277 and 65k at 240. Now a Siemens B320HH is their 240V breaker rated 65K. A quick Google showed a price of $140. A quick Google for the BQD shows a price pretty much the same. Now just to be complete, if you really aren't messing around and want/need 100k at 240 you could go with a NGB (600v) breaker.....
 
petersonra said:
Might have been something they had laying around and wanted to use up. Or it could have been that it was easier to get for the required AIC rating.
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277/480 breakers are probably more common than the HH 240 breakers, but if its a factory order doesnt seem like it would matter.

So I actually just got a Siemens quote for a 250A 120/208 PB with 62 poles of breakers. They made a mistake and first quoted it with the "H" 22KAIC 240V breakers. I then got the revised quote with standard 10k. FWIW, it was $3.78 more per pole for the 22KAIc breakers.
 
electrofelon said:
277/480 breakers are probably more common than the HH 240 breakers, but if its a factory order doesnt seem like it would matter.

So I actually just got a Siemens quote for a 250A 120/208 PB with 62 poles of breakers. They made a mistake and first quoted it with the "H" 22KAIC 240V breakers. I then got the revised quote with standard 10k. FWIW, it was $3.78 more per pole for the 22KAIc breakers.
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I am not sure how true it is but I was told once by someone who might actually know that there is no real difference between the lesser rated breakers as far as AIC goes other than the marking. Apparently there is a sweet spot where you can get more interrupting rating without having to change the design. I don't know how high up that goes though.
 
petersonra said:
I am not sure how true it is but I was told once by someone who might actually know that there is no real difference between the lesser rated breakers as far as AIC goes other than the marking. Apparently there is a sweet spot where you can get more interrupting rating without having to change the design. I don't know how high up that goes though.
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Yeah I have heard that too. Sometime I will get a 120, 120H, and 120HH breaker and take them apart and see if I can find any difference......
 
Someone may of wanted the higher AIC rating of the 480/277V, & 277V, breakers in the 480/277V panelboard.
 
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