transformer secondary protection

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benmin

benmin

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Location
Maine
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Master Electrician
480/277 to 208/120 45kva transformer. Primary protected by 70A breaker. Secondary is under 10' long supplying a panel. Can the panel be Main lug or does it need to be a main breaker?
 
benmin said:
480/277 to 208/120 45kva transformer. Primary protected by 70A breaker. Secondary is under 10' long supplying a panel. Can the panel be Main lug or does it need to be a main breaker?
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The transformer doesn't care. However the panelboard will require a main device, somewhere between it and the transformer (408.36).
 
jim dungar said:
The transformer doesn't care. However the panelboard will require a main device, somewhere between it and the transformer (408.36).
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Ahh I see it now. 408.36 sends you to 240.21(c)(1) in this case. I was eying 240.21(c)(2) and should have noticed the informational note. Thanks
 
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