Transformer secondary fused disconnect

H

hhsting

Senior Member
Location
Glen bunie, md, us
Occupation
Junior plan reviewer
In order to comply with the transformer NEC 2017 Article 240.21(C), a fused disconnect 10 feet from 15 kVA 408V to 208/120V transformer secondary is supplied. The transformer is in ceiling.

My question is their maximum length for the transformer secondary fused disconnect or can it also be in ceiling as well? We are in NEC 2017
 
The answer would vary depending on details.
Generally speaking the switch would have to meet the 6'7" rule but there are exceptions for switches at utilization equipment, etc.
Also it's possible that the secondary 25' rule could apply or even longer for 240.92 situations.
 
hhsting said:
In order to comply with the transformer NEC 2017 Article 240.21(C), a fused disconnect 10 feet from 15 kVA 408V to 208/120V transformer secondary is supplied. The transformer is in ceiling.

My question is their maximum length for the transformer secondary fused disconnect or can it also be in ceiling as well? We are in NEC 2017
Click to expand...
While 240.21(C)(2) limits you to 10 feet of conductor between the transformer and the OCPD, 240.21(C)(6) permits 25' of conductor. It would be rare that you would be using a conductor small enough that you had to use the 10' limit in (C)(2).
 
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