Transfomer secondary tap rule

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anbm

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Two fused disconnect switches are fed out of a 75kVA, 3-PH, 480 pri. 208/120V sec. xfmr (I guess this is a tap rule?).
Each disconnect then feeds its own elec. panel. Will these two fused disconnect switches need to be
located within 10' from transformer ... or can they and the transformer be located in separate rooms?
Which NEC section address this situation? Thank you.
 
240.21(C) addresses transformer secondary conductors. Most likely you will use the not more than 10 feet or not more than 25 feet rules. 240.21(C)(2) and 240.21(C)(6) respectively.
 
anbm said:
Two fused disconnect switches are fed out of a 75kVA, 3-PH, 480 pri. 208/120V sec. xfmr (I guess this is a tap rule?).
Each disconnect then feeds its own elec. panel. Will these two fused disconnect switches need to be
located within 10' from transformer ... or can they and the transformer be located in separate rooms?
Which NEC section address this situation? Thank you.
Click to expand...
240.21(C) has six different situations that may apply.

most common situations that likely apply is either the ten foot rule or the 25 foot rule - each has specific requirements that must happen to allow their use. Transformer does not need to be within sight of the secondary disconnect(s) but total conductor length is restricted by certain conditions that go with each rule.

One of the conditions is for outdoors and has no conductor length restriction, but some of the content in OP suggests this is not outdoors so that probably won't apply.
 
victor.cherkashi said:
keep in mind, summary of secondary OCPD shall not exceed 125% (common mistakes based on my experience)

Sent from my ONEPLUS A6013 using Tapatalk
Click to expand...

Have a Code reference for that ??

(If the transformer has 125% PRIMARY protection I don't think the above is accurate)
 
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