Required or not required that is the question

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Blue_42

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Clark County NV
I have mcc with c/b feeds VFD. VFD is getting ISO trans in front of it. Going to pipe to and from mcc into adjacent room to ISO trans (480 delta to 480 wye) location using 2" rigid. VFD is in sight of mcc, ISO trans is not. What requirements if any for disconnect? Either on primary or secondary? I hear different interpretations of article 240 & 450.

I am looking for interpretations/opinions/explanations of the codes....thanks
 
don_resqcapt19

don_resqcapt19

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Location
Illinois
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retired electrician
Blue_42 said:
I have mcc with c/b feeds VFD. VFD is getting ISO trans in front of it. Going to pipe to and from mcc into adjacent room to ISO trans (480 delta to 480 wye) location using 2" rigid. VFD is in sight of mcc, ISO trans is not. What requirements if any for disconnect? Either on primary or secondary? I hear different interpretations of article 240 & 450.

I am looking for interpretations/opinions/explanations of the codes....thanks
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The location of the primary disconnect must be posted at the transformer, (450.14 in the 2011 code) it is not required to be within sight from the transformer. The secondary conductors will need to be protected per one of the rules in 240.21(C). This may require the secondary conductor OCPD to be located within sight of the transformer, but not because it has to be within sight, rather because of the maximum permitted length of the secondary conductor between the transformer and the OCPD.
 
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