Transformer Secondary Conductors

Don’t let secondary rules get you wound up
Find more articles about Transformers

Similar to feeder taps, covered in the last issue, transformer secondary conductors can be every bit as confusing. Let's take a closer look at 240.21(C) to help clear up any misconceptions. Basic rules As with feeder taps, you can't use the rule provided in 240.4(B) for any transformer secondary conductor. Normally, you can use the next highest overcurrent protective device (OCPD) above the ampacity

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MPHarold
on Feb 7, 2013

I'm still a little confused on 240.21(C)(1). In the case of the 3-phase delta-wye transformer secondary conductors, does the OCPD have to be at the transformer, the point where the conductors receive their supply, or are you allowed to use 240.21(C)(2) 10' rule or 240.21(C)(3) 25' rule?

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