Single Separately Derived System/2 Part

[paul hodge]

Double check me !!!

#1. When sizing the GEC for a separately derived system the GEC is sized in accordance with the primary conductors that supply the feed to the transformer. Correct? Based on table 250.66.

#2 Primary Conductor OCP on say for instance 30 kva transformer @ 480volt primary. Conductor OCP is 125% FLC.
As in 36.1 *125%= OCP

Primary conductors sized in accordance with this calulation.

I guess this really three part question.

 

[don_resqcapt19]

1) No...based on the size of the secondary conductors.
2) Primay OCPD at 125% is for primary only protection, you can go to 250% if you also have secondary protection
3) You must provide primary conductors that are protected at or below their ampacity
4) While 450.3 does not require secondary protection, the secondary conductors must be protected per 240.21(C).
Don