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You are permitted to lug it down, to the minimum value in NEC 430 Part II. The general rule is the motor circuit conductors must be at least 125% of the motor fla from Table 430.250. There are some exceptions, but that is the general rule. In this case 240 amps is fla, so 240x1.25 = 300 amps...

I'm struggling to understand the transformer configurations. One side is ungrounded wye, which is, and what is the other side connection? "Check the voltage between XO and XO (Neutrals)." If the high side is wye, be sure it is grounded. Ungrounded wye high sides can create unusual secondary...

It's been a long time since I worked on transformer protection, but they have an (I**2)t withstand rating. The use of the CL fuse is to limit the energy pass through. I've seen pole mount transformers that exploded, showering oil everywhere, due to too much energy. CL fuse use is very...

kevinopp It's not just the load on the secondary, delta, side of your transformers that cause the fuses to blow. If there is an unbalance on the 2400/4160 side, a grounded high side will allow the transformer to attempt to balance the high side imbalance. If you have a grounded high side...

Is there a requirement in the NESC or elsewhere that requires utilities to protect against overcurrents? I'm not aware of one. Jim T

I'm not sure that your premise is true. I worked for electric utilities for 20 years before moving into consulting, and we NEVER sized transformers for peak loading. In fact we tolerated slight overloads as long as voltages were OK. Jim T

If you are governed by the NEC, refer to 310.6 In general, shielding is now required over 2000 volts, however there are some exceptions. Jim T

I am interested in other views of utility transformer pole grounding. NESC Rule 94B indicates that pole plates and butt wraps are not to be the only grounding electrode at transformer poles. I rarely see more than a butt wrap on transformer poles around here, particularly in areas served by...