Distribution Transformers and Power Transformers

Is this a test?

Well I don't know If its relevant or not but my complaint is they give people to small of transformer for our homes!

I have a 120/240 volt 200 Amp service but only a 15 KVA transformer. To me 240 volts at 200 amps service capacity should have a 40 KVA transformer. (NEC 80% of maximum breaker VA capacity rating rule.)

My service voltage dims whenever my 15 hp air compressor starts.

I have seen this on almost everyones power service around here. My friends shop has all electric heat and draws 45 KW but he has only a 30 KVA transformer for his 120/240 volt 400 Amp service. When all heaters are running he gets a very big voltage drop as well.

The utility company says the transformers can handle extended overloads but still how much overload do we get to have before they burn out? 50% for an hour? 100% for half an hour?

All I have ever been told is if it burns up they will give me a bigger one. So why not give me the right sized one to start with and have far fewer burn out?

Page 1 of the NEC "this code does not apply to electric utilities . . ." There is a reason for that.

For example, NEC sizes a fuse to protect circuit wiring. Utilities on the other hand size a fuse to protect the transformer. The fuse will go before the xformer. There are a lot of other practical reasons that the NEC is not written to govern utilities, though they use the same parameters when they apply.

Most utilities in the US are regulated by a governing body, Public utility commission etc, and they have service requirements in place. Somewhere in their service agreement there is language as to the range of voltage they are allowed to supply, and that is the issue you need to bring to them. If they are regularly supplying too low of a voltage due to the loads, they will probably have to upgrade the transformer.

To the OP, most transformer complaints are about blown fuses/outages, and about how they look. Many people would prefer to have them not visible, such as inside, or underground. CJM

This sort of thing is probably commercially-sensitive information embraced by the marketing agenda, and as such is unlikely to be in the public domain.