XFMR question

[ptonsparky]

...however, how many times do you see a transformer in a building without a qualifying water pipe or building steel nearby?

i have a dairy barn we are working on that has multiple transformers nowhere close to qualifying building steel or a waterline. 500 to 1300 ft or more. The secondaries are ungrounded 120v. 480v primary. Loads are up to 500' from the transformers with a green wire but no secondary bond. What a can of worms.

 

[kwired]

i have a dairy barn we are working on that has multiple transformers nowhere close to qualifying building steel or a waterline. 500 to 1300 ft or more. The secondaries are ungrounded 120v. 480v primary. Loads are up to 500' from the transformers with a green wire but no secondary bond. What a can of worms.

Unless they are around those applications people don't realize livestock and farming operations these days are seldom small ma and pa operations anymore, they are small industrial plants with 480/277 volt services with maybe even 1000 amps plus capacity in some instances, and a lot of somewhat complex controls and other automation. Just a generation or two ago most dairy farms still had a 60 or 100 amp 120/240 single phase supply to the main milking area, but they only milked 50 cows or less instead of 500, 1000 or even more.

 

[ActionDave]

i have a dairy barn we are working on that has multiple transformers nowhere close to qualifying building steel or a waterline. 500 to 1300 ft or more. The secondaries are ungrounded 120v. 480v primary. Loads are up to 500' from the transformers with a green wire but no secondary bond. What a can of worms.

Life on the farm is kinda laid back,
ain't too much an 'ol country boy can't hack,
it's early out of bed and early in the sack,
Thank God I'm a country boy!

 

[acrwc10]

There is some back and forth between recent code cycles whether or not an EGC can also be a GEC. I've never been in a situation where I had to do it so I never gave it a lot of concentration.

I would rather run a wire back to the service than drive a ground rod.

It is done quite often in PV systems. In this situation the service and water main are quite a ways away, so a ground rod is the answer. I just can't think of a reason not to allow the larger EGC to be used as a GEC for the new transformer.