Available Fault Current From This Open Delta ?

[Joethemechanic]

Been waiting weeks for the POCO to get back to me about my available fault current so I can shop for a main breaker.

Here are some pictures of the open delta on the pole. My service lateral is at least 100 feet.




I know it's got to be calculated right and if I had a bucket truck I'd go up and get the transformer specs and the gauge of the service drop and do the calculations. But these are small pole pigs, how much available fault current could there be? 22K? 25K? More?

 

[don_resqcapt19]

Usually you can see the KVA from the ground and make a guess based on typical impedance for pole transformers.

 

[Joethemechanic]

Usually you can see the KVA from the ground and make a guess based on typical impedance for pole transformers.

Yeah I couldn't see it good. I can't find my damn binoculars either. I've got to go get a new pair. They only feed my 225ish amp service and a little single phase service that is lucky if it's even 150 amps at the garage across the street. They can't be very big.

If I was 19 or 20 again I'd go up that pole with gaffs and look

 

[tjdilly]

No way to guess with certainty, but those look like either 15kva's or 25kva's to me.

 

[Joethemechanic]

This is what I'm thinking of using

QDL32225 | Schneider Electric Circuit Breaker​

A 25KVA pole mounted transformer would be maybe max 10k bolted fault current at the secondaries

The Square D QDL32225 is 25k AIC

If I'm wrong here let me know. I'm used to dealing with much larger pad mount transformers and transformers fed by a customer owned medium voltage bus. I don't know much about pole pigs