Adding a sub panel Q UPDATE

[930dreamer]

I want a large dedicated circuit (100 amp +) in my shop to run a 30 hp 3 phase idler. I currently have a 125 amp panel that is fed off a 50 kva transformer, I think the transformer feeds three other shops.

I'll have to check on how many other shops might be connected to this transformer, its closest to my shop, but I'm furthest from the utility pole/street.

Does the transformer determine the size of sub panel I can add? Thanks!

 

[r_olson_06]

Re: Adding a sub panel Q

yes the transformer can determine the panel you install but so does the other loads attached to it. If you can figure out the other loads on the transformer and assuming that it is 480v to 208v transformer? I can do the math for you just send me a pm.

 

[930dreamer]

Re: Adding a sub panel Q

Sounds good, I'll be out of town for a while so when I get back I'll have the answers.

 

[930dreamer]

Re: Adding a sub panel Q

I haven't had a chance to talk to the property owner yet. Question, a sub-panel is fed off the main panels " main terminals", how do they connect? I went to look at some sub-panels and the box store person couldn't answer my question.

Does the main panel have a second set of lugs?

 

[Aceman]

Re: Adding a sub panel Q

You put a breaker in the main panel to feed the subpanel.

 

[930dreamer]

Re: Adding a sub panel Q

You put a breaker in the main panel to feed the subpanel.

Okay I'm tracking now.

 

[pauldeere]

Re: Adding a sub panel Q

Don't worry about the size of the transformer, that will become the responsibility of your electric company. They may have to upgrade the trans. to meet their customers demands. Ben There done that....

 

[930dreamer]

I installed a 100 amp breaker in the shop panel, feeding 6 ga wire, going into a 60 amp disconnect. I used a pony motor and fired up the 30 hp 3 phase idler. It's pulling 24.6 amps per lead at idle.

I'll still need to upgrade the wire, but it's a start.

Click for video

 

[wyliesdiesels]

Flamers: yes i know this old...

OP: Did u ever get this going? A few questions for you: its unclear from what you describe what your exact situation is. Does all 3 shops feed off of a 50kva PoCo owned transformer on a pole or is the 50kva a dry type transformer fed off the main service that supplies all 3 shops? If the former, then what is the size of the main service and do u just have a subpanel thats fed from it or do u have your own meter and service?