The local utility company is going to install 500KVA transformer, secondary voltage is 480/277V, can I connect one set of 500kcmil conductors to feed a 400A service rated panel with main breaker to the transformer lugs, and another set of conductors 3/0 conductors to the utility transformer secondary lugs to feed a 200A panel with main breaker? Length of each set of conductors is 20', transformer will be a pad mount, and the two panels will be 3R rated and installed outdoors, next to the transformer.
Utility Transformer Connections
- Thread starter hochwire
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
What does the utility say? It is fine code wise, but some utilities will not permit that.
Iron_Ben
Senior Member
- Location
- Lancaster, PA
We (poco) would have been fine with that. 99% of the time we used CT's on the padmount transformer low side bushings for metering. We would supply 6, 8, or 12 (sometimes more) position connectors on the bushings. Where those low side 500 (or whatever) MCM cables went, well, we typically didn't look too closely.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Out of curiosity, what do you see as a potential issue with the utility?
- Location
- Massachusetts
Anything from the number of conductors to the type of wire. It is there space and you never know what wacky issues they may have.
I think Don was just suggesting it is wise to check with them before going to far.
- Location
- Illinois
- Occupation
- retired electrician
Exactly. How you make that installation is up to the utility.
There are some that will not let you run directly from their transformer to multiple service disconnects. They make you run to a tap or splice box and then to multiple service disconnects.
The only reason I mentioned metering is because POCO will not want to put in two meters for one service. As mentioned, POCO typically put Ct's on the low side bushings to meter... but not always... so you'll want to make certain this is how your POCO wants to meter your service.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Interesting, that is ridiculous, never ran across that one
- Location
- Massachusetts
They do things like that so transformer replacement is fast and easy. That is the same reason many utilities around me will not allow any metering equipment in or on their transformer.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I don't see how sets of service conductors are any different than conductors in parallel in terms of transformer swap out ( probably preaching to the choir here).
It's a bummer when they don't do padmount metering, makes it so much cheaper and easier. I believe all the national grid subsidiaries do it.
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