Ungrounded delta system

Frank DuVal

Senior Member
Location
Fredericksburg, VA 21 Hours from Winged Horses wi
Occupation
Electrical Contractor, Electrical Engineer
I remember NYC had random incandescent lamps in their train terminals and tunnels.
And those where people could reach them were usually Left Hand thread!

I have a left hand thread bulb and pigtail. Hand it to someone who knows how to remove a bulb, and they have trouble. Hand it to a person not used to removing bulbs, and they unscrew it right away!;) Because they always try both directions!
 

Dsg319

Member
Location
West Virginia
Occupation
Journeyman Electrician
That would be a red herring. Customer owned general purpose transformers, with 480V primaries, are probably 99.99% delta wound.

You should check with your utility to see how their transformer is connected.
I’ll have to try and look at the pad mount utility transformer again but i couldn’t find any nameplate markings on it last time
 

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kwired

Electron manager
Location
NE Nebraska
I’ll have to try and look at the pad mount utility transformer again but i couldn’t find any nameplate markings on it last time
Our POCO transformers have no identifying information. Call them.
There is usually a nameplate, but with padmounts I have never seen one that wasn't inside the connections compartment so if locked you will not see it.
 

Jraef

Moderator
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Usually you can just call the utility and ask them what the secondary of the service transformer is, unless the end user owns the transformer (i.e. buys "bulk" power at the local transmission voltage).
 
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