# Transformer wiring



## 480sparky (Sep 20, 2007)

What makes you think the 480-volt side is only for the primary? Trannys don't care which side it is being fed from. The only problem with supplying it with 208 and getting 480 off the H1/H2/H3 terminals is you won't have a neutral for 277v. If the lot lighting is strictly 480, then the tranny was probably installed for voltage drop purposes.

Oh, and welcome to the forum!


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## boyzrus (Aug 12, 2008)

Thanks, I understand that the tranny doesn't care and that one can use it either way. I'm bothered about the unbalanced load using H1 and H3. Yes it's three phase feeding two single phase 480 disconnects. When I connected to H2 and H3 instead of the previous, I got a more balanced load.(34/44/40)


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## 480sparky (Sep 20, 2007)

It could be one of two scenarios that come to mind:
1. The original installer didn't care about balancing the loads.
2. It was more balanced, but changes over the years have caused the numbers to start to vary.

If it's feeding two 2-pole 480 discos, you'll probably never get a better balance than what you've already gotten. If one disco is A-B and the second is B-C phases, then there's no A-C loads.


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## boyzrus (Aug 12, 2008)

Sparky,
Thanks for responding. As you will remember the tranny is a delta. The service is a wye. I believe there-in lies the problem. Both discos were originally wired to h1 and h3. The load balanced after I retapped to h2 and h3. The voltage from h1 to ground was 277 while the voltage from either h2 or h3 to ground was 480 and across the two was 480 as well. Thanks again!


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## brian john (Mar 11, 2007)

1. Did they run a neutral to the 208/120 side (which actually should be 208) no NEUTRAL with a wye primary.
2. With a short on one of the phases to ground (assume A phase) you should have to ground A-0 VAC, B-480 VAC, C- 480 VAC.
3. Possibly depending on the type of fixture you might have a short on one circuit and due to the type of load it may give you the 277.
4. OR In an ungrounded system the phases "FLOAT" above ground and the voltage measurement to ground will vary with load.
5. To have the current readings you stated you would need loads to be single phase 480 with B phase utilized more (if that makes since) A-B, B-C.

And lastly not he best transformer for the application in my opinion.

Where in VA?


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## boyzrus (Aug 12, 2008)

Brian,
no neutral, three phase 120/208 feed panel through three phase delta 480/120-208 tranny to single phase 480 discos. South central Virginia


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