# 3-phase power question WRT theater lighting

**URL:** <https://boards.straightdope.com/t/3-phase-power-question-wrt-theater-lighting/966656>\
**Category:** Factual Questions\
**Created:** [June 23, 2022, 12:27am UTC](https://boards.straightdope.com/t/3-phase-power-question-wrt-theater-lighting/966656 "2022-06-23T00:27:03Z")\
**Posts on this page:** 2\
**Page:** 2

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**Author:** ![Snipe70e](https://avatars.discourse-cdn.com/v4/letter/s/51bf81/32.png) [@Snipe70e](https://boards.straightdope.com/u/Snipe70e)\
**Post date:** [June 24, 2022, 4:00am UTC](https://boards.straightdope.com/t/3-phase-power-question-wrt-theater-lighting/966656/21 "2022-06-24T04:00:23Z")

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> [@Crafter\_Man](#):
>
> Nitpick: if it’s a wye configuration, then yea… it’s very common to get single phase 120 VAC by connecting between any one of the three legs and neutral. Getting a ground-referenced single phase from delta is a bit more rare. You can get 120 VAC with a delta “high leg,” and you can get 240 VAC using a corner ground. But as mentioned, it’s much more common with a wye.

I did not want to go into the wye-delta thing. I think is was around 1970 that they stopped wiring buildings Delta. I have worked in buildings that had phase lights to detect ground faults. One building I thought it was funny. The city moved and replaced the utility transformers and the secondary of the new 480/277 transformer was wound wye. But the phase lights were left in place.

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**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\
**Post date:** [July 1, 2022, 6:03pm UTC](https://boards.straightdope.com/t/3-phase-power-question-wrt-theater-lighting/966656/22 "2022-07-01T18:03:25Z")

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> [@Tim\_T-Bonham.net](#):
>
> Theatre lights are all single-phase, 108 or 120 volts nominal (less actually, since they are run on dimmers most of the time). About the only theatre lights that _might_ be more are large follow spots, but they are usually at most 240V single-phase. And not likely to be used in a high school theatre.
> 
> Also, most theatre lighting is not incandescent any more.

I’ll see you LEDs and raise a xenon. Speaking of which, anyone need a 4 kVA xenon power supply?

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