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Re: 220V Service line

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On 2026-02-28 10:55, UFO wrote:
> 
> Setting up a new shop, but will need a 220 line for servicing some high 
> power equipment.
> 
> This transformer sits on the floor near the breaker panels:
> 
> General Electric 9T23B3872
> https://www.rexelusa.com/p/193724/abb/transformer-dry-type-30kva-480-delta-primary-208y-120v-secondary-/783173004920/9t23b3872 
> 
> 
> Specs say it steps down 480 to 120 and 208.
> 
> Is 208 gonna work for 220? Never heard that voltage mentioned in my 
> travels.
> 
> The 120V wall outlets read about 123V on the DMM, sort of high than 
> where I was previously.
> 

Hopefully you have a real electrician coming to do the 
installation--480V mains power is no joke whatsoever.

208 is the nominal voltage across two phases of a three-phase feed.
|240*sin(120 degrees)| = 207.85.

I once had an actual electrician mistakenly connect 208 to a 240V 
single-phase load (a brand-new, fancy lamp-pumped Nd:YAG laser).  This 
effectively browned out the internal switching converter, resulting in 
overcurrent large enough to cause the (underrated) fuseholder to catch fire.

Exciting times in the lab. :(

Cheers

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

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220V Service line "UFO" <techforce@nospam.gmx.com> - 2026-02-28 10:55 -0500
  Re: 220V Service line Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-03-02 15:16 -0500

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