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277 V Unit Heater #72374
11/27/06 09:59 PM
11/27/06 09:59 PM
highground  Offline OP
Joined: Nov 2004
Posts: 53
Chama, NM
I recently went on a service call for some high bays. While up in the lift I noticed the electric unit heaters had 277V nameplates but were installed in a building with 240V. No 277V is available.

(The motors are 277V rated as well)

The customer says they are about two years old?

Any thoughts as to potential problems?


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Re: 277 V Unit Heater #72375
11/27/06 10:11 PM
11/27/06 10:11 PM
Roger  Offline
Joined: May 2002
Posts: 1,716
Is there a chance that there are some Buck/Boost transformers somewhere?

We have done this before for this very situation.


Re: 277 V Unit Heater #72376
11/27/06 10:19 PM
11/27/06 10:19 PM
highground  Offline OP
Joined: Nov 2004
Posts: 53
Chama, NM
No Transformer Roger,

Small building, panel in sight of heaters.
I checked to see if there was one hiding.


Re: 277 V Unit Heater #72377
11/27/06 11:02 PM
11/27/06 11:02 PM
RODALCO  Offline
Joined: Dec 2005
Posts: 856
Titirangi, Akld, New Zealand
You won't get you maximum power output for heating.
240 volts is 86 % of 277 volts.
By V²/R you only get 75% of your heating capacity.

For the motors it depends if they have to start a heavy load or not.
If it is only to drive a fan i can't see any problems with it.

The product of rotation, excitation and flux produces electricty.
Re: 277 V Unit Heater #72378
11/27/06 11:31 PM
11/27/06 11:31 PM
JoeTestingEngr  Offline
Joined: Nov 2005
Posts: 791
Chicago, Il.
I doubt that you will have any problems but it wouldn't hurt to contact the mfg. to put your mind at ease.

Re: 277 V Unit Heater #72379
11/28/06 01:42 AM
11/28/06 01:42 AM
Lostazhell  Offline
Joined: Feb 2004
Posts: 1,431
Bakersfield, CA (Originally Or...
Only thing I can think of would be a conflict of something meant to run with a grounded phase vs. phase to phase... I'm not sure if this would be an issue in your case though...


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