Space Heater w/ Auxiliary Box (240V @ 120V)

[HotPotato]

Hello All,

I received a bid from a vendor that states they are including "Space Heater w/ Auxiliary Box (240V @ 120V)". This space heater will be inside of an industrial 30HP TECO 3600 RPM TEFC 460/3/60 Class 1 Div 2 Groups C & D motor.

Could anybody please help me understand EXACTLY what this vendor is offering with regards to "240V @ 120V"? I need 120 V space heaters. Is "240V @ 120V" just a fancy way of stating the space heater can accept two voltage power sources?

 

[davidbeach]

Possibly 240V heaters connected at 120V. Heater puts out 25% of rated wattage at a much lower surface temperature and lasts much longer than if connected at 240V. Very commonly done in switchgear.

 

[GroovyGuy]

I agree with David. It is very common to spec a heater to be rated 240V, but operated at 120V (or 208V). This reduces the surface temperature significantly, which is likely important in your Div 2 motor. I trust that the motor OEM also provides a T-Code on the motor NP as well.

BTW, if the above is true in your circumstance, do not connect the motor heater to a 240V supply. This will seriously exceed the T-Code rating for the motor.

Of course it is possible that the motor OEM has given you the option of a 240V or 120V connection, but I think this is very unlikely on such a small motor.
How many leads in the heater T-box?. If only 2, then our assupmtion must be correct, n'est pas?
Why not ask the motor OEM?
GG

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