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Sizing a disconnect for a Unit Heater #68395
08/05/06 06:27 PM
08/05/06 06:27 PM
C
Cinner  Offline OP
Member
Joined: Dec 2004
Posts: 78
Kelowna, B.C., Canada
A 3000 watt unit heater is to be installed in a storage room...it has a fan built in... but is does not have a HP rating...3 phase 208 volts...what size disconnect is required?

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Re: Sizing a disconnect for a Unit Heater #68396
08/05/06 07:10 PM
08/05/06 07:10 PM
Tom  Offline
Member
Joined: Jan 2001
Posts: 1,044
Shinnston, WV USA
The motor load for a unit heater this small is unlikey to exceed 1/8th HP. If you were to use a standard safety switch, a 3 pole 30 amp switch would do the trick.

An alternative would be a 3 pole switch such as a Hubbell HBL7810BW. This type of switch is made by others, but that is the only catalog # I have handy. This switch will cost about as much as a safety switch and will probably need to be ordered.

You may not need a disconnect at the heater if the circuit breaker complies with 424.19(B)(1)


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Re: Sizing a disconnect for a Unit Heater #68397
08/09/06 10:47 PM
08/09/06 10:47 PM
R
RobbieD  Offline
Member
Joined: Feb 2003
Posts: 231
Canada
15 Amp three phase breaker

[This message has been edited by RobbieD (edited 08-09-2006).]


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