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#68395 - 08/05/06 03:27 PM Sizing a disconnect for a Unit Heater
Cinner Offline

Registered: 12/01/04
Posts: 77
Loc: Kelowna, B.C., Canada
A 3000 watt unit heater is to be installed in a storage 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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#68396 - 08/05/06 04:10 PM Re: Sizing a disconnect for a Unit Heater
Tom Offline

Registered: 01/01/01
Posts: 1069
Loc: 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)
Few things are harder to put up with than the annoyance of a good example.

#68397 - 08/09/06 07:47 PM Re: Sizing a disconnect for a Unit Heater
RobbieD Offline

Registered: 02/23/03
Posts: 238
Loc: Canada
15 Amp three phase breaker

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


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