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#7698 - 02/16/02 06:27 PM fused or non fused
amptrap Offline
Junior Member
Registered: 02/09/02
Posts: 3
Loc: dallas tx
maybe i should already know this but i was wondering when you need a fused disconnect and when you dont. i was telling a friend he needed a fused disconnect on a duct heater because it had no internal overloads. it just had a disconnect switch for working inside the heater
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#7699 - 02/16/02 06:31 PM Re: fused or non fused
Nick Offline
Member
Registered: 08/13/01
Posts: 599
Loc: Riverside, CA
A heater would not require overloads. It is protected by the branch circuit over current device. A non-fused disconnect is fine in this application.
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#7700 - 02/16/02 06:34 PM Re: fused or non fused
amptrap Offline
Junior Member
Registered: 02/09/02
Posts: 3
Loc: dallas tx
so what is a good rule of thumb to use fused or non fused. does every resistive load not need a fused disconnect.
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#7701 - 02/16/02 06:55 PM Re: fused or non fused
Nick Offline
Member
Registered: 08/13/01
Posts: 599
Loc: Riverside, CA
Check the manufacturers nameplate. Most equipment will state weather or not a fuse is required. For instance, if a piece of equipment states a maximum fuse size of a specified value, you must use a fuse to protect the unit. Doing otherwise would void the listing and be a violation of 110.3(B). If it states maximum fuse or circuit breaker you could use either. You could use a breaker as protection and a non-fused disco at the unit.
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#7702 - 02/16/02 06:59 PM Re: fused or non fused
amptrap Offline
Junior Member
Registered: 02/09/02
Posts: 3
Loc: dallas tx
thanks a bunch nick i guess i never thought of it like that.
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#7703 - 02/21/02 03:10 PM Re: fused or non fused
Steve Miller Offline
Member
Registered: 08/30/01
Posts: 325
Loc: Loudoun Cty, VA
Be careful on the AC/Heat pump units. Some say max fuse size and some say max fuse/HACR CB size. If it says only max fuse then you need the fuse (someplace in the circuit) regardless of the breaker.
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