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#7698 02/16/02 09:27 PM
Joined: Feb 2002
Posts: 3
A
amptrap Offline OP
Junior Member
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 09:31 PM
Joined: Aug 2001
Posts: 599
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Member
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.

#7700 02/16/02 09:34 PM
Joined: Feb 2002
Posts: 3
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amptrap Offline OP
Junior Member
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 09:55 PM
Joined: Aug 2001
Posts: 599
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Member
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.

#7702 02/16/02 09:59 PM
Joined: Feb 2002
Posts: 3
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amptrap Offline OP
Junior Member
thanks a bunch nick i guess i never thought of it like that.


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#7703 02/21/02 06:10 PM
Joined: Aug 2001
Posts: 329
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Member
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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