Central AC outside Fuse Box

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Old 04-16-03, 06:57 PM
mrtoledo
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Central AC outside Fuse Box

What is the reason why a Central AC Unit has an outside fuse box instead of a circuit breaker. Even on new installations I see a fuse box used on the outside of the house. (The pull out type fuse squares).
 
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Old 04-16-03, 07:09 PM
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Generally, electrical code requires a local disconnect within sight of a motor.
Some A/C manufacturers require fuse protection (not circuit breaker) for the equipment. So the local disconnect gets installed as a fused disconnect.
 
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Old 04-16-03, 07:31 PM
mrtoledo
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Thanks...

Why would the manufacture require a fuse opposed to a circuit breaker. Does the fuse offer a better type of protection ?
 
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Old 04-16-03, 07:58 PM
texdiyguy
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The time/current characteristics of a fuse are much more precise than a breaker.
 
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Old 04-16-03, 09:14 PM
marako
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Aren't most, if not all, larger double pole breakers (i.e. 40 amp, 50 amp, etc..) rated as HACR (or something like this). Wouldn't this remove the need for a fused disconnect?
 
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Old 04-16-03, 09:36 PM
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Sometimes there isnt even any overcurrent protection there, its just a disconnect. There is just a plug in that box.
 
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Old 04-17-03, 04:38 AM
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Most HVAC manufacturers are listing the equip for a fuse or HACR circuit breaker. Some are behind the times, and keep the old listing for fuses only. If you compare the characteristics between a fuse and circuit breaker, they offer much of the same protection to the load. The additional benifit of a breaker is that the unit will never lose just one phase and burn itself out.
 
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Old 04-17-03, 09:53 AM
marako
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HandyRon,
I never thought of that. The main reason I don't like the fuse is that when they pop what do you do? Sure you can replace them, if the nearest supply house is open. So at 8:00pm Friday night when a freak thunder storm causes your AC fuses to pop your now stuck until Monday with no-AC. Not my Idea of fun.
 
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