cirduit break for HVAC compressor or sub panel with fuse for compressor

[teachertwo]

Greetings all:

Have been advised that fuse holding sub panel to a HVAC split system compressor is needed rather than a dedicated main panel breaker only. Does this make sense to electrical safety/performance?

Old system was linked directly to panel breaker.

Also, if using a breaker only, should the break be higher amps than the compressor peak load?

...just a novice homeowner, so:


thanks for any advice

[jtrammel]

You have to have a service disconnect within line sight of the equipment, it doesn't have to be fused as long as it is protected at the breaker panel. Breaker/fuse should be sized according to manufactures specs of unit (located on nameplate of unit- min/max circuit protection or something to that affect.

[teachertwo]

Thank you, jtrammel, for this advice and detail. Though the circuit to the compressor has always been protected by its own dedicated breaker, one contractor advised the additional sub panel with fuse was "ordinary good practice". Thank you also for the sizing detail. I will make sure that is in the final work plan, too.

Much appreciated.

[jtrammel]

The contractor is probably proposing a service disconnect be installed. Is the existing breaker for the unit outside by the unit or inside the house/garage (out of line site of the unit)?

[teachertwo]

The existing panel and dedicated circuit is in line of site and close the existing and future compressor. I suppose the fuse panel add-on is a "service disconnect"...but dedicated breaker allows disconnect also (in my homeowner sense).

[timebuilder]

It is particularly important that the type of overcurrent protection be what is specified on the equipment label. IF the label says "FUSES" then fuses must be used. Since most homes have breaker panels, the needed fuses would be provided in the unit disconnect.

Today, equipment often species fuses OR breakers, so you can have an un-fused disconnect at the equipment WHEN "fuses or breakers" (or words to that effect) are used on the label.

[teachertwo]

Hello Timebuilder:

Thank you for this clear explanation