AskCodeMan

Hi Jerry

I know in "the old days" both split system components were wired to the same breaker....then things changed to require separate breakers. Is this a NEC requirement or equipment listing issue? If a NEC requirement do you know what year it took effect?

Just looked at a town home built in 1990 wired this way, 2 different wire sizes of course and a Challenger panel to boot. No empty space for another breaker.

David

David,

It never really was a code method to protect the air handler and the condenser unit with one breaker (at least not the way I saw it done in the past).

The breaker size needs to match the maximum for the unit, and needs to match the conductor size (nameplate rating and minimum conductor ratings take preference).

It is a bit difficult to have a 40 amp maximum breaker for the condenser unit on a conductor which also supplies the air handler which allows for a maximum of 40 amp ... the breaker would likely need to be at least a 60 amp to allow both to run properly and not trip the breaker ... and that size breaker would be too large for the nameplate maximum of either unit.

Conductor sizes would be the same way.

An exception would be to have a remote panel fed by a large enough circuit and breaker to operate both units, then feed off that panel to each with a separate breaker for each.