Originally Posted by
Rollie Meyers
if A/C data plate states "maximum fuse or HACR circuit breaker size __" a non fusible disco may not be used.
Rollie,
With a non-fused disconnect at the a/c condenser unit, there would be a fused disconnect at the supply to those circuit conductor, which most likely originate at a panel and are protected by the breaker (or fuse) at that panel. The conductors are *required* to be protected on their supply end.
Once protected, the name plate on the a/c disconnect does not require an additional overcurrent device (breaker or fuse) - unless the first overcurrent device is too large, in which case a lower rated overcurrent device could be installed in place of the first overcurrent device, or, a lower rated overcurrent device could be added at any convenient point (which is most typically at the required disconnect for the unit).
Now, to take this a little further, if the name plate states "Max Fuse Size" ... a "fuse" must be used for overcurrent protection, not a breaker.
Most modern units will state "Max Fuse or HACR Breaker Size", meaning that either may be used.
The maximum nameplate rating has nothing to do with using a fused or non-fused disconnect.