If your breaker/disconnect is within sight and not more than 50 feet away it doesn't need it to be lockable, but ALL ungrounded conductors have to disconnect at the same time (approved common tie handle).
If you can't satisfy both of the above then install a disconnect switch by the unit.
NEC 2008
210.4(B) Disconnecting Means. Each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates.
422.31(B)
Appliances Rated over 300 Volt-Amperes or 1/8 Horsepower. For permanently connected appliances rated over 300 volt-amperes or 1/8 hp, the branch-circuit switch or circuit breaker shall be permitted to serve as the disconnecting means where the switch or circuit breaker is within sight from the appliance or is capable of being locked in the open position. The provision for locking or adding a lock to the disconnecting means shall be installed on or at the switch or circuit breaker used as the disconnecting means and shall remain in place with or without the lock installed.
The AHJ may have meant CBC 2010 (California Building Code) it refernces NEC 2008
