Disconnecting Means for HVAC Equipment

The disconnect has to be within sight — within 50 feet and visible — of the unit it controls. That way the person servicing the equipment controls the power and can lock it out.

These circuits use hermetic-motor sizing rules that differ from ordinary motors, so read the nameplate's minimum circuit ampacity and max fuse size rather than guessing.

When it applies

Air-conditioning and refrigeration gear needs a disconnecting means within sight of and readily accessible from the equipment. Within sight means visible and not more than fifty feet away. The point is simple: a tech at the condenser can kill and lock the power right there, without trusting someone at a distant panel.

Common mistakes

• Mounting the disconnect where the unit itself blocks the line of sight, that fails the within-sight rule.
• Landing the disconnect on the wall behind the condenser fan discharge and calling it accessible when it is buried.
• Sizing the disconnect and conductors off the nameplate FLA instead of the required minimum circuit ampacity and maximum overcurrent values on the label.

In the field

I read the two numbers on the data plate first, minimum circuit ampacity for the wire and maximum fuse or breaker size for the protection. Those govern the install, not the running amps I measure on a mild day.