A Hot Topic Electrical Concern

When home inspectors get their initial electrical training and continuing education courses, the history of problematic products is discussed. These discussions generally include Stab-Lok panels, Zinsco panels, and the older alloy 1300 solid aluminum wiring issues. These products have long been known to be fire hazards. Fortunately, even though some of these products are still present in older homes, they are no longer produced.

This brings us to a discussion of a product that is commonly used in HVAC installations—the pull-out disconnect switch. These disconnects are the least expensive units available, which makes them extremely popular. Several manufacturers produce this type of disconnect in both fusible and non-fusible models. Most are almost identical in size and design. The manufacturer’s name and logo on the boxes are the only noticeable differences.

All the manufacturers of the units refer to them as “air-conditioner disconnects,” or ACD. The intended use by one of the largest suppliers, Eaton, states: “Manufactured for use with lower load compressors with intermittent operation.” The instructions continue to state: “This ACD is not intended for uses on electric (EV) charging, photovoltaic, and resistive heating applications.” Eaton recommends another of their products with a 2-pole off/on switch for these applications.

The power to the appliance is turned on and off by inserting and removing a pull-out handle. Other types of HVAC disconnects use make/break switches like knife switches and molded case circuit breakers. One problem with the pull-out type is that sometimes the handle is not fully inserted into the contacts and does not get a good connection. The handle is encased in plastic and has metal blades that seat into the line and load stabs. 

A multi-family development in Columbia, Tennessee, has experienced multiple damaged disconnects that have been installed for use with attic air-handlers or furnaces. As many as 14 have melted and had to be replaced. One condo unit caught fire and was destroyed in December 2025. The models installed in this development were the Eaton DPU222R. Even though the electrical load was approximately 42 amps and the disconnect is rated at 60 amps, they still failed because of the continuous load and misuse.

A continuous load is where the maximum current is expected to continue for three hours or more. The manufacturers of HVAC equipment rate the minimum circuit ampacity for condensing units and heat pumps for continuous operation. Both heating and cooling loads can operate at maximum current for longer than three hours during extreme weather conditions in many parts of the country. 

Pull-out type HVAC disconnects are available in both fusible and non-fusible models and are typically rated at 30 or 60 amps. Both the fusible and non-fusible models have been known to have melting failures. 

This history of failures is concerning. As mentioned earlier, these disconnects are very common. They are used all over the country. Careful inspection of these devices is imperative for proper use and to reveal any signs of heat distortion. The failure point is primarily at the pull-out handle. Inspectors should look carefully for any deformation near the top of the plastic dead-front cover and pull-out handle. Recommendations for a different type of disconnect should be made when any evidence of damage, incorrect installations, and continuous load operation is observed. These recommendations could possibly save lives and prevent property damage. 

Mike Twitty retired from a 17-year home inspection career in 2021. He is a licensed electrician and an ICC-certified electrical code compliance inspector for residential and commercial installations. Twitty currently stays busy providing continuing education for home inspectors focusing specifically on electrical subjects. Learn more at homescantraining.net or by emailing mtwitty2@hotmail.com.