Air conditioner requires visible disconnect switch
Q. One problem I've noticed with home inspectors is they sometimes report defects that turn out not to be defective at all. Here's a case in point: An inspector cited my air conditioner for not having an electrical disconnect switch. I called an air conditioning contractor to repair this condition (not a free service call, I might add), and he said the disconnect switch was not missing. It was simply installed inside the air conditioner. If the home inspector had taken time to remove the exterior panel, he would have found the switch. Some inspectors, it seems, are not as smart as they might lead us to believe. What do you think about this?
A. Your question raises an important electrical-safety issue. Air conditioning equipment, by code, must have a disconnect switch that is visible and readily accessible. At the same time, the code permits the switch to be installed inside of the fixture, which would seem to be a contradiction, since an internal switch would not be visible or readily accessible. Fortunately, many HVAC contractors disapprove of internal switches on air conditioners. The reason for this disapproval becomes clear when we consider the intended purpose for the switch.
The primary intent of the National Electric Code "is the practical safeguarding of persons and property from hazards arising from the use of electricity." In keeping with this intent, the power to an air conditioner should be turned off when the system is being serviced or repaired. If a disconnect switch is installed on the outside of the unit, a contractor or technician can turn the power off before commencing work on the system. If the switch is on the inside, partial disassembly must take place before turning off the power. So, what happens if an electrical defect energizes the casing on an A/C unit? In that case, a shut-off switch inside the unit would not be helpful. Someone could receive an electrical shock by simply touching the fixture. That is why an external disconnect switch is the standard of the industry.
Another issue affecting internal shut-off switches is that they are subject to strict code requirements, and violations of these are common. For example, switches are sometimes installed within relay boxes, a condition that voids the A/C manufacturer's warranty. Additionally, a switch must be compatible with the horsepower rating of the A/C motor and must be rated to open if the motor is drawing locked-rotor current (whatever that means). Esoteric, to say the least; requiring the expertise of a qualified electrical specialist.
For home inspectors, the bottom line is this: Internal switches are unusual and are often installed in questionable ways. This is why home inspectors wave the proverbial red flag when there is no external switch for an A/C system. Home inspectors may sometimes report conditions that are not truly defective, but when electrical compliance is in doubt, it is better to err on the side of safety than to say nothing.
• To write to Barry Stone, visit him on the web at www.housedetective.com, or write AMG, 1776 Jami Lee Court, Suite 218, San Luis Obispo, CA 94301.
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