Sometimes the panel has clear labeling, but usually is doesn’t on these old panels. Pre-1965: Old panels that predate the CTL standard didn’t have a hard and fast rule for the number of circuit breakers allowed.

To help determine if tandem breakers are allowed, first consider the age of a panel. Panelboards must follow UL Standard 67, which requires all lighting and appliance panelboards to be Class CTL (Circuit Total Limiting). How does a home inspector determine whether tandem circuit breakers are allowed on the panelboard they’re inspecting? There are a number of ways to do so.

It’s perfectly fine to use tandem circuit breakers on any panelboard that’s designed for tandem circuit breakers, provided they’re installed in the proper locations. Because of this, they’re often referred to as “cheaters.”ĭespite the misnomer, this is not cheating. The next photo shows an older style tandem breaker found in Square D panelboards.īecause tandem circuit breakers allow for two circuits to be installed on a panelboard in a one circuit breaker space, they’re typically used after a panelboard has been filled to capacity with standard circuit breakers. The photo below shows a 60-amp two-pole circuit breaker at the top, then a 15-amp tandem circuit breaker (highlighted), then a 20-amp tandem circuit breaker (highlighted), then a 20-amp single-pole circuit breaker at the bottom. While a two-pole circuit breaker gets connected to two different poles at a panelboard and has a common trip or a handle tie for simultaneous disconnecting of two poles, a tandem breaker does not. People also refer to them as duplex, slimline, twin, half-height, half-inch, double, and wafer breakers, depending on local customs. A tandem circuit breaker is a double circuit breaker that takes up the space of a single circuit breaker on a panelboard. This is an updated version of an article I wrote for the ASHI Reporter back in 2011.įirst, a quick definition. I’ll explain what they are, when they can be used, and how a home inspector can figure all of this out. Today I’ll set the record straight on tandem circuit breakers.

150 amp panel ge