Tandem Breakers: What You Need to Know

Does your home or building need tandem breakers to meet your electrical output requirements?

If so, you must first understand wherethey can be installed, if at all, or these powerful breakers will end up doing more harm than good.

What Is a Tandem Breaker?

Tandem breakers are extremely easy to identify. Their name says it all. If you look at a slot that was made for a single circuit breaker and, instead, you find two narrow breakers, you’ve identified a tandem breaker.

Many electricians even call them “cheater” breakers for their ability to fit two into a location designed for just one. These breakers are used when the entire panel has otherwise been filled to capacity, meaning they’re the only option for adding to its capability.

Other prefixes you may hear attached to these types of breakers include:

• Double
• Duplex
• Half-height
• Half-inch
• Slimline
• Twin
• Wafer

Your typical two-pole circuit breaker connects to a panelboard through two distinct poles. It has a common tip so as to disconnect from these two poles simultaneously. Tandem breakers do not have this kind of connection.

Are “Cheater Breakers” Safe?

Given this common alternative to their name, many people worry that tandem circuit breakers may be dangerous, that they may somehow overtax the panel and lead to blowing circuits or even something much worse.

Fortunately, despite that moniker, tandem circuit breakers are completely safe to use provided your panelboard was meant to house them and that you install them in the correct locations.  

If these devices were dangerous, GE tandem breakers, Square D tandem breakers, and options from other well-respected brands wouldn’t exist.

Does My Panelboard Allow Tandem Circuit Breakers?

Nonetheless, despite the fact that some very popular brands manufacture tandem circuit breakers, you still need to know how to check if your panelboard allows them or installation could be extremely dangerous.

Check the Model Name of Your Circuit Breaker

The first thing to check is the name of your panelboard. You’ll find your answer in the first four-digit number.

For example, a G3040BL1200 tells you that it offers 30 spaces but can support 40 total circuits. The only way it could do this is if it allows for tandem circuit breakers.

On the other hand, if your panel is a G3030BL1150, you know that it has 30 spaces but only allows for 30 circuits. If you installed even one tandem breaker, you’d exceed that amount, so this panel does not allow for them.

Check the Panelboard’s Diagram

If you don’t know the model name of your panelboard, you can always check its diagram. This will show you not just iftandem breakers are allowed but, if so, where they can be installed.

Those slots that only allow full-sized breakers will be empty. Those that allow for tandem breakers will feature a single line inside the slot.

Another way of showing this will be a diagram that has one single line, representing the entire panel, with individual lines sprouting off it, representing the breakers. Any line that turns into two (these lines usually have a marked “hump” to them) shows you where tandem breakers are allowed, if at all.

Many diagrams offer some kind of key, so be sure to check for that before trying to interpret it. For example, some panelboard diagrams will show lines in each and every empty slot, though that actually represents only full-sized breakers.

Properly Using Tandem Breakers

Whether you use GE tandem breakers, Square D tandem breakers, or some other brand, they are an incredibly convenient and cost-effective way to get more output from your panel. However, don’t risk trying to install them where they’re not supported or you’ll have a potential fire hazard on your hands.

In the case where tandem breakers have been used where they don’t belong, the best path forward is to replace the entire panelboard to avoid any future problems due to the damage these breakers may have already caused.