DIY and Pro Help With Your Home Projects

Breaker Box Basics (Main, Circuit and GFI)

Breaker Box Basics
Understanding Breaker Basics (Main, Circuit and GFI)

There are 3 different types of breakers in your house, main, circuit and GFI. Understanding the difference is important for any home owner who ever opens their electrical panel.

Main The function of the main breaker is to shut off all electricity to the house if the combined load (all the circuits added together) approaches the safe limit of the electrical box or main service line. Every electrical component and wire has a maximum rated current. Exceeding this rating can generate more heat than the insulation can handle. If the insulation breaks down or melt, you have potential fire source. The main breaker is usually rate for 60 (on very old houses) to 200 amps. When the main breaker trips it will remove power from the entire house (if there are no uninterruptible power supplies).

Circuit breakers Each circuit in the house has an individual breaker that trips if the power exceeds the rated load on the breaker. Most circuits are 15 amps and most rooms will have more than 1 breaker controlling them. As with the main breakers, the circuit breaker is designed to limit the amount of power in a circuit so that the circuit cannot overheat and start a fire. When they trip they remove the hot leg of the power circuit but the neutral and ground legs are not affected.

There are 3 basic events that can trip the breaker

Peak load - If an appliance in your house has a short, the current can go very high very quickly. The breaker must disconnect the power very quickly before the wires in the house melt down or explode.

Continuous load - Each appliance in your house has a label that shows maximum continuous current. Appliances such as heaters and air conditioners can draw up to 15 amps, the maximum rating for many circuits. If you turn on a high wattage light on the same circuit, then the breaker will trip. This could be as little as 15.2 amps.

You or one of your children creates a short and is electrocuted. In this case the breaker will trip (if the current flow is high enough) to save you life.

Ground Fault Circuit (GFI)

GFI circuits are required (in most areas) by law for wet areas like kitchens, bathrooms and garages. When standard circuit breakers shut off, they kill power on hot leg only. It is possible that somehow the neutral or ground leg has become hot. Non-GFI circuits have no protection for this potentially deadly event. By remove power on both the hot and neutral legs, there is no way to complete the circuit. This reduces the chances of an electrocution.

Note: Electricity is extremely dangerous and working with house wiring is best left of a professional


Electrical work is highly dangerous. Let us help you find a great Electrician to do this job for you.

Need More Information? Check out our other articles on home wiring and electrical projects.

The information on this site is provided for reference only and is provided "AS IS", "AS AVAILABLE" with no guarantee of accuracy. Information comes with no warranties, express or implied. Use the information from this site at your own risk. See our disclaimer for more details.