Electrical Panels Buying Guide

Components
Electricity comes into your home through wires that connect to your breaker panel. Understanding the components in a panel can help you make an informed decision when making your selection. A typical breaker panel consists of these primary components:

The main breaker is a large double pole circuit breaker that limits the amount of electricity coming in from outside to protect the circuits it feeds. It also identifies your breaker panel’s amperage capacity.
Circuit breakers are stacked in the panel and have an ON/OFF switch that controls the flow of power.
Bus bars receive power from the two thick black wires that bring power in from the electrical meter. The bus bars in turn carry power through the circuit breakers to the circuits.
Neutral bus bars connect to the main circuit’s neutral wire. The neutral bar provides the contact point for the white wires that return electricity back to the breaker panel after flowing through the black wires to power a device. Your home’s main grounding wire also connects to the neutral bar.
Grounding bus bars unite all the grounding wires from the breaker panel’s various circuits and connect them to the ground bar. It is also connected to a grounding conductor that leads underground, the metal enclosure and, if it’s the main service panel, to the neutral bar; the ground bar is not connected to the neutral bar at sub-panels.

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Types
There are different types of breaker panels to choose from, each of which meets a certain code requirement or application, depending on your area. Check with local authorities to determine which type of panel meets your local compliance requirements.

Main breaker panels have a built-in main breaker which can be used to shut off all power to your residence. A main breaker is a large double-pole circuit breaker that limits the amount of electricity coming in from outside to protect the circuits it feeds. It also identifies your breaker panel’s amperage capacity. Main breakers can be installed when the meter and feeder cable are within 10 ft. of the panel.

Main lug panels do not have a main breaker. Instead the line wires run to lugs. This type of breaker panel requires a separate disconnect. The main breaker, which would function as the disconnect, may be located at the meter, or if the main lug panel is used as a sub-panel, it may be connected to the breaker at the main panel. In the event of a fire, the separate disconnect at a meter can be helpful to fire authorities, who don’t have to enter the building to cut power.

Sub-panels are separate breaker panels that can contain new circuits, allowing you to readjust energy distribution to better handle your typical usage patterns. Also known as service or circuit breaker sub-panels, they can be a good solution when a breaker panel doesn’t have enough slots to add new circuits. A sub-panel is also ideal for situations where multiple circuits are needed in a single separate area, like a workshop or greenhouse. Be aware, however, that sub-panels do not increase the amount of available power. If an increase in electricity is needed, contact your local utility company or an electrician for increased service.

A sub-panel is typically powered by a circuit from within the main panel and does not have its own main disconnect.
The amp rating of the circuit in the main breaker panel must be the same or smaller than the rating of the sub-panel connected to it. Put another way, if the sub-panel is rated at 30 amps, the maximum amperage of the circuit in the main breaker would be 30 amps.
The only limit for the number of sub-panels you can have is the number of available circuits in the main breaker panel.

Transfer Switches are a type of sub-panel that transfers portable generator power into electrical power through your breaker panel. If you live in an area where storms are common, you may have a permanent back-up power generator that uses an alternative power source, like propane or natural gas. The generator can be wired directly to the household breaker panel, providing a seamless switch from utility service to back-up power when the electricity goes out. Some generators come with a transfer switch that carries the same rating as the home’s main breaker panel. There are two models of transfer switches:

Automatic transfer switches require a larger initial investment but provide continuous protection for homeowners.
Manual transfer switches are less expensive and require you to power up the generator and manually switch the load to the back-up system.

Read our Transfer Switches Buying Guide to learn more about transfer switches.

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Amps
Breaker panels are identified by the amount of amperage they provide. For example, a breaker panel of 100 amps will only allow 100 amps of electricity to flow through it without tripping. They’re also identified by the number of circuits they accommodate. For example, a 150-amp, 30-circuit panel can handle 150 amps of electricity with room for 30 circuit breakers.

When replacing your panel you’ll want to match the amperage capacity of your current model, or if your power needs have grown, upgrade to the capacity you need. The amperage will be identified on your current panel’s main breaker.
Amps typically range from 60 amps in older homes to as much as 200 in new construction.
One hundred amps is the minimum required by the National Electrical Code (NEC), but 150 is increasingly common.
While 100-150 amps are generally suitable for most homes, breaker panels are also available in 200- and 400-amp units.

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Circuit Breakers
The last factor to consider is to know the number and type of circuit breakers you require. This can vary, based on your needs. When making your selection, be aware that a circuit breaker is sized to operate at 80% of its rated capacity. This means that to operate safely, a circuit breaker rated at 20 amps should only carry a load of 16 amps.

You can calculate the total load for the circuit by adding up the loads of the devices that will run on it. These are usually identified on a sticker or label on the devices or appliance. If the load is calculated in watts, use this formula: amps = watts divided by volts. Example: 1,400 watts divided by 120V = 12 amps.

Different types of circuit breakers include:

Single pole, or 1 pole, circuit breakers provide 120 volts in various amp ratings. Single pole circuit breakers rated 15 to 20 amps are typically used for receptacles and lighting.

Double pole, or 2 pole, circuit breakers provide 240 volts in various amp ratings. Double pole circuit breakers are typically used for appliances and hot water heaters.

Arc fault circuit interrupters (AFCI) are designed to shut down power to a circuit when they detect arcs of electricity caused by worn or damaged wires. AFCIs are used to protect circuits in bedrooms and common areas.

Ground fault circuit interrupters (GFCI) break a circuit instantly when a short is detected. They are used to protect circuits in wet areas, like bathrooms, garages, unfinished basements and kitchens.

If you are upgrading your breaker panel to accommodate more 240V circuits for appliances that draw high current, like air conditioners and stoves, read our Circuit Breakers Buying Guide to learn more about these and other circuit breakers.

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