How Many Breakers Can An Electrical Panel Have?

Electrical panels built into homes to distribute the incoming electricity supply to different circuits have limitations on the number of individual breakers and circuits they can house. The NEC previously regulated the maximum number of breakers an electrical panel can have, but this has changed over the years. So how many breakers can electric panels support?

The number of circuits and breakers you can install in an electrical panel is limited by the panel’s design. Most 200 amp panels will have 40 breaker slots but can accept more circuits with tandem breakers. 120v single-pole breakers will use 1 breaker slot, while 240v double-pole breakers will use 2 breaker slots. Manufacturers rate their panels and limit the number of electrical circuit breakers based on that rating. The main disconnect size must comply with the panel rating.

Panel RatingNumber of Spaces/SlotsNumber of Individual Circuits
200 amp40 80
150 amp3060
100 amp1224
The number of breaker spaces and circuits vary by manufacturer

Manufacturers make different sized electrical panels for different applications in the home. The design of these panels is to contain a specific number of breakers. Knowing what these maximums are is crucial information you need when planning any extensions or additions to the electrical system in your home. Let’s take a look at what the restriction is so that you keep your home within code.

How Many Breakers Are Allowed In A Panel?

Historically, the number of overcurrent devices or circuit breakers allowed in an electrical panel was controlled and regulated by the NEC to be no more than 42 breakers.

Since 2008, the NEC no longer stipulated a maximum number of circuit breakers. The new specification is that the number of circuit breakers installed must not exceed the designed number of breakers the panel board can hold. Article 408.54 of the NEC is where you can find this prescription deferring to the manufacturer’s instructions.

Therefore, the circuit panel manufacturer will indicate the maximum number of permitted circuit breakers for fitment in the electrical service panel. Manufacturers make electrical panels in different sizes for different applications, which results in a varying maximum number of breakers, depending on the panel’s rating.

There is a link between the rated number of circuits of a panel and the number of amps the panel can handle. For example, a 100-Amp service panel box may limit you to a total of 20 circuits and thus a maximum of 20 circuit breakers. The rating of other panel boxes could be with a 20/24 designation. This rating means that the panel can have 20 circuit breakers but a total of 24 branch circuits.

If the panel allows for more circuits than circuit breakers, a certain number can be tandem breakers. This configuration allows connection to two circuits. The proviso is that the total amps on both circuits do not exceed 80% combined load of the breaker amperage.

So how many circuit breakers can you install in a 200-amp service panel? You can install as many circuit breakers as slots in the electrical panel because all circuit breakers are unlikely to draw current at full electrical capacity simultaneously.

Only once the total amp draws from all the individual circuits exceed the main breaker switch capacity will the main breaker trip.

The rating of an electrical panel relates to the maximum rating of the main supply circuit breaker used to disconnect from the main supply.

What Is The 6 Throw Rule?

The six throw rule is a safety measure put in place by the NEC to allow for safe, fast cutting of the electrical supply to a structure.

The six-throw rule states that you must install a central mains breaker if more than 6 circuit breakers are in a panel. This central breaker will disconnect all the circuit breakers from the main supply in the electrical panel. The reference for this restriction is in 230.71 Maximum Number of Disconnects (A) General in the NEC.

This six-throw rule is sometimes referred to as the six-hand rule or six-hand movement rule and relates to the number of hand movements required to disconnect the entire circuit breaker panel from the main electricity supply.

How Many Breakers Can You Have On A 60 Amp Panel?

If your home has a 60-amp panel installed, the chances are that the house is very old. Most houses that use 60-amp panels were constructed between 1955 and 1965 and are inadequate for most modern homes.

The older homes using these panels were not even fitted with circuit breakers but fuses instead. If your home has a 60-amp panel, you will need to upgrade the panel before changing the electrical system.

The minimum amperage panel for modern homes is 100, 150, or 200-amps. The NEC does not allow installing panels rated below 100-amps as the main electrical panel for the house.

Modern 60-amp electrical panels are purpose-built as sub-panels and generally only have 8 to 10 slots available for circuit breakers.

If your home only has a 60-amp panel, the electricity coming into your home will probably also only have a rating of 60-amps. You need to contact your energy provider to increase the current coming into your home when upgrading the panel to a higher amperage.

How Many 20 Amp Breakers Can I Put In A 100 Amp Panel?

The limitation of the number of circuit breakers you can put in a 100 amp panel is by the number of available slots in the panel. Most 100 amp panels have 20 spaces available for circuit breakers.

Larger capacity 100-amp panels are available, which have more spaces for breakers. Still, this configuration may only allow a limited number of 20-amp circuit breakers mixed with other rated breakers not to overload the main supply breaker.

The panel manufacturer will give instructions on the panel as to the number of various rated breakers the panel can support.

If you have double-tapped breakers or more circuits than you do breaker slots, adding a tandem breaker will allow you to install two circuits into one breaker safely.

You can, in essence, double your electrical panel capacity by replacing a standard breaker with a tandem breaker.

Can A House Have More Than One Breaker Box?

A house can only have one main circuit breaker box, but it can have several sub-panels, particularly if the supplied building is not joined directly to the main house. If the distance from the main panel is too far, this can be another scenario where a sub-panel makes practical sense.

Most sub-panels will also have a circuit breaker in the main panel to disconnect the sub-panel from the main supply at this location.

How Can You Tell If A Panel Is Overloaded?

Too many circuits in a breaker panel or simultaneous operation of too many high-usage electrical appliances are possible and cause concern. This overload can cause frustrations, but more importantly, it can be a safety hazard for your home.

There are several telltale signs that your breaker panel could be overloaded.

  • The mains supply circuit breaker trips frequently.
  • After the main circuit breaker trips, it won’t easily reset.
  • The switches and wires become noticeably hot in the panel.
  • A burning smell is emanating from the panel. This smell can indicate overheating, which melts and burns insulation and wiring.
  • Is there any visible physical damage to any wires or switches in the panel?
  • Is there a buzzing or humming of the gear in the panel? A high current level pulled through the equipment can generate this noise within the equipment housed in the panel.

Any of these clues are an indication that the electrical panel could be overloaded, and you should get a licensed electrician to come out and evaluate the system.

How Much Can My Breaker Box Handle?

The main breaker box for your home will only handle the current it is rated for and is limited to the size of the breaker and the amount of current coming in from the main supply.

Modern main breaker boxes are generally rated to handle 100, 150, or 200-amps. The intention for 100-amp breaker boxes is for use in small homes up to 1200-square feet. Breaker boxes rated for 150-amps would be for medium-sized homes and 200-amp service panels for large homes with large air conditioning and heating demands.

Do Breaker Boxes Have Fuses?

No, breaker boxes do not have fuses. Many older houses still have fuse boxes with fuses. However, breaker boxes utilize circuit breakers instead. You can’t use fuses inside breaker boxes and vice versa.

Circuit breakers are much safer and can trip with an overcurrent. When a breaker trips, it can be reset. With fuses, an overcurrent will blow a fuse requiring replacement.

If your home still uses fuses, electricians and industry experts advise having electric upgrades as soon as possible. If you have fuses, you likely still have some obsolete electrical wiring, like knob and tube, which is a fire hazard. Electrical upgrades would probably lower home insurance premiums.

Conclusion

The NEC previously dictated that 42 dedicated circuits were the maximum that could be installed in any single electrical panel. This stipulation has been removed from the code and has been replaced by recommending following manufacturer instructions.

Electrical panel manufacturers must rate their products with maximum ratings and advised connection configurations. As long as your electrical system complies with the manufacturer’s requirements, the panel is considered compliant with the code.

References

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Hubert Miles

I've been conducting home inspections for 17 years. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.
DISCLAIMER: The content published on HomeInspectionInsider.com is not professional advice. You should consult with a licensed professional and check local permit requirements before starting any project.
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