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How Many Lights On A 20 Amp Circuit

Understanding the various text terms about circuits, lighting, and outlets in home improvement and electrical systems is crucial for ensuring safety and efficiency. Knowing the relevant terminologies and electrical principles is essential for homeowner or electrician, from the types of new lights to circuit breakers.

One important consideration is the concept of a single circuit, branch circuit, and more to know how many lights per circuit you can have. Whether to run lights or outlets, each could be on a dedicated circuit or share one with others, depending on factors like amp rating and voltage requirements.

Regarding amp ratings, 20-amp circuit breakers are commonly used in homes to handle higher electrical loads. These circuits can accommodate multiple LED lights or outlets, and it’s essential to adhere to the guidelines set by the National Electrical Code to ensure proper installation and safety. When dealing with LED lights, understanding their wattage and brightness equivalence to traditional light bulbs, like 60-watt incandescent bulbs, can aid in selecting the right LED replacements.

Number of lights on a 20-amp circuit

The gauge of wire used is also crucial, as it determines the maximum wattage and electrical capacity a circuit can handle without tripping the breaker. Using the appropriate wire gauge ensures efficient electricity flow and minimizes the circuit overload risk. Whether choosing LED bulbs, calculating amp ratings, or designing lighting systems, understanding these terms is essential for a safe and successful electrical setup in any home.

In our guide, you can learn more about the number of lights on a 20-amp circuit and possible numbers of receptacles using a 20 amp breaker and circuit. By the end, you’ll better understand your overhead lighting requirements. Also, when you want to know how many lights can I put in a certain area, you’ll be able to calculate the answer. (Learn How Long Can You Turn Off Water To Toilet)

Understanding 20 Amp Circuits

What is a 20 Amp Circuit?

The wire on a 20-amp circuit is standard as a residential electrical circuit wired with 12 gauge wire and protected by a 20 amp circuit breaker. It carries electricity at 120 volts, giving it a total power capacity of 120V * 20A = 2400 watts.

This allows receptacles on a 20 amp circuit to power devices as well as powering multiple lights around the home. The 20 amp circuit is versatile enough to provide electricity for general lighting and receptacle needs in many household rooms.

How Many Lights Can a 20 Amp Circuit Handle?

A single 120-Volt circuit at 20 amps using efficient LED bulbs can handle around 350 5.5-watt bulbs based on the recommended derated capacity of 1920 watts. The number of lights a 20-amp breaker and circuit can accommodate depends on the wattage rating of the actual LED or other bulb types. Lower wattage CFL or LED bulbs allow more fixtures to be installed on the circuit since they consume less electricity individually.

Incandescent or halogen lights use more watts per bulb, so less can be connected to a 20 amp lighting circuit without potentially overloading the breaker or the light switch. When calculating capacity when you put lights, factor in the wattage of the specific bulbs you plan to use. (Learn How Many Lights On A 15 Amp Circuit)

Optimal Wattage and LED Lights on a 20 Amp Circuit 

For optimal efficiency and capacity, choose ENERGY STAR-certified LED bulbs in the 5-15 watt range to allow the greatest number of lights on a single 20 amp circuit. Look for LED bulbs that provide equivalent brightness as a 60-Watt light but only consume 10W of electricity. Good options are like the SYLVANIA ECO LED A19 Light Bulb; you can have multiple lights on a circuit with these.

CFL bulbs are another excellent option that operate at about 15W while producing similar light output as 60W incandescent. Using the lowest wattage of LED or CFL bulbs allows the highest number of fixtures to be powered within the capacity of a 20-amp residential lighting circuit. 

To avoid overloading and to find a circuit can safely run everything on it. You use the 80% electric code. So, for electrical outlets or lights, you wouldn’t go above 16 amps on a 20 amp circuit or no more than 1440 watts on an 1800 watts circuit.

Calculating Total Lights for 20 Amp Circuit

Calculating Total Circuit Capacity:

The first step in determining how many LED lights can be installed on a 20 amp circuit breaker is calculating the total capacity of the circuit. This can be done using the simple formula: watts = volts x amps. For a typical 120 volt circuit with a 20-amp breaker, the calculation would be 120V x 20A = 2400 watts. This 2400 watts is the total capacity that circuit can handle.

However, best practice electrical design recommends derating a circuit’s maximum capacity by 20% as a safety margin. With a 20% derating, the usable capacity of a 120V 20A circuit would be reduced to 1920 watts.

This derated wattage of 1920 watts is the maximum lighting load that should be installed on that circuit. Exceeding the derated wattage risks overloading the circuit, which can lead to nuisance tripping of the breaker or potentially dangerous overheating of the circuit wiring. By first calculating the total derated wattage capacity. You can determine the maximum number and size of light fixtures to be safely powered on a 20 amp home lighting circuit. (Read Wire Size For 100 Amp Service 150 Feet)

Mixing Lighting Types

When installing mixed lighting types on a 20A circuit, you need to:

  • Add up the wattages of all the bulbs and fixtures you plan to use. This may include LED, CFL, halogen, incandescent, or fluorescent bulbs.
  • The total combined wattage of all lighting should not exceed the derated circuit capacity, typically 1920W.

By accounting for the wattage consumption of all the lights on a single circuit, you can ensure the circuit does not become overloaded. Overloading can lead to nuisance tripping of the breaker or dangerous overheating of the wiring.

Choose more energy-efficient LED or CFL bulbs that consume less wattage when possible. This will allow more fixtures to be safely installed on the lighting circuit.

Recommendations by Room

  • Bedrooms, bathrooms, and garages typically can be wired on general-purpose 20A lighting circuits and draw more than 1.5 amps or 180 watts. Bedroom lights consume less power.
  • However, kitchens may require dedicated 15 or 20 amp circuits as stipulated by electrical code due to the number of appliances used.
  • When wiring kitchen lighting, carefully review any code requirements for dedicated circuits or limitations on lighting and receptacles sharing a circuit.
  • Too many outlets on the same circuit risks overloading and potential electrical hazards or damage.

Understanding Multiple Lights on One Circuit

A more common wire for lighting has less capacity, so it isn’t suited to running large appliances. Here’s a bit more on using a 15a circuit and 15a breaker, and how many lights can you put on them? 

Use of a 20A breaker for a lighting circuit in a residential occupancy is not permitted. It violates the law (CEC). Use only a 15 amp breaker. At most, twelve lights should be installed on a 15-amp circuit, regardless of the bulb wattage, or it could cause the breaker to trip.

Combining Lights and Receptacles

When installing lights and receptacles on the same circuit, check your local electrical code for any prohibitions on combining lighting and outlets. Some codes do not allow lights and receptacles on the same circuit.

If combined, all lights could go dark if an overloaded receptacle trips the breaker. Separate circuits for lighting provide redundancy if the receptacle circuit breaker trips. Combination circuits also require more robust wire gauges to handle the increased amperage load.

The extra cost of separate circuits may be worth the investment over a building’s lifetime. Consult a qualified electrician to ensure compliance with local codes and safe electrical practices when combining lighting and receptacles on 20A home circuits. (Learn How Many Amps Does A Ceiling Fan Use)

20 Amp circuit Capacity


Does 20A circuit need derating for LED inrush current?

Some LED drivers may cause a brief surge of **inrush current** when first turned on. This can potentially trip a 20A breaker. Check manufacturer specs and further derate circuit capacity if needed.

How many 50W lights on 20A circuit?

With 80% derating, a 120V 20A circuit can safely handle around 38 x 50W light bulbs.

How many 100W lights on 20A circuit? 

Approximately 19 x 100W incandescent bulbs could be installed on a 120V 20A residential lighting circuit.

How many 8W LED bulbs on 20A circuit?

 A 20A 120V lighting circuit with an 80% derating could accommodate about 240 x 8W LED bulbs.

How many watts on a 240-Volt Circuit of 20A?

At 240V, a 20A circuit can deliver 4800 watts. But derating to 80% gives a capacity of 3840 watts for safe operation.

How Many Lights On A 20 Amp Circuit