Can lights and sockets be on the same circuit?

Having lights and sockets on the same circuit can be convenient, but is it technically possible and feasible, and what do the electrical codes recommend?

Of course, it is possible to have lights and sockets on the same circuit. Circuit breakers can be used for both lighting and sockets as long as the total load does not exceed 80% of their rated power. Typically, a 15 A circuit breaker is installed for general use, which can be used for both purposes at the same time. However, this may not be practical, especially when used on thin wiring and when used with appliances that draw high currents. Also, it may be prohibited in some places. If you can, separate the two groups of circuits for greater convenience.

National Electrical Code (NEC) recommendation: The National Electrical Code (NEC) allows lights and sockets to be powered from the same circuit, as long as the circuit is properly sized and installed to prevent overload and ensure the safety of the electrical system. 

Fixture type	POWER	chain required
Lanterns	Up to 180 W	15 amp circuit
Shops	Up to 1,440 W	15 amp circuit
Lanterns	180 - 720 W	20 amp circuit
Shops	1,440 - 2,880 W	20 amp circuit
Lanterns	More than 720 W	30 amp circuit
Shops	More than 2,880 W	30 amp circuit

The presence of lamps and sockets in the same circuit

The presence of lamps and sockets in the same circuit is technically possible.

There are no technical barriers to your fixtures and sockets using the same circuit. They can easily exchange chains. In fact, it was commonplace in the first half of the 20s.^th century, when most homes had only simple household appliances and, accordingly, less stress on electrical circuits. Whether they should or not is another matter.

Therefore, if you prefer, you can use the same circuit for lighting and appliance outlets, as long as you don't share lighting circuits with high-power appliances and your local codes allow it.

Before looking at the legal aspects, let's look at more advantages and disadvantages of both scenarios.

Advantages and disadvantages

It would be better to consider the advantages and disadvantages when deciding whether to separate or combine lighting and electrical outlets.

The main advantage of separating them is that it will be cheaper to install a lighting circuit. This is because lamps use very little electricity, so you can use thin wires for all your lighting circuits. You can then use thicker wires for the outlets. In addition, it is recommended not to use common lighting circuits with powerful appliances and use separate circuits for those that consume the most current.

The main disadvantage of combining both is that if you plug an appliance into a circuit and get an overload, the fuse will also blow and turn off the light. If this happens, you may have to deal with the problem in the dark.

However, if you have a lot of wiring, maintaining two separate sets of wiring circuits can become cumbersome or unnecessarily complicated. To avoid this situation, or if you have a large house or mostly small appliances, then combining them should not be a problem. Another solution would be to create separate sockets for only your high power appliances and, preferably, organize dedicated circuits for them.

However, it should be clear that separating the lighting circuit from the outlets, which will prevent any device or appliance from being connected to the lighting circuit, is less costly to organize and is a safer and generally more convenient option.

Local rules and regulations

Some local codes and regulations determine whether you are allowed to have lights and sockets on the same circuit.

Somewhere it is allowed, but somewhere not. If there are no restrictions, you can use the same schemes for both use cases, or set separate connection schemes for each.

You should check your local codes and regulations to find out what is allowed and what is not.

power consumption

Another way to look at whether you can or should have lights and sockets on the same circuits is to take into account power consumption.

Typically, a 15 or 20 amp circuit breaker is installed to protect general purpose circuits. This means that you can safely use devices and appliances that together draw no more than 12-16 amps, respectively. You can safely use lighting fixtures and other appliances together, but only as long as the total power consumption does not exceed the power consumption limit.

The potential problem only occurs if the current exceeds 80% of the circuit breaker rating.

If you can share circuits between lighting and appliances without exceeding the limits, you can happily continue to do so. Otherwise, if not, you have the following options:

• Either install a higher rated circuit breaker to allow for multiple uses (not recommended);
• Alternatively, separate circuits for lighting and sockets for other appliances;
• Better yet, install dedicated circuits for all your high power appliances and don't use them in lighting circuits.

Considering the size of the room

A professional electrician would approach this issue by also considering the floor area or the size of the room in your home.

First, it should be noted that high power appliances such as irons, water pumps and washing machines are not included in these calculations as they must be on separate dedicated circuits. You will need to determine the area of ​​each room in your home. We will then apply the 3VA Rule.

For example, a room measuring 12 by 14 feet covers an area of ​​12 x 14 = 168 square meters.

Now multiply this by 3 (the 3VA rule) to determine how much power the room needs (for general use): 168 x 3 = 504 watts.

If your circuit has a 20 amp switch, and assuming your mains voltage is 120 volts, the circuit's theoretical power limit is 20 x 120 = 2,400 watts.

Since we must only use 80% of the power (so as not to stress the circuit), the actual power limit will be 2,400 x 80% = 1,920 watts.

Applying the 3VA rule again, dividing by 3 gives 1920/3 = 640.

Therefore, a general purpose circuit protected by a 20 A circuit breaker is sufficient for an area of ​​640 square meters. feet, which is much more than the area occupied by rooms 12 by 14 (i.e. 168 sq. feet). Thus, the scheme is suitable for the room. You can even combine schemes to cover more than one room.

Whether you use lights, other devices, appliances, or a combination of the two, as long as the total power consumption does not exceed 1,920 watts, you can use it for general purposes without overloading it.

F.A.Q.

How many lights and outlets can I use?

You may be wondering how many lights and sockets you can install, or how many (general purpose) electrical devices and appliances you can use at the same time.

As a general rule, you can safely use 2 to 3 dozen LED bulbs per 15- or 20-amp circuit, since each bulb usually does not exceed 12-18 watts. This should still leave enough room for non-essential (non-powerful) appliances. As for the number of appliances, you should use appliances that do not exceed half the rating of the circuit breaker. This means that you should consider about ten as the maximum in a 20 amp circuit and eight in a 15 amp circuit.

However, as shown above with calculations, one should actually pay attention to the total power working at the same time, so that the current does not exceed 80% of the breaker limit.

What wire size should be used for the lighting circuit?

Earlier I said that only thin wires are needed for the lighting circuit, but how thin can they be?

You can usually use 12 gauge wire for individual lighting circuits. The size of the wire is independent of the size of the circuit breaker, whether it's a 15 or 20 amp circuit, as you usually won't need more.

Summing up

Don't worry about combining lighting and sockets on the same circuits. Make sure you don't use any powerful devices or appliances on them as they should be separate dedicated circuits. However, you can separate lighting and socket circuits for the benefits mentioned above.

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