How Many LED Lights Can You Use Per Circuit?

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Safety should be the primary concern when working on anything with electricity within the home. It is recommended to always get a professional to do any work with electricity. Everyone is well aware of the benefits of using LED lighting in your home, from the superior lifespan to decreased power consumption. But is it as simple as swapping out your existing fixtures with LED lights?

How many LED lights you can connect to a circuit depends on several factors, including the circuit breaker amperage rating, the supplied voltage in your area, and the bulbs’ wattage. For example, a 15-amp circuit could power up to 560 low-power LED bulbs, with that figure decreasing with an increase in lumen rating.

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Each of these factors is important to check up before beginning a renovation project, so continue reading to understand better each factor and how it may impact your LED lighting plans.

Circuit Breakers and Amperage

Circuit breakers come in various amperage ratings, from 1 amp up to 125 amps, and it’s essential to give heed to these ratings. If the rating is too high, it won’t be performing its protective role. If it’s too low, it will constantly trip even when functioning normally.

Typical Household Circuit Amps

The typical home uses anything between 10 amps and 25 amps in total. A distribution board, often called a DB board, consists of multiple circuit breakers. 

This is to isolate each circuit so that if one gets overloaded, the rest don’t trip as well. These circuit breakers in a typical home would range from 1 amp, for lights and lesser loads, up to 15 amp for heavier appliances like water heaters.

When wiring a house’s electrical cables and installing a circuit board, it is important to properly calculate the correct amperage rating for the circuit breaker you will require (source).

It goes without saying that for higher amperage circuits, the correct gauge of wire would need to connect the circuit breaker to the outlets. We discuss how the wire diameter affects the functioning of a circuit more in our article “Can I Use 12-Gauge Wire on a 15-Amp Circuit?

The 125% Rule

The general rule for circuit breakers is to accommodate 125% of the total amperage draw.

Let’s say, for example, you had LED bulbs that you knew drew three amps of power, and you wanted to install four in one circuit to light up your lounge. This means you’d be drawing 12 amps in total on that circuit, so it would be advisable that you install a 15-amp circuit breaker.

The extra 25% allows for minor fluctuations in supplied electricity. The electrical power coming into your home is, after all, alternating current.

Ohm’s Law: The Science Behind It

Central to calculating how many LED bulbs a circuit can power is Ohm’s Law. Ohm’s Law describes the relationship between a circuit’s voltage, the flow of electricity, and the resistance it experiences while flowing (source).

It may be easier for those new to the fundamentals of electronics to relate electricity to water flowing in a pipe.

For water to flow from one place to another, there needs to be pressure driving it. In electrical terms, this describes voltage — the electrical potential between two points.

Next, the diameter of the pipe determines the rate at which the water flows. This describes current, with electrons moving along the circuit. This is a necessary distinction to make from voltage since the two are often confused.

Finally, there is sometimes resistance in the pipes, which affects water flow, such as a blockage or a closed tap. This represents components that use electricity to function or intentionally affect electricity flow in some desired way.

Importantly, Ohm’s law states that any change in one of these factors would impact the other. If the water or electrical system’s resistance stayed the same, but the water pressure or voltage increased, the flow of water or current would naturally increase as well.

Armed with this knowledge, along with all of the other components in your home’s circuitry, you can begin to calculate how many LED lights you could use in each circuit.

Low-End Example

First, let’s look at a low-end example. Let’s say you were looking to replace all of your household bulbs, totaling 20 across all the rooms, with 40-watt-equivalent LED bulbs. 40-watt incandescent bulbs produce 450 lumens, something which 5-watt LED bulbs can easily produce.

This means your total power draw would be 100 watts and would use 0.41 amps if they were all switched on simultaneously.

You’d be able to easily get by with a 1A circuit breaker and even have more room for extra lights or other components on this circuit.

Mid-Range Example

450 lumens are great for ambient light, but what if you needed something brighter, like a reading light or a kitchen.

100-watt incandescent bulbs often get used in these cases, producing a more substantial 1800 lumens. The LED equivalent for that lumen rating uses 20 watts of power.

Though it is a bit of overkill, let’s say we were looking to install 20 of these bulbs to ensure good coverage in these important areas — the total power draw would be 260 watts while drawing just 1.66 amps.

Once the 125% rule has been applied to this total, we arrive at a little over 2 amps. It’d be safer to use a 3 amp circuit breaker then.

High-End Example

LED lighting projects aren’t just limited to the house — what if you were looking to create an in-store display or something else that really required the brightest lighting possible?

Incandescent bulbs peak at 150 watts, which produce 2800 lumens. LED bulbs are able to produce the same amount of lumens while only requiring 28 watts of power.

If we wanted to build a display that housed 30 of these high-powered lights, the total power draw would be 840W. These lights would draw 3.5A of current too.

Once we’ve applied the 125% rule — since we still want the display to be safe — we’d need a circuit breaker with an amperage rating of higher than 4.4 amps. This would mean a five-amp circuit breaker would suffice.

Mains Voltage

Another important point to consider regarding how many LED lights you can use in a circuit is where in the world you are.

Residential voltage differs across the world (source). Plug types vary as well, but these are merely adaptations to suit the voltage and frequency of the transmitted alternating current.

As we will see in the final section that ties everything together, a change in voltage in the circuit that we’re working on could drastically change our calculation of how many LED lights we can use at once.

This is also an important point to remember since components are manufactured to work under specific conditions. Therefore, it is critical to use compatible electronics, such as circuit breakers, bulbs, and switches.

There are some occasions where components can work outside of their specifications, but in general, the best-case scenario is that the circuit won’t operate. In some cases, far worse things can occur, like component damage or even electrical fires and overload.

Bulb Wattage

We touched on how bulbs work under circuit breakers, but there is a lot more to them than that!

Bulbs are given certain specifications based on how they operate. This helps consumers ensure they are buying compatible components and that it will have the desired effect.

Before LED bulbs, the primary measure of how bright a bulb was when it was lit was its wattage. In essence, a watt is an energy unit that measures how much energy the bulb generates while creating light (source).

Incandescent bulbs force electrons, supplied by the flow of electricity, through its tiny coiled wire, generating heat. At a certain point, where the heat is sufficient, it becomes visible light.

LED bulbs work slightly differently in that the electrons are instead forced through a diode. 

The wiring between light fixtures also makes a difference to their overall amperage draw. Home lighting setups traditionally favor parallel circuits since wiring them in series poses safety risks, as covered in another of our articles, “Can I Wire Lights in Series?

When LED bulbs were developed, it became apparent that a bulb’s wattage shouldn’t be the measure of how bright the bulb is. LED bulbs are known to be far more energy-efficient while doing the same job. This saw a new measure being promoted.

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Lumens is the unit of measure of brightness, a departure from wattage, which was actually a unit of power consumption (source). 

This became an important distinction to make since LED bulbs achieved the same levels of brightness at a much lower wattage.

To exemplify this, consider a standard household bulb. In the past, many would have used a 60-watt bulb, which, as we know today, produces 800 lumens. An LED bulb can generate the same level of light while only using 9.5 watts, doing the same job over 6 times more efficiently!

LED vs. Standard Bulbs

Because of their lumen inefficiency, standard incandescent bulbs were vilified from an environmental standpoint (source). 

This negative coverage came at a time when consumers were particularly concerned about lessening their energy consumption and thereby lessening their carbon footprint and being more green.

Another serious advantage LEDs have over incandescent bulbs is that an LED bulb’s service life can be anywhere from 3 to 25 times longer than its incandescent counterpart (source).

This would have a further environmental impact, as bulbs would need to be replaced less frequently, thus generating less waste.

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Consult An Electrician

An article such as this cannot cover all eventualities and codes that apply in all countries and all local municipalities.

For this reason, as well as for the safety of you, your family, and your home, it is best to consult with a local electrician before any type of electrical work.

When electricity is concerned, a little bit of knowledge can be deadly, and it is not worth taking the risk simply to save a little money.

Final Thoughts

Any type of electrical work should never be considered a DIY job with little basic knowledge of electrical work. Always make sure to get a professional to do any work with electricity. The number of LED lights that you can connect in any given circuit is dependent on three key factors: the amperage of your circuit breakers, the voltage of your mains supply, and the wattage of your bulbs. Once you’ve calculated that, you will have a clear idea of exactly how many bulbs your circuit will be able to power.

This opens numerous possibilities, as shown in the examples: you could easily power 20 5-watt LED bulbs on a 1 amp circuit, all the way to using 30 28-watt LED bulbs on a 5 amp circuit or even 150 on a 15-amp circuit when you really need bright lighting.

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