Basics About Christmas Lights Power Usage

Basics About Christmas Lights Power Usage

A typical household circuit may include multiple outlets, interior lighting, or built-in appliances that are all on the same circuit. This means that whenever you plug your Christmas lights into the wall, they are sharing the capacity of that circuit with other appliances that may be drawing power. If there are few things on the circuit, you will have more wattage capacity to work with. However, if your circuit already has many things drawing power from it, you may start to "trip" the breakers in your fuse box. This happens when your wattage exceeds the amperage capacity of the circuit.

Some notes about household circuits:

Most household circuits draw 15 or 20 amps

It is recommended that all circuits do not exceed 80% of their maximum wattage capacity

A 15 amp circuit supports 1,800 watts (80% capacity is 1,440 watts maximum)

A 20 amp circuit supports 2,400 watts (80% capacity is 1,920 watts maximum)

How do wattage and amperage relate?

A watt is a unit of energy. Amperes are a unit of electrical current. Amperage refers to the total amperes that can be supported.

The amperage of a light string determines how many bulbs can be used in one cord. This usually applies when the string and C7 or C9 bulbs are sold separately and the lights are customizable. All of Christmas Lights, Etc's light strings and spools have amperages listed in the product specifications.

The amperage of a household circuit determines the total wattage that can be drawn from the entire circuit, regardless of how many outlets the circuit contains. Outlets connected to a single circuit share the amperage of that circuit, so be sure to account for other devices running on the same circuit, such as lights, electronics, or appliances. Keeping the amperage of a circuit within 80% ensures that the circuit breaker will not trip.

How to Calculate Total Amperage

When using a Christmas light string that has the bulbs hardwired into the outlet or screwed into the outlet, the total amperage is usually listed near the total wattage on the UL label.

When the total amperage is not provided, calculate the total wattage first, then the amperes.

Calculate the total wattage by multiplying the wattage of each bulb by the number of bulbs in a string

Calculate the amperage by dividing the total wattage by 120 volts (US household outlets run at 120 volts)

How many strings can you string end to end?

Strings come in many styles and lengths. The more lights you have on a string, the more power it uses. Christmas strings often have plugs at the end to allow for more strings to be connected. Traditional incandescent mini strings are usually limited in the number of connections you can make. Depending on the number of strings, you can only connect 5 to 10 strings at most. This limitation has historically made outdoor light displays difficult for the average homeowner because it requires a lot of extra outlets and extension cords. However, LED strings use very little power compared to incandescents, so you can string up to 40 strings end to end, depending on the string specifications. And, some LED strings use even less power, allowing you to string up to 90 strings end to end. While the number of strings that can be connected varies by product and manufacturer specifications, LED string lights allow people to make great outdoor displays because more strings can be used more easily.

One more thing…if your display is very large or you plan on using all incandescent lights, we recommend taking some time to calculate the power needs for your entire display by visiting the Christmas light wattage and power resources linked below.