C7 or C9 Lamp Wattage	Lamps per 15 Amp Circuit 1800 Total Watts	Lamps per 20 Amp Circuit 2400 Total Watts	Energy Savings Compared to a 10 Watt Bulb
.6 Watts - LED C7	2400 Lamps	3200 Lamps	94% Savings
1 Watt - LED C9	1440 Lamps	1920 Lamps	90% Savings
2.5 Watts - Low Energy C7	576 Lamps	768 Lamps	75% Savings
3.7 Watts - Low Energy C9	389 Lamps	519 Lamps	63% Savings
5 Watts - Traditional C7	288 Lamps	384 Lamps	50% Savings
7 Watts - Traditional C9	205 Lamps	274 Lamps	30% Savings
10 Watts - Traditional C9.	144 Lamps	192 Lamps	0% Savings

When decorating with Christmas Lights it is very important to know how many lights can be run on a single circuit. On commercial installations it is helpful to plan or add more circuits than is needed. To maximize your power and minimize you costs, we suggest that you use LED Lights or High Efficiency/Low Energy Lamps so you can run twice to nine times the number of lamps or bulbs on a single circuit. You can use the following formula to calculate total watts that can be used.

                                                         Volts X Amps = Total Watts X .8 = Useable Watts
                                                    Useable Watts / Single Lamp Wattage = Total Number of Lamps

Example: 120 Volts (the standard number used for 110 outlets) and 15 amp circuit equals a total wattage of 1800.  Since Christmas lights draw a continuous load, you should only use 80% of the total amount.  As a result, the useable watts would be 1440.  Divide the total useable watts by the watts on a single bulb to determine the number of bulbs you can run on one circuit.  Often the total number of usable bulbs is rounded off. This can be done since only 80% of the total wattage is being calculated. So, 288 lamps often will be listed as 300, and 389 as 400. 

Energy Savings

You can save on your energy bill with LED or Low Energy Lights.  To calculate your savings, you need to compare the LED or Low Energy watts to the incandescent watts.  You can use the following formula to calculate savings:

Lower Watt Bulb / Higher Watt Bulb. Change to % and Subtract from 100%  = Energy Savings

For example, if you use LED C9 Lamps, 1 watt each, instead of C9 Traditional Lamps, 7 watts each, you would divide 1 by 7 to get .14.  Change to 14%.  Subtract 14% from 100% to get 86%.  You will have a 86% total energy savings. See chart above for wattage amounts. Remember that even though LED lights are lower wattage, they are just as bright as traditional lights

Household Circuits and Finding Outlets on a Single Circuit

Most household circuits are 15 amps or 20 amps. To check the amps of a circuit, look in the circuit breaker box.  A number will be printed on the end of each switch which indicates the number of amps on that circuit. One circuit can supply electricity for several outlets. It is necessary to know how many outlets are being supplied by one circuit and which outlets are supplied by which circuit. Turn off any circuit in the breaker box and then check outlets to see which ones don't work while the circuit is off.  The circuits that don't work while the circuit is off are on that circuit.

Too Many Christmas Lights on One Circuit

If too many light stringers are connected together or if a 1000' stringer reel is left to long (1000 foot stringers are designed to be cut to the exact lengths needed, never exceeding 100 feet), it may cause the fuse to blow, the circuit breaker to pop, or the wires to overheat and lead to a fire hazard. Sometimes, if too many lights are on a single circuit, the light will work initially and then as the circuit heats up, the circuit breaker pops or a fuse blows.  Never use more than the 80% recommended watts on circuit.

Copper Wiring verses Aluminum Wiring

It should be noted that these figures apply for copper wiring only.  If the place you are decorating was built prior to the 1970s, it may have aluminum wiring, and cannot support the number of bulbs listed above.

The Number of Christmas Light Strings that Can Be Connected Together and Maximum Light String Lengths

The wire gauge used in the Christmas light line helps determines how many bulbs (or strings) can be connected on one circuit.  Ideally, you will want to use a commercial grade light string made from 18 to 22 gauge wire. The wattage of the bulb also determines how long or how many strands may  be connected together. When using C7 or C9 25-Lamp Strings, do not connect more than three strings in a series. You can connect two of our C7 or C9 100-Lamp Strings together IF you use a 3 Outlet Power Adaptor plug in between the two light strings.  You should never connect 100-Lamp Strings together without the 3 Outlet Power Adaptor plug or you could blow a fuse.

When working with our 1000 foot light string, our professional decorators recommend using LED lights and Low Energy lights to maximize your light line lengths.  They recommend cutting light strands to 100 feet to make them easy to handle, connecting no more than 3 strands together (of any length), with a maximum of 250 feet connected at any one time. If the strands are longer than 250 feet, the voltage will drop and the lights at the end of the string will dim. If you use a 3 Outlet Power Adaptor in between two 250 foot lengths, and run the power to the 3 Outlet Power Adapter, you can run 500 feet off of a single outlet, assuming you are using Low Energy or LED Bulbs.