Calculating Amps for Christmas Lights


      Probably the single most important part of any lighting job is knowing what your power needs are and what limitations the products you have are. All Christmas lights and any holiday or event lighting products have limits and knowing just how much power your light strings can handle is how you can save yourself hours of trouble down the road. We try our best to provide all the product specs that are available to us and knowing things like light strings wattage, volts, amps, etc lets you fully prepare for any decorating job.

What you need to know:
  • Bulb Wattage
  • Wire Gauge/Amps Rating
  • Amperage of Fuses in plugs (if applicable)
  • Total number of bulbs
  • The length of wire you need
  • The amount of power available
Common Christmas Light Bulb Wattage:
  • C7 bulbs - 5 Watts
  • C9 bulbs - 7 Watts
  • LED Screw In Bulbs - .96 Watts
  • Mini Lights - Varies .4 to .96 watts
  • LED Light Strings - Approx. .096 watts
     Below is formula you can use for calculating the amount of amps from bulb wattage. This will give you valuable information for 2 things, how much power your lights will require and how many lights you can run continuously before needing to start a new string. For C7 and C9 light strings (which applies to screw in LED bulbs) the wire can handle 7 or 10 amps depending on the wires insulation rating, knowing all this lets you maximize the number of bulbs per strings. To do the math on calculating amps for Christmas lights you need to know your bulb wattage and the number of bulbs you have. That will give you your total wattage. Once you have the total wattage you can divide that number by 110 and that will give you your number of amps used.

(Bulb Wattage) x (Number of Bulbs) = Total Wattage, (Total Wattage) ÷ 110 (Volts) = Amps
Example:
5 Bulb Wattage x 100 Bulbs = 500 Watts, 500 Watts ÷ 110 Volts = 4.55 Amps