Christmas Lights and Electrical Safety

December 1, 2015

The U.S. Fire Administration (USFA), estimates  240 home fires involving Christmas trees and another 150 home fires involving holiday lights and other decorative lighting occur each year. Together, these fires result in 21 deaths and $25.2 million in direct property damage.

For some reason, I am believed to be a Scrooge when it comes to decorating for Christmas. Normally, I let my family deal with all the  details including unpacking all the decorations, placing ornaments on the tree, getting the doggie Christmas collars out, etc. But I do serve as the pack mule in unloading the attic to get it downstairs out of the attic,  but a Scrooge I’m not!!… Ok, maybe curmudgeon.

Point One: Christmas lights in all their glory are a huge waste of energy. Four strings of C9 (old school) regular Christmas lights can consume 1800 watts of power or 1.8 kwh. On an individual house basis, it may not seem like much but add it to about 25% of all households and it works out to be a lot electricity. Not to mention, the selected idiots that adorn their house to the point that you can no longer recognize it. Ok, so you kind of get me at this point, so lets move on.

This year I am out to prove them wrong “I’M ALL IN”. In fact, it started last year. Believe it or not, I bought Christmas C7 lights (on sale) to hang outside. We’re talking outline the house type lights… This is a big step for me. So with all this lead-in, where am I headed you ask. Dont forget, this is a blog about home maintenance anyway!!

Before we go to far, let it be known what amount of lights I have installed.

  • 3 – Strings of 200 count C7 outdoor LED lights
  • Total bulbs= 600
  • Wattage per string 19.2W
  • Total waste of energy 57.6Wh
  • About the equivalent of one 60W light bulb, most of us waste that much energy on any given day

I will contain my excitement to exterior decorations and electrical load, but lets remember what the NEC code says about connected devices:

NEC 210-23  15 and 20 Amp branch circuits: …The rating of any one cord and plug connected utilization equipment shall not exceed 80% of the branch circuit rating. Furthermore… the total rating of equipment fastened in place shall not exceed 50% of the branch-circuit. In short, no one plug should exceed more than 80% of the circuit rating and that any stationary equipment (i.e. dishwashers, waste disposer) that constantly draws power should not exceed 50% of the rated circuit. Typical residential branch circuits (outlets, wall switches and fixtures) may be rated at 15 or 20 Amps.

So, we have circuit budget of roughly 1100 watts for a standard plugged outlet ((15A*120V*.8pf)*80%).

Choosing the Lights: If you dont already own exterior lights, go for  the LED versions (C7 or C9). By far, they will last the longest and cost the least to run. C7 and C9 are bigger bulbs and are easier to manage. If you take care of them, they could last a life time.

The following chart is a general guideline is fairly conservative. Most Christmas lights will provide the limitations and wattage. As mentioned in my calculation above, at 80% you have a budget of 1100 watts, at 50% your budget would be 720 watts.

C7 or C9 Lamp Wattage Lamps per Outlet Lamps per 15 Amp Circuit Lamps per 20 Amp Circuit
.6 Watts (LED) 250 Lamps(bulbs dim the farther
your runs are from main power source)
2400 Lamps 3200 Lamps
1 Watt (LED) 250 Lamps(bulbs dim the farther
your runs are from main power source)
1440 Lamps 1920 Lamps
2.5 Watts 300 Lamps 576 Lamps 768 Lamps
3.7 Watts 250 Lamps 389 Lamps 519 Lamps
5 Watts 175 Lamps 288 Lamps 384 Lamps
7 Watts 125 Lamps 205 Lamps 274 Lamps

Key Points to Christmas Light Installations:

  1. Stay within the wattage limitations mentioned; 1000W at 80% and 720W at 50%. The light packaging should provide you to total wattage. Just subtract it from your total wattage budget as you organize your lighting plan.
  2. Attempt to either use a dedicated electrical circuit  or one that does not have a lot of static or dedicated load.
  3.  Limit the string to string connection to no more than 3 or what is provided as the manufacturers recommendations.
  4. Limit the per outlet load to no more than 50% of the per circuit limitation. 80% rule: 500W. 50% rule: 360W
  5. Use timers or remote control switches to turn the lights on and off to limit the energy usage.
  6. Dont fall off the roof
  7. Merry Christmas… BOB
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