The Griswold Family Christmas Lights: Questions Answered!

One of the most iconic holiday movie scenes of all time occurs when Clark Griswold finally succeeds in lighting the family Christmas lights: all 25,000 of them (not counting the Santa, the eight tiny reindeer, and the “Merry Christmas” sign).  Once lit, the Griswold house in National Lampoon’s Christmas Vacation is so bright that the lights actually blind the neighbors.  Now, clearly this is a comedy with a lot of exaggeration involved, but even so, energy nerds like us at YourEnergyBlog can’t help but ask: how much energy was Clark really using, and what would it cost to light that house?

If you need a refresher on the scene from this classic holiday hit, we have you covered.



How much electricity were the Griswolds really using with those lights?

One 100-count string of incandescent lights uses about 40 watts of electricity.  Griswold (appropriately nicknamed “Sparky” by his wife) proudly announces that he has strung 250 of them around the house for a total of 25,000 bulbs.  So, 250 strings of (today’s) 100-count lights use approximately 10,000 watts, or 10 kilowatts (kW).  To provide some context: an average suburban household uses about 1 kW in a month.  Clark put ten times that amount of electricity demand on the grid instantly . . . just from his house. Image courtesy of Fanpop.com

That kind of usage might make the Griswolds’ electric meter spin at a breakneck pace,  but it probably wouldn’t require the local utility to fire up its auxiliary nuclear supply, like it does in the movie. In today’s neighborhoods, demand response programs might eliminate the need for peaking power plants.


What would this cost today?

Lighting an entire house to this extent with incandescent “twinkle lights” can’t be cheap.  Two hundred and fifty strands of them would have an upfront cost of about $3750 alone! Using today’s average energy prices in the US, 10kWh of electric use would set Clark back about $1.19 per hour – a hefty electric bill if he keeps those lights on too long.  Eight hours would cost him $9.52, so that’s basically an extra ten dollars per day to keep the house lit.  Keeping it lit eight hours a day for the entire month of December would mean an extra $295.12 on his energy bill.

Today, Clark might opt for strands of LED or light emitting diode lights.  A comparable 100-count string of outdoor LED lights boasts 85 percent reduction in energy consumption compared to incandescent lights. It’s true, the LED strands will cost a bit more. At around $15 per strand, the upfront costs of 100 strands is about $5000. But, one string of lights only uses about six watts compared to the incandescent’s 40 watts. All together, the Griswold house would be using a mere 1,500 watts of demand, or 1.5 kW.  Over time, lighting the Griswold house with LED lights would cost only about $1.50 per day. That’s a savings of $248.62 over the course of one month. Consider the fact that those LED lights will keep the house festive for several years, and there’s big savings in investing in those bulbs.

So, while you (hopefully) don’t plan on using enough lights this year to black-out the neighborhood, incandescent lights are clearly not easy on your holiday budget.  Opt for LEDs. They might cost a bit more at the register, but they will give you the gift of energy savings year after year. Happy holidays, everyone!

Jessica can be found on Twitter and Google+.

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  • Sue

    I redid the math on your figures, 10,000 watts divided by 120 Volts is 83.3 amps, that would get a good spin on an old meter. It would not require the power company to beef up the output but it was funny to see it. Now you assume that Clark used the standard mini’s the wattage output would have to be much higher to produce the light output that you see. So first find out what was used before you create an inaccurate statement.

    • Matt

      The string of lights(big knot of lights) he pulls out of the box and hands to Russ, are C7 bulbs (those that are not missing). You an also see the bulb size in the scene when Clark pops his head out of the attic to see the others drive off down the road. Standard C7 bulbs draw ~5W at 120VAC. C9’s draw about 7W. They are one of those two types and definitely not miniature lights like the common ones used today. Miniature bulbs do not have screw in type sockets. 125kW is a tiny amount for the utility and would not even register on their overall power meters. At best, Clark would have blown the 20A (or less) breaker that he plugged all of the strings into, lol!

  • Matt

    Your article is interesting but the numbers are a bit off. The bulbs used on the Griswold house are C7 bulbs and draw about 5 Watts each. 25,000 bulbs would draw 125kW which a normal residential service can’t provide. At $0.10 per kW-h, it would cost $12.50 per hour to keep all those lights on.

  • Jessica Kennedy

    Thanks to everyone for the great information! Yes I agree they must be C-7 or C-9 bulbs. Today a person decorating like that would likely use the average strand we see sold everywhere, so I did make assumptions based on that. It’s rare to find those old bulbs these days. There are LED versions available though – so he might use those. It still would save energy over the incandescent lights!

  • http://www.yourenergyblog.com/ Jessica Kennedy

    Keep in mind these are just estimates! The real cost of running those lights could be even higher! Even if my estimates are a bit high, that’s a lot of money to spend on twinkle lights! I’d rather put up a nice wreath and spend the money on extra presents.