Reuben's Home Inspection Blog

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Christmas Lights – What Would It Take To Start A Fire?

 

There’s a ton of web sites out there offering all the same basic advice on Christmas light safety; don’t use frayed cords, don’t use damaged lights, blah blah blah.  I think most people know all this stuff.  I was curious what could really pose a threat if you’re using new lights and new extension cords, so I thought I’d do a little math and figure it out.

As they say on the greatest TV show ever, WARNING: SCIENCE CONTENT.

As I see it, there are three main places for potential failure when installing Christmas lights – extension cords, power strips, and light cords.  I’m assuming the lights will be plugged in to a standard 15 amp outlet, and nothing else is running on that circuit (lighting, TVs, radial arm saws, etc).

Lights: I took a brand new string of 150 lights and examined the fine print on the warning label.  As you can see, the lights draw .54 amps.  This means that you could theoretically have 27 sets of lights plugged in to one circuit, and you would use 14.58 amps – just below the tripping point of a standard 15 amp breaker.  Each string of lights has a 3 amp fuse built in to the plug, so you could potentially have five strings of lights plugged in to each other, end to end, to get 2.7 amps.  For the record though, I’ve always heard that you shouldn’t use more than three.

Warning Label with Arrow
If you noticed the date code on the lights, you got me. These lights have been sitting in my basement for seven years. When stuff goes on clearance for 25 cents, I can't help myself!

Christmas Light Package

Power Strip: I just took a look at a cheap power strip that I had lying around in my basement, and was surprised to see that the power strip was rated for 15 amps!  This means that the power strip should be able to deal with anything I plug in to it – if I overload it, the circuit breaker in my electric panel will trip.

Extension cord: I expected this to be the weakest link, but it’s not as weak as I thought; the smallest extension cord I could find online or in the store was rated for 13 amps.  This means that if you plugged a power strip in to the end of the extension cord and ran 5 strings of lights (with 5 sets to a string), you would have a total of 25 sets pulling13.5 amps.  This could start the extension cord on fire.  Twenty-four sets of lights would probably be safe at 12.96 amps, giving you a total of 3,600 lights.
Extension Cord

The bottom line? All the blah blah blah advice you hear is right on.   As long as you’re using new lights, new extension cords and new power strips, you shouldn’t have much to worry about, and you shouldn’t have to do any math.    Just remember to read the safety labels, and do some simple calculations if you think you're using too many lights.

What if 3,600 lights isn't enough? Of course, a lot of people ask me this, and I always tell them to buy LED lights.  They're hideously expensive, but they use 80% - 90% less power.

What about the heat from the lights? Mythbusters already tried setting a Christmas tree on fire using only the heat from the bulbs.  It's impossible.  They ended up using a neon transformer to set a tree on fire.

Reuben Saltzman, Structure Tech Home Inspections – Email – Minnesota Home Inspections

Reuben Saltzman, Structure Tech Home Inspections

        

Comment balloon 18 commentsReuben Saltzman • November 26 2009 07:40AM

Comments

Reuben, the only job I can think of that would be as much fun as being a home inspector would have to be Myth Busters:)  Have a great Turkey day Reuben

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 8 years ago

We have friends who had to have the power company come out and approve more electricity coming into their home because of holiday lights --  good post -- be careful out there with the lights.

Posted by Bob & Carolin Benjamin, East Phoenix Arizona Homes (Benjamin Realty LLC) over 8 years ago

Good post Reuben,

My strongest area of home inspections is electricity.  The most dangerous electical issue is a bad connection.  Each on of those strings of lights that are connected together along with each bulb connection and the extension cord connections each have potential to generate a lot of heat if there is a poor connection.  It is best not to use lights or extension cords that are loose fitting or have any sign of melting, etc.

Posted by Ralph Brady, The premier inspector in Humboldt (Brady Home Inspection) over 8 years ago

Charles - yeah, I dream about getting a job on that show.

Bob & Carolin - wow, those are some die-hard Christmas light fans!

Ralph - Good points.  Loose connections are bad news.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 8 years ago

With 3,600 lights the space shuttle should be able to see me just before I turn into ash.

Posted by Gene Allen, Realty Consultant for Cary Real Estate (Fathom Realty) over 8 years ago

Where is the UL listing on those Made in China lights?

Posted by Mike Parks, Inspector (Residential Building Inspectors) over 8 years ago

Gene - yeah, I was kind of making a joke about that.  That's ridiculous!

Mke - see below.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 8 years ago

OMG please never let me live next to the person with all those light decorations on the outside of their house!  LOL

 

Posted by Debbie Walsh, Hudson Valley NY Real Estate 845.283-3036 (Shahar Management) over 8 years ago

Debra - I'm picturing a scene from National Lampoon's Christmas Vacation, where the neighbors had to pull down their shades :)

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 8 years ago

Mythbusters is a great show. Those guys have one of the best jobs ever! I remember the Christmas tree light episode as well.

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 8 years ago

Well I must admit I usually put up so many lights (no number count). This year I have decide to cut to a minimun. I would also have everything done by this Sat and haven't put one thing up yet this year. Thanks for the post.

Posted by Monique Hailer, South West Florida & Southern Maryland Homes (Schooner Bay Realty., Inc. & CENTURY 21 New Millenniun) over 8 years ago

Getting ready to decorate and these are timely tips!  Thanks for posting them!

Posted by Delete Acct Desert Communities over 8 years ago

That is EXACTLY what I was picturing!  So much light you wouldn't be able to sleep at night!  LOL

  

Posted by Debbie Walsh, Hudson Valley NY Real Estate 845.283-3036 (Shahar Management) over 8 years ago

James - Dream job, huh?

Monique - thinking about LEDs?

Laxson - no fires this year.

Debra - what a classic scene.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 8 years ago

I went with some LED this year.  I'm with you on the rule of thumb not to string more than 3 of the "old" style lights together.  But LEDs are different.  The lights I bought this year were the Icicle type...each string is 9 foot long.  The box said you can put 17 strings togother!!

Posted by Chuck Capan, REALTOR Licensed In IL. - Moline Homes Quad Citie (REMAX River Cities) over 8 years ago

Chuck - how do you like them?  Any problems with your garage door opener?  I installed LED floodlights at my garage, and the light they give out disrupts the auto-reverse sensors at my garage door opener.  Now my door won't close if my LED floodlights are on!

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 8 years ago

They goof up your sensors? That is odd!  I kind of like the LCD lights.  Theyare different though.  More like a 6400K light (blueish in color) instead the warmer color of the "old" style.

Maybe you could install a "shield" over the sensor to put the eye in the "shade".  Like a cardboard tube from paper towels.

Posted by Chuck Capan, REALTOR Licensed In IL. - Moline Homes Quad Citie (REMAX River Cities) over 8 years ago

Chuck - I meant to install some type of shield, but never thought of the cardboard tube.  Great idea!  I'll let you know how it works.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 8 years ago

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