Christmas lighting can be considered a temporary electrical installation, which makes it less sturdy than permanent wiring protected by conduit. However, the temporary nature of Christmas lights does not mean that electrical safety should be compromised. Like with any other electrical device, careless use can cause a fire.
There are three main ways to minimize the fire risks of Christmas lighting. The safety recommendations provided for conventional lighting also apply in this case.
Using LED christmas lights, which have a much lower heat output.
Not connecting an excessive number of light sets in a chain.
Also consider that Christmas lights are connected to receptacles like many other appliances, and the underlying installation must be safe as well. If a power socket is unsafe, any decorative lighting connected to it will be unsafe as well.
UL Standards for Christmas Lighting
Christmas light sets are electrical products at the end of the day, and as such they are subject to industry standards. Underwriters Laboratories (UL) is a globally renowned company that offers safety certification for electrical products, and this includes Christmas lights. They are covered specifically by the UL 588 Standard for Seasonal and Holiday Decorative Products.
Lighting products that meet UL standards have already been subject to demanding laboratory tests, and the results validate their safety. If you purchase Christmas light sets that are UL Listed, you can rest assured that they have been tested by qualified professionals.
The UL 588 standard covers lighting products with an input voltage of up to 120 V, which are intended for temporary usage of up to 90 days. It is important to note that the standard not only covers light sets, but also decoratives with Christmas shapes that use one or more lights - the stars commonly used for the top of Christmas trees are a good example.
Safety Advantages of LED Christmas Lights
LED Christmas lights have significant advantages over incandescent products. First of all, they consume around 80% less electricity, which translates into power bill savings during the Holiday season. LED lights are also less likely to start a fire due to their reduced heat output, and their lower current reduces the chance of wire overheating.
However, be careful when using both LED and incandescent Christmas lights. If you connect an incandescent light set to the end of an LED set, the current through the LED set will now be the sum of both, and this keeps adding up as more light sets are connected together.
Another safety advantage of LED Christmas lights is that burns are unlikely when they are touched by accident. On the other hand, incandescent Christmas lights can get very hot with extended operation. Consider that Christmas lights are installed in places that are easily accessible, while conventional light fixtures are often out of reach.
Safety Considerations when Connecting Light Sets Together
As previously described, connecting multiple Christmas light sets adds their current. Each light set carries it own current plus that of all lights connected downstream.
For example, if you connect five light sets together, the first one carries the total current.
The 3rd light set carries its own current, plus the current of sets #4 and #5.
The maximum number of light sets that can be connected together is normally provided by the manufacturer. As you might expect, LED lighting allows longer connections because the wattage of each light is five times smaller. When the number of consecutive light sets allowed by a manufacturer is exceeded, the wiring of the first set will tend to overheat and melt. This exposes the conductors, eventually causing a short circuit or line fault.
An excessive number of Christmas lights chained together is dangerous even when using LED products that meet the UL 588 standard. The installation should follow the instructions provided by manufacturers.
Christmas lights that are not recognized by UL may have a lower price than their listed counterparts, and incandescent light sets are cheaper than LED versions. However, in this case the low-cost option comes with significant limitations: a higher operating cost, a shorter service life, and increased fire risk.
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