Safety
Any set should be unplugged before repairing. If a set has no transformer, it is not line isolated. The small matchbox-sized electronic controllers do not have transformers in them, and sets with such controllers are also not line isolated, as well as all parts inside the controllers.
The number of strands of continuous light sets that may be safely daisy-chained in sequence varies based on whether the lights are LEDs, ordinary miniature light bulbs, or the larger C7/C9 type light bulbs. Other factors include the voltage of the set and the size of the wiring in the set. Those with questions should consult the manufacturer's instructions or an electrician.
Most light sets come with built in fuses to help protect against overheating and to prevent household fuses or circuit breakers from being tripped. If a fuse blows, the strand must be unplugged and the number of strands must be reduced. If the strand has nothing attached, or has blown repeatedly, it may contain a short circuit and should be repaired or discarded.
Hobbyists who don't want to discard a damaged set can cut it into many individual bulbs, each of which can be powered by a safe low voltage source. These bulbs can be used in projects such as microcontroller or PC controlled animated displays. The AC power plugs are usually crimped and molded on, however, and cannot be safely re-used.
Some fiber optic sets may use halogen bulbs in their bases, in such cases, all precautions related to this type of bulbs should be observed.
Animated sets should not be watched by people having photosensitive epilepsy. Non-animated sets exist and can be used in such cases.
An episode of the show MythBusters covered the possible fire danger from Christmas lights.
As with most electrical devices bare wires are a sign the string should be discarded, and avoid overloading individual cords.
Read more about this topic: Christmas Lighting Technology
Famous quotes containing the word safety:
“Love no man in good earnest, nor no further in sport
neither, than with safety of a pure blush thou mayst in
honor come off again.”
—William Shakespeare (1564–1616)
“He had a gentleman-like frankness in his behaviour, and as a great point of honour as a minister can have, especially a minister at the head of the treasury, where numberless sturdy and insatiable beggars of condition apply, who cannot all be gratified, nor all with safety be refused.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)
“The Declaration [of Independence] was not a protest against government, but against the excess of government. It prescribed the proper role of government, to secure the rights of individuals and to effect their safety and happiness. In modern society, no individual can do this alone. So government is not a necessary evil but a necessary good.”
—Gerald R. Ford (b. 1913)