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:
“Can we not teach children, even as we protect them from victimization, that for them to become victimizers constitutes the greatest peril of all, specifically the sacrifice—physical or psychological—of the well-being of other people? And that destroying the life or safety of other people, through teasing, bullying, hitting or otherwise, “putting them down,” is as destructive to themselves as to their victims.”
—Lewis P. Lipsitt (20th century)
“[As teenager], the trauma of near-misses and almost- consequences usually brings us to our senses. We finally come down someplace between our parents’ safety advice, which underestimates our ability, and our own unreasonable disregard for safety, which is our childlike wish for invulnerability. Our definition of acceptable risk becomes a product of our own experience.”
—Roger Gould (20th century)
“There is no calamity which a great nation can invite which equals that which follows a supine submission to wrong and injustice and the consequent loss of national self-respect and honor, beneath which are shielded and defended a people’s safety and greatness.”
—Grover Cleveland (1837–1908)