Why do xmas tree lights partially go out?

Question

Part of the strand is on and part of the strand is out and how do you repair this?

Answer 1

In the business we don't waste time and simply throw them out. You know,... the labour versus cost thingy. But at home it drives me crazy! I used to think it was a broken wire somewhere assumming it couldn't possibly be the old burnt bulb problem. More recently I hear that it still could be due to a burnt bulb! My theory is that the third wire they brag about on the box that is supposed to complete the circuit (even when a bulb burns) is not wired correctly. When you reach the point where the third wire should be connecting to the next light, I sometimes notice the wire skips a few places which would break the circuit. So in essence it's still a burnt bulb problem or a broken wire in the bulb or a poor connection from the bulb to the socket. The fun part is finding it. They sell testers.

Answer 2

You have to get a known good replacement bulb and replace each bulb one by one until you find the bad one (when you put the good bulb in the socket that held the bad bulb, all the lights will come on again). If there are two bad bulbs, though, you'll probably never find the bad ones unless you replace every bulb with a known good one. In that case, it's probably better to replace the strand.

Longer strands of lights (especially the tiny ones) usually have two runs of lights in series and a couple of series in parallel.

Series means that the electricity starts at the source (the plug) and goes through the first bulb, then to the second, then to the third, and so on until it reaches the last bulb. Then the wire is brought back to the other side of the source to complete the circuit. If any one bulb is removed or goes out, that breaks the circuit and all of the bulbs in that series go out.

Parallel means that each bulb is connected to both sides of the source. That way, if one bulb goes out, the circuit is not interrupted to any of the other bulbs and they stay on. In this case, they put a couple of runs of series-connected bulbs in parallel, so that if one series of bulbs goes out, it won't turn off all the bulbs in the strand.

The reason they run groups of lights in series instead of running them all in parallel is that lights in a series circuit have a cumulative amount of resistance to the current (the resistance that each bulb has is added together). This limits the amount of current that runs through each strand.

If all of the bulbs were in parallel, the amount of resistance would be so small that a huge amount of current would be generated at the plug. This would require very heavy-duty wiring or bulbs with more resistance to prevent overheating of the wires.

If you notice, bigger outside house light strands do not all go out when one bulb goes bad or is removed. That's because the larger bulbs have bigger filaments with many more turns, which offers more resistance (actually impedance, which is kind of resistance to AC current) to the source current and they can be connected in parallel without causing excessive current. But, those mini lights are too small to build to where they can handle that kind of current capacity at 120 volts AC.

Answer 3

You have to find the bulb that is blown and replace it. It's a tedious process but it's not hard. Just look at the wire inside the bulb and see if its broken. If it is, replace it. It's probably going to be close where the darkness begins...good luck.

Answer 4

I am certain it is part of a coalition that wants us to buy new lights at least every 2 years. I usually just give in and buy a new string. Less headaches, and I don't have to hear my children chanting, "We Want The Tree!!!"

Answer 5

Because some lights are wired in series and if one goes out they all do. Save your self a lot of problems and only buy lights wired paralell.

Answer 6

Make sure each little bulb is screwed in all the way.