Why are strings of Christmas lights so unreliable? Why aren’t strands made so that a single light can go out and the rest stay on no problem?
In: Engineering
? That’s what mine do. If one bulb goes out, the rest stay on. Prob just the brand you got.
Most Christmas lights are wired in parralel exactly so that if one goes out the rest will stay in. Either the entire wire broke inside the strand that won’t allow it to transmit electricity or you got jank ass Christmas lights.
Technically all lights should have been wired in parallel after 1995(because of a lot of fatal fires) But a lot of cheap strands still wire them in series to save money. Parallel strands should only have one light go out to make it easy to maintain. Somewhere on the box it should say parallel cirquit.
Most Christmas lights are made up of multiple strings of lights in a series, which means that the electricity flows through one bulb then goes through the next an so on. If one of bulbs goes out it’s like cutting the wire between them there’s no path for the electricity to flow.
Usually the only ones wired in series like that are cheap mini ones. Your common C7 or C9 size are always parallel that I’ve seen.
It’s actually a bit tricky to do with a string that has the LEDs or light bulbs wired in series.
One broken light will interrupt the power to all others, so if you want the string to continue working, you need to provide a path for the current to flow despite the broken light. A bypass basically.
The problem is that when there’s a bypass in place, the electricity would simply take the path of least resistance (through the bypass) and the light wouldn’t illuminate, even though it’s still working. So you need a special kind of bypass that only works when the bulb is broken. There’s a special type of diode called Zener diode which can be used to do that, but that obviously adds cost and makes the string more complicated to manufacture.
The other solution would be to wire the lights in parallel, but that’s not a great solution for LED strings since it can result in uneven brightness, and it’s more costly because a parallel circuit requires two wires instead of just one.
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