Mark Lloyd wrote:
On 29 Nov 2006 05:51:21 -0800, "terry"
wrote:


ukwildcatfan wrote:
I have a quandry and would like some help on this matter. I need to
shorten christmas light strings to fit certain decorations but have no
idea how this is done. What I am using are the mini light sets with plugs
on both ends. Cutting the end off is not a problem. That is pretty
straight forward. I just need to shorten the length.

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Reading other posts;
.
We all seem to be assuming that the lights are those series strings.

But OP mentions "Plugs at both ends". In other words the input voltage
goes right to the far end so another set can be plugged in beyond it.

That suggests the light strings may 'not' be the type where all the
bulbs are in series and if one goes pop they all go out?


They are series. I included a wiring diagram of a typical string in
another post. There will be hot and neutral wires running straight
between the ends. The series of bulbs is connected to hot at one end
and neutral at the other. Fuses are in the male end.

But a word of warning some types have at least three wires and while
the bulbs are in series the input voltage is also carried to the far
end. Some of the 'hanging icicle type lights' seem to be of that type?

As well as most ordinary miniature light strings. Note that 2-series
are common. You will notice a point in the middle of the string where
only 2 wires are present. That's the point between the series. Icicle
lights often have 2 such points, since there are 3 series.

Tracing for dead bulbs in those, for my neighbour, last year, was a
nightmare!


It helps a LOT to use one of those $5 testers (that sense 120V across
a bulb, which happens only if it's bad).

OK you sound like you have a pretty good handle on how these work.
What I want to know is, if they're in series (which sounds right since
if you remove a bulb, the whole string or whole section goes out) how
come if one burns out, the rest stay lit? (Which they advertise on the
box.) -- H