In an earlier contribution to this discussion,
steve wrote:

"steve" wrote in message
...
A seasonal question certainly...
As usual, dragging the xmas lights out of their box for their annual
outing - some of the bulbs are blown and the spares have long since
gone walk about. The boxes have also been chucked so can`t find what
the voltage/wattage is either :-(
How do you normally calculate what wattage/voltage bulbs to use? I
went to B&Q and had a whole host to choose from, 12v, 2.4v, 1.1W,
0.96W etc.... I`ve got three sets, one looks to be mains voltage (no
transformer), the other is low voltage (24v), but not sure what
wattage bulbs are needed. One other set is multi function, but can`t
tell if its low voltage or not . Where do I start?

Also I forgot to mention that all the manufacturers seem to have
slightly different connector sizes.
I tried some replacement bulbs I thought would be generic from B&Q
but they didn`t even bl**dy fit !

Grrr - hating xmas already
Steve

If you take a bulb out and look at it through a strong magnifying glass, it
may have the voltage and wattage stamped on it.

If a set runs off the mains - with no transformer - the bulbs are invariably
connected in series - usually either 20-off 12v bulbs or 12-off 20v bulbs.
If you divide 240 by the number of bulbs, that will tell you the voltage of
each bulb. Unfortunately, it doesn't tell you the wattage - which determines
the filament resistance. If you fit a bulb which has the wrong resistance,
the voltage won't be shared out properly across all the bulbs. If you've got
a multi-meter with a sensitive resistance measuring facility, measure the
resistance of a good bulb, and try to get a replacement with the same
resistance. [Measured cold, of course - which won't be the same as the
running resistance but should give a comparison].
--
Cheers,
Set Square
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