xmas lights voltage/wattage

[steve]

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?

Steve

[steve]

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

[Set Square]

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].

[Nick Smith]

Had this problem myself last week - What I did with my 40 bulb (6 volt bulbs) set was to take a small sample, say 3 bulbs, run each of them of a variable bench supply at an accurate 6 volts (measured at the bulb) and with an ammeter in series and measure what the current being drawn is. Mine were all about 125 mA, which also gives the wattage by calculation. Be careful not to measure the fuse bulb, and be sure to have one in circuit to avoid the domino effect.

Then a trip down to the shed armed with this electrical info to see what the bases look like and the choice is made. Our Tesco had a good selection of spares (99p for 5).

Alternatively there is an (expensive) website,

which has an online catalogue if you know the part number (usually on the box).

Nick

[N. Thornton]

Hi

For old mains sets,

20 bulbs --> 12v 1w 40 bulbs --> 6v 1w

I dont know what you mean by multifunctional, but it if does tricks it'll be low voltage. For unknown low voltages, just start with the highest V rating of bulb, replacing it with the next lower voltage till it lights properly.

Regards, NT

[PJO]

Why "Xmas" not "Christmas"?

Why are some people so damn lazy when writing words?!

[Dave Plowman]

Damnably or damned. Either you accept the colloquial use of language here or you don't.

[Terry D]

I quote from the The American Heritage® Dictionary of the English Language: Fourth Edition, 2000:

SYLLABICATION: X·mas

PRONUNCIATION: krsms, ksms

NOUN: Christmas.

ETYMOLOGY: From X, the Greek letter chi, first letter of Greek Khrstos, Christ. See Christ.

USAGE NOTE: Xmas has been used for hundreds of years in religious writing, where the X represents a Greek chi, the first letter of , ?Christ.? In this use it is parallel to other forms like Xtian, ?Christian.? But people unaware of the Greek origin of this X often mistakenly interpret Xmas as an informal shortening pronounced (ksms). Many therefore frown upon the term Xmas because it seems to them a commercial convenience that omits Christ from Christmas.

Terry D.

[PJO]

I consider myself told and informed.

I strongly suspect though that many people using Xmas are also unaware of the Greek origin of the X and use Xmas as a commercial convenience that omits Christ from Christmas !!

I'm sure you'd agree Terry?

[Dave Liquorice]

And me.

And I bet most pronouce it ex-mas as well. Still hate the term and avoid using it.

[geoff]

In message , Terry D writes

Which is all it is really

[geoff]

In message , PJO writes

What does it matter?

I take it you're not a serial text messager then

[Terry D]

Agreed :-)

Terry D.

[Brendan DJ Murphy]

I still cant seem to find replacement bulb for my multi-function Christmas-tree bulbs.

Naturally, the original box and instructions have long been thrown away. There is a label stuck around the wire saying " replacement bulb: 7volt 8.4watt"

Is there any look-up table to convert this to one of the new codes "eg: w5" which appear to be the new way bulbs are identified?

Brendan