I emerged from my shower on Saturday, and plumped down in a despondent heap to contemplate the fiasco-in-progress that the New Bog plumbing had become. Turning to Mrs Stevie I noticed that she wasn't, for once, in a homicidal mood but looked on the brink of tears. What on earth could be the matter? I initiated contact1 with a jaunty "Wassamarrer?"
It turned out that while I was struggling with the arcane science of pipe-weaving, Mrs Stevie had deployed her beloved Self-Illuminated Christmas Bush O' Merriment and had discovered that about 25 of the 300 or so bulbs were dark. Heaving a sigh I took a look. All the plugs seemed to be in place in a nice little cluster inside the tree. I took a feel. All the plugs were in tight. "This not look good" said Mr Brain.
Strings of Xmas lights tend to be made as multiple strings of so many bulbs strung end-to-end with a single plug. 100 light will be 2 strings of 50. 50 can be a single string, but it isn’t unusual to find them as two strings of 25. It really depends on what the manufacturer makes as set units, and whether these units can be wired as a longer string economically. More money is required to make a string as two strings of 50 rather than one of 100 for example, but the advantage is that only half a string in in jeopardy at any one time if a bulb goes. My money was riding on these 25 bulbs being one half of an otherwise fine string of 50.
Now we all know the myth that when bulbs blow they are supposed to short out so the rest of the string keeps burning bright and summoning Santa. Indeed, most boxes of light carry stern warnings about not letting things get out of hand when the bulbs blow, because too many blown bulbs in a string will cause a cascade of blowing bulbs as the available voltage is shared by fewer and fewer increasingly overpowered bulbs. I've actually seen this happen. Once in 50 years.
The bulbs are designed with a springy metal strip that is attached to the filament at one end. The filament holds the metal strip back and prevents it springing forward and bridging the gap, shorting out the bulb. When the filament blows, the metal strip is released and like a switch reconnects the bulb internally so that power can flow through it to the rest of the string. The problem is that the older the bulbs are, the longer the heat has had to work on the metal strip, annealing it so that when the filament breaks the metal doesn't make it all the way across the gap. Lights out.
I used to have a tool the manufacturer claimed could sense the A/C standing wave in the bulbs and tell which one was blown. It rarely worked, had a complex set-up and didn't work at all on multi-string, er, strings. I lost the instructions for it long ago, and I lost the tool itself about five years back so there would be nothing for it but to do things the hard way.
This involves taking a bulb out of a working string, then removing each bulb from the bad string in turn and plugging it into the good string to see if it works or not. Using this method (accurately referred to as a brute force search) you hope that the broken bulb is near to where you start your search, that there is only one or possibly two or three bulbs blown and that you don't blow the good string by repeatedly flashing it on and off as you test.
Over the course of about an hour I made my way around the tree testing each bulb. Some of the bulbs had been hidden very cleverly by the fiendish tree manufacturer, and the bulbs had nasty little latches on them that began to hurt my hand each time I opened one. Not only that, some sort of machine able to exert a force of several tons per square inch had been employed to drive the bulbs into their sockets, making them all but impossible to remove without levers. Eventually I reached the end of the string without provoking it to resume illumination and so was forced to admit defeat.
Such was my despondency at that point I simply went to bed.
- It is a measure of my own state of mind that I took none of the precautions that 18 years living with that harridan have drilled into me, such as "don't" or "take cover first" ↑