UK source of filament lamps?

Apparently its become illegal to sell the higher wattages anymore - try ebay and/or various other mail order sources.

The vast majority of failures occur at switch on due to the surge current at that instant, some TVs, monitors and other switch mode power supplies have a negative temperature coefficient thermistor in series with the fuse to limit turn on surge - a salvaged NTC thermistor grafted into behind the switch plate with an insulated connector block will substantially increase the life expectancy of filament bulbs.

No it won't. A worn out filament may well fail during a turn on surge.

Avoiding the surge can only delay the inevitable for a short time.

A significant life expectancy increase can only come from avoiding something that wears out the filament and turn on surges don't.

You're neglecting the effect of the small volt drop that sustains the NTC in a heated state, published curves clearly show that underrunning filament bulbs by even a small amount gives a significant increase in life expectancy.

The combined effect of that and almost completely eliminating the turn on surge is very significant - I know for a fact, I've tried it.

Urrm, a very well informed source has told me 2 weeks ago that they are no longer marketed as light bulbs but as "heating elements". Seriously. I'm not making this up.

Maybe you start looking for heating elements with an E17 thread.

Hope it helps

Werner Dahn

Most UK houshold lightbulbs have bayonet caps.