This comes up fairly regularly,so out of interest I have copied some information about the reasons and possible solutions
I was aware that 2-way switching wired via 2 strappers could cause this problem
below is some info I found,as yet i cant find a supplier
A CFL may flash occasionally when off if the switch wire run is especially long.
In exceptional cases a CFL will flash occasionally when switched off. This is due to wiring capacitance passing a tiny current, which gradually charges the CFL's reservoir capacitor, and after a while it attmpts to start, giving a momentary flicker.
2 conditions tend to cause this:
an especially long switch run
supply switched on the neutral instead of live pole
If a filament lamp is on the the same switch (or PIR/ timer) as the flickering CFL, the problem will not occur. The filament lamp can be a low power type, such as 15w.
Resistor
It is also possible to stop the problem by fitting a suitable resistor in parallel with the bulbholder. Use either:
- A 270k to 470k 400v rated resistor, or
- 2x 150k to 220k 200v rated resistors in series, with both the same resistance value.
Resistor choice explained:
A capacitor can be used in the same way as a resistor. These should not be fitted inside the lampholder itself for temperature reasons. Capacitors consume no power.
A 10nF 275vac capacitor with X2 dielectric is suitable.
Note that capacitors marked as 250v rated are totally unsuitable for mains use. Before the advent of X & Y capacitor classifications, 600vdc caps were often used on unfiltered mains, but this is no longer compliant.
A 270k resistor will dissipate 0.2w on 240v mains.
2 way switch
R1
o---/\/\--- Neutral
switched live line to lamp ----o---
o------ Live
No-flash variation
R1 is a single 270k resistor rated to 400v, or 2 identical 150k 1/4w resistors in series.
