Hiya

I've got a 23 watt PHILIPS MASTER PL energy saver bulb which I use in my bedroom light that has been working for months as I got it from late 2013 off the internet. However when its switched off, its ballast makes a quiet continuous rattling click like sound. But when you switch it on the ballast stops making this noise and is silent 

Its been like this with that bulb since its installation in late 2013. If anyone knows why my bulb does that, I'd be interested to hear

Regards

Flurofan96

The problem is not the bulb, but your electrical installation. The bulb get small current from the mains, which charges the internal capacitor and once the voltage reaches ~30V (trigger voltage of the startup diac) the inverter starts oscillating. But that mean it start to draw current from the capacitor, so the capacitor get quickly discharged and that stops the inverter again. And this cycle makes one click.
Now as the inverter stops, the small current starts to charge the capacitor again, the cycle repeats, so do the clicks, so the rattling noise.

The leakage may came from two origins:
Either it is a consequence of the installation design. It could be the wire layout is such, it forms large capacitance between permanent line voltage and the feed to the socket, so across the switch. This is typical for installations with multiple switches controlling single circuit (stairs, corridors,...).
Or there belong a working current of an eventual glow pilot lamp usually connected across the switch (to mark it's position) or an idle supply current of an electronic switch. Normally the incandescent short this leakage out, so the circuit is OFF.

If this is not your case (the wire with permanent phase does not go along the switched wire to the lamp), you may have an insulation problem (leakage) in the switch. This second cause is then very dangerous: It will deteriorate and at one moment it will locally overheat and in that way it may cause a fire.

So you should first check, whether it isn't caused by the fault, so there are conditions to form the leakage as a result of the design (so it is safe by itself and so only the lamp has to be treated).
Then the usually successful treatment is to connect an X-rated (for your mains voltage) capacitor of few 100's nF across the lamp socket terminals, so it bleed that leakage without creating sufficient voltage for the lamp electronic to start (and to not form any power dissipation when the lamp is ON)

Yes, I agree.
I had the same problem caused by a lighted wall switch! The little neon glow bulb allowed enough current to flow causing the problem.
When I was a kid, my room had an old mercury type wall switch that caused some leakage too.

That reminds me why it is a bad idea to even think about dimmable LED on my bedroom dimmer. When the light is on the dial is illuminated on the dimmer, when the light is off both the dial and an additional guide light strip (extra part, but I put in in just in case the dial didn't illuminate when off) and those LED circuits would cause this type of leakage. Better get some 53 watt or 72 watt GLS halogens for the light level upgrade instead.

That reminds me why it is a bad idea to even think about dimmable LED on my bedroom dimmer. When the light is on the dial is illuminated on the dimmer, when the light is off both the dial and an additional guide light strip (extra part, but I put in in just in case the dial didn't illuminate when off) and those LED circuits would cause this type of leakage. Better get some 53 watt or 72 watt GLS halogens for the light level upgrade instead.

With the LED's it depend on the ballast design. The series resistance types (ACRiche,...) are perfectly OK, they would just dimly glow.
Same behavior with LED's rated as dimmable: They would either glow dimly, or stay OFF, the ballast is (well, with good quality product) especially designed for such leakages, as these are common with practically all triac dimmers (the EMC filter)...

Thanks for the info   ah maybe replacing the old switch with a new one will solve the insulation leakage problem. The switch is only connected to one light as its in my bedroom and it does not have a neon indicator

The leakage could be within the wiring...
How long is the cable to the switch?
Or better: What isthe exact wiring topology:

CB panel
|
|
+----switch
|
|
Light

(here it could be the cable, even it's capacitance, if the branch to the "switch" is long enough)

or

CB panel
|
|
switch
|
|
Light

(here the only suspect is the switch)