Bulbs keep blowing in lounge

[wazzag]

Once a week one of the bulbs in my lounge blows whe I turn them on which always causes the RCD in my main CU to trip. The bulbs are always within wattage rating (40), the lights are wall mounted up lighters. The circuit has not been modified although the lights were changed about 5 years ago. The problem has been happening for about 2 months now. I've changed the light switch twice but that makes no difference otherwise nothing much has happened that I think coud have caused it.

Any ideas what could be wrong?

 

[RF Lighting]

Stop buying cheap bulbs.

 

[sparkwright]

Obvious things to check are;
Cheap 'bulbs'?
Bad wiring connection somewhere?
Worn lampholder contacts not making good contact?

 

[ban-all-sheds]

If it's not a dimmer switch use CFLs instead of incandescents.

 

[wazzag]

I've replaced 3 of the 5 bulbs with CFL so we'll see what happens.
Thanks all!