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[PAULH6]

Hi gents, moved into a house about a year ago and renewed the switches and socket fronts. We also had somebody competant renew the all the fuses as they were the old type to flick switches (and checked by an electrician). Since then the bulbs seem to last a couple of weeks and then go, tripping the switch in the process. This isn't confined to upstairs or down and is random, there are 2x different fuses for up and down so am assuming 2x different circuits.
Many thanks. Paul

[ericmark]

It is very unlikely your improvements are causing the bulbs to blow. More likely you are getting slightly over voltage. Rough service bulbs will last longer also the use of energy saving bulbs will most likely help.
As to tripping the Switch (MCB) good quality bulbs have fuses built into the bulbs as when they blow ionization causes a short circuit for a few seconds. Cheaper ones don't have these built in fuses and MCB's are quicker acting than fuses so it takes out MCB where fuse would survive.
The supply company is allowed -6% to +10% from the 230 volt standard OK with most things but not bulbs which at +10% don't last very long.