In common with a lot of others, many years ago we upgraded the lighting in various rooms and installed heaps of GU10 30 watt / 50 watt incandescent lights, only to discover that they are completely unreliable, they only last a 10th of their stated life and when they blow, they normally fuse the circuit they are connected to.
You might read all sorts of reasons as to why they blow. Ignore them all. They blow because they are badly designed. The awful design also extends to the connector method. Fun to fit as well - aren't they? If the very ends of the connectors had been mushroom-shaped rather than square, they would be a doddle to fit. I digress.
They are terrible. You'll need to replace all the fittings for a different type of lamp, or opt for an LED replacement bulb. With the EU directive on incandescent lamps, your options are limited. We changed one room for GX53 (fluorescent/led mixed). The light from these is pretty good, but they are still not very reliable and quite expensive. (The fluorescent tube part fails and the plastic diffuser becomes browned and burnt).
New type of LED replacement lamp
In desperation, I recently tried a handful of replacement GU10LED lamp designs. The Luna Par 16 GU10 lamp (Amazon) proved such a brilliant sic replacement that I was prompted to pen this article. I have no affiliation wit Amazon or Luna (whoever they are?)
The light these give is as bright (brighter even?) as the original and the lamp colour temperature is exactly the same a standard incandescent GU10 lamp.
I have no idea if they will last the claimed 30,000 hours (that's about 3.5 years of constant use), but I will keep this page updated with their progress.
They are quite expensive (£9.99) but if they last half the time they claim, they will be cheaper than any incandescent GU10. At 6 watts, compared to 50 watts, the running cost will be an eighth of a standard GU10, if my math is credible.
Give them a try, I'm certain you will be delighted.