MCB - Short Circut

We had a short ciruit recently which quite violently tripped the MCB (over the course of fault recognition this happend 5-6 times), we repaired the offending Light that was causing the short and all seemed fine.

Then recently our MCB started making loud buzzing noises when all the lights were on, our electrician told us the MCB was over loaded and started to colapse under the strain (hence the buzzing), he replaced the MCB and all seems fine, except he told us to reduce the wattage in all our lights. Now at pressent we have about 730watts worth of lighting on that MCB which doesnt seem too much...... does anyone have any advise here should I replace the bulbs or was it the short that damaged the MCB, what sort of guidelines should I work to. I have a 500watt security light which is currently off..... I want to turn it on but I dont want to do any damage.

Thanks for any response

The maximum load for a single 5 amp lighting circuit is 1200 watts, and shouldn't exceed 10 lighting points. That security light is much more powerful than your average lighting point - you should consider giving this its own circuit. Don't just upgrade the mcb - that would leave your standard light system insufficienly protected.

yhe other thing you could do (easy) is to change your lamps to "energy efficiant ones" or fit low voltage halogen lighting. saves money in the long run.

The only snag is energy efficiant lamps can not be dimmed, and lv lighting needs a special tranformer if it is to be dimmed, that said some do now come with dimable transformer

Thanks for the response, I consider moving the security light, although I dont know how.... probably best just to turn it off for now