I have been asked recently why light bulbs blow so often? and why does the circuit breaker trip?


All electrical pages are for information only! New rules have been introduced for electrical safety in the home, please read this document by clicking here, before starting any electrical work


Before working on any electrical circuit you must ensure that it is isolated correctly and cannot accidentally be switched back on. Please read the article on safe isolation procedures before doing any electrical work. If you are not 100% certain what you are doing call a qualified electrician. Building regulations are changing all the time and modifying your home electrics could be against new rules and could invalidate your home insurance, if in doubt check first!


If you have an older consumer unit that uses fuses it is also possible that when a lamp blows it also makes the fuse blow for the circuit, please see here for more information- Testing and replacing a consumer unit fuse In most cases the reason why lamps (light bulbs) blow is due to the cheap quality of the bulbs. I have recently attended friends houses who suspected a faulty light fitting as the bulbs kept blowing, After obtaining some good quality bulbs the problem subsided. As I have mentioned on other pages circuit breakers are far more sensitive than fuses and therefore the breaker will trip whereas a fuse would not, although It possible for the fuse to blow.


blown light bulbs

The circuit breaker does not trip because a broken filament has dropped onto a lead out wire as some people would have you believe but is due to the gas or filament in the lamp becoming ionised, the high temperature and large electric field can cause the gas to go into a conductive state and the plasma will spread until it shorts out the lead wires.

It always makes sense to check the Light fitting just in case a fault genuinely does exist, so with the electricity isolated at the consumer unit, check the lamp holders for signs of damage or blackening.