DIY Doctor UK DIY Forums

Hi we recently put up new light fittings in our sitting room. They worked fine for a day then out the blue kept tripping electric and blowing a bulb whenever it did. We have old black and red wiring and the new fittings require 3 g9 bulbs in each. It seems to have blown the whole fitting as we have tried new bulbs and they still worked then tripped. Any advice be great as we currently have only a lamp for light.

What "trips"?
Are you using Halogen or LED lamps?
You said "fittings" (Plural) does the same thing occur with all fittings?
Does this happen as you turn the light on or off or after some time of being on?
Does the light fitting say what type of lamp is required?

When you fitted the G9 lamps to the light fitting, did you touch them with your fingers. These are halogen lamps, they will possibly overheat from the moisture from your skin. Need to be held with a glove or tissue paper.

I have G9 fittings which caused a lot of problems, the normal G9 bulb [attachment=1]G9-small.jpg[/attachment] is two small to have the capacitors and by-pass resistors found in larger bulbs. And the larger G9 bulb [attachment=0]G9-big.jpg[/attachment] will not allow the covers to be fitted, with the old quartz bulbs the covers MUST be fitted as when the bulbs fail they can allow red hot bits to drop on the carpet, so real fire risk without the glass covers, but with the two bulbs shown since LED the covers are not required, and with larger bulb simply will not fit anyway.

The bulbs (LED) limit the current used with a capacitor built into the bulb, it is unlikely that the bulb can ever cause a MCB or RCD to trip, the quartz bulb however when it blows can ionise the gases inside the bulb causing a bright flash, this can for a few seconds use 100's of amps, and the bulb it simply too small to contain a built in fuse, so often when they fail the MCB will trip, that is normal.

The large bulb shown has a smoothing capacitor inside, and worked with electronic switches with no flicker, the smaller one has no smoothing capacitor and unless used with at least on quartz bulb would shimmer when switched on. It is clearly too small for the manufacturer to fit a capacitor, also the small version with an electronic switch with no neutral would flash when switched off, and a load capacitor is required to stop it.

The daft bit is the large bulb was cheaper and a larger output advert said "G9 69-SMD 5050" there is no lumen marked on bulb and no watts marked on bulb, in UK we are not permitted to sell the bulbs, some where between 4 watt and 12 watt, depends on the advert you find, they are brighter than the 2.5 watt of the smaller bulb.

I bought 5 well my wife bought 5, and one went faulty, so she got another 4 of the larger bulbs, I decided to take the bulb apart to see what was inside, I actually found the fault and it was returned to service, a simple dry joint, however the smoothing capacitor inside the bulb is nearly as big as the whole 2.5 watt bulb, so clear why not fitted in smaller bulb, they will simply not fit.

However the whole lamp without the glass covers may work better and give more light, but does not look as good, but wife will not complain as I told her before we bought it not to get G9, so she knows the answer she will get if she says how ugly the bulbs look.