Electrical question

[Mr J Morton]

hello
All the lights have gone off. My Mrs seems to have a talent..blowing up electrical things. She regularly blows bulbs, in 5 years I've blow 2, she touches a light switch and blows a bulb and trips the RCD, up to twice a week. Her Dads the same he cant wear watches as they stop in a matter of days.

Anyway this morning at 6:30 she turns on a light and pop the RCD trips, the problem is this time when I switch the trip back no lights work. Its a one bed flat so there's only one light ring. I'm going to check the switches and light fittings.

I know there are some electrical geniuses on this forum so is there anything else I should check?

thanks

Jonnym

 

[GrahamGKD]

Hi Jonny,
Do you mean the RCD or is it the MCB that trips when a bulb blows? RCDs (normally none, one or two per consumer unit) detect an imbalance in the current between live and neutral - i.e. an earth fault of some kind. MCBs (one per circuit on the consumer unit) often trip because a filament bulb often fails momentarily short circuit and causes a brief over-current condition.

If it's an MCB, does it latch back on again - if not, have you removed the bulb which caused the trip in the first place. Personally, I can't think why a bulb failing would cause an RCD to trip?

 

[Mr J Morton]

Ahh MCB as its just the lights which go off all other power remains.

Yes MCB does latch back on.

thanks
Jonnym

 

[GrahamGKD]

Curious, can't think what would cause that. I had a quick look on Google - apparently MCBs can sometimes fail. Have you tried switching the MCB off and back on again? If you have the means and expertise to measure some voltages around the circuit (like on the switched side of the MCB for starters) that might shed some light on it (no pun intended). Otherwise, wait for one of our resident sparkeys to come along - they may be able to suggest something.

 

[Mr J Morton]

I've flicked the MCB a few times and they have come back on. I'm guessing a faulty MCB is to blame.

Thanks for your time
Jonnym

 

[brightspark]

99 percent of the time when a bulb blows it will knock the mcb out thats normaly the case . if it happens quite regular it could damage the contacts in the circuit breaker and would require changing .there quite easy to check with a meter or a test lamp providing your reasonably competent , [no dis respect ]

 

[Mr J Morton]

None taken, my competency knows no start. When testing it should I remove it? As it would appear to be an intermittent problem a visual inspection is probably not a bad place to start.

I suspect there is to much on the one ring and voltage drop causes the bulbs to blow. I'm going to replace one of the lights (6x halogen spots) with a 12volt one to see if it make a difference.

thanks
Jonnym

 

[pidgeon chit welder]

None taken, my competency knows no start. When testing it should I remove it? As it would appear to be an intermittent problem a visual inspection is probably not a bad place to start.

I suspect there is to much on the one ring and voltage drop causes the bulbs to blow. I'm going to replace one of the lights (6x halogen spots) with a 12volt one to see if it make a difference.

thanks
Jonnym

Those 12 volt bulbs can be far more prone to failure than you would want them to be especially if they are switched on or off a couple of times a day.

In our lounge we have three wall lights of 3 x 12 volt by 10 watt units.
Each light unit has its own 240 to 12 electronic controlled transformer .
To stop eddy currents and spikes & balance the wiring resistance etc each of the three wiring legs from the switched point is exactly 6 mtrs long and any spare is fixed to a board giving 200 mm separations so little or no induction effect..

In the last two years we have gone through over 40 of the 10 watt bulbs ..
all are supposed to be long life bulbs and have been obtained from a variety of souces and manufactirers.
They only seem to last a month or so in some cases .
Can you put in LED replacement bulbs that use 240 v initally and use their own internal circuit to step it down to led voltages.

Look on the eBay for ideas as there are lots of new bulbs in LED form inc 25 watt equivalent screw in replacements that are 3 watt LED jobbies .

I have all my GU10 50 watts x 28 bulbs as either 7 watt compact fluroscents or 3 watt LED's

 

[Mr J Morton]

I'm glad I'm not alone, changing halogen light bulbs has become more of a hobby I have to do it so often. I have been looking at the LED lights, perhaps I will try them first. The only success we had was with three mini 12v halogens in the bathroom which have been going strong for 5 years.

Jonnym

 

[pidgeon chit welder]

I know what you mean .. sometimes the transformers for the low volt low watt lights leave a lot to be desired and this is where you get the prob of bulbs blowing well ahead of time .

In my last house I put in seven quality new 12 v transformers & install new light circuits & fitings to run all the lights at the end of the day for I was being bankrupted having to get new 240 halogen bulbs .
The 240 v halogen bulbs run at very high temps , whilst they are on the slightest vibration/shock can wreck them in no time. Mains spilkes don't do them any favours either.