Lighting Circuit Problem

[Usenet Nutter]

I have two lighting circuits ,one covering the Hall,Back BR ,Kitchen and Bathroom .The other covers the Front BR,LR and LR Cupboard . Yesterday I found the Front Bedroom light wasn't working and checking the circuit breaker ( Wylex Plug in type) and found it was in the off position .Thinking the bulb had blown and caused this I turned the breaker on but it immediately went pop and went off .I did it again with same result .I then checked the wall switches,a couple of juction boxes in that circuit and then checked the lampholders and found nothing wrong. I did notice that in the lampholder in the LR cupboard the lamp could be moved from side to side and wasn't being held properly .It was one of them curlywurly low energy lamps so I took the opportunity to change it for a "normal" bulb .I then tried the circuit breaker and all was well. All the bulbs were checked and found to be working . I am going to change that lampholder when I get a new one but is it possible that has been the cause of the fault...is it possible the bulb was sitting with only one of the contacts "making contact" .Could that cause the CB to trip? I was removing some stuff out the cupboard so may have knocked it on my way out...

[Owain]

More likely a loose wire or broken insulation inside the lampholder IMHO. As a high-resistance L-N fault that doesn't trip the MCB might still cause overheating leading to a fire I would suggest checking and if necessary removing the lampholder and making the connections temporarily safe.

Owain

[Harry Bloomfield]

Usenet Nutter expressed precisely :

The quick easy way to fault find - is to turn everything off, see if it will then reset, followed by turning things back on again one at a time until it trips.

The lamp contacts not making contact would not cause the tripping, but a faulty lamp holder could, a faulty lamp, or a fault (short) on the flex.

[NT]

Until fixed its an immediate fire risk. The mcb tripped because excess short current flowed, now hopefully none is flowing. When somewhere between the 2 flows, the result is fire.

NT