Blowing Switch

[mrwoof]

I have just replaced two light fittings with two fittings each with 4 50watt halogen bulbs. These are connected to the same double light switch (not dimmer)as the previous fitting. Switch is a double switch from B&Q and reads 6Ax250VOLT on the back of each switch. Sometimes the lights work but twice, one of the switches has blown. I have checked the light fittings and wiring with a meter, no short circuits and everything reads as it should. Wiring is normal lighting wire but this is connected to a ring main rather than the house lighting circuit. No problem with the previous fittings. Any suggestions where I go from here?

 

[ProDave]

1) you have 400W of halogen lights from one switch. That's an "on" current of under 2A, so the switches should be okay. but Halogen's have a high inrush current at start up. Most light switches these days are rated at 10A

2) Lights should NOT be wired directly from a ring main, the cabling used is not rated for the available current. Okay if it's fed from a ring main via a FCU (Fused connection unit) with a 3A fuse in it.

 

[Theorysparky]

is it fused down at the point of leaving the ring ??

what meter did you use ??

are you sure the switch is wired correctly ???

 

[Doc Hudson]

I have just replaced two light fittings with two fittings each with 4 50watt halogen bulbs. These are connected to the same double light switch (not dimmer)as the previous fitting. Switch is a double switch from B&Q and reads 6Ax250VOLT on the back of each switch. Sometimes the lights work but twice, one of the switches has blown. I have checked the light fittings and wiring with a meter, no short circuits and everything reads as it should. Wiring is normal lighting wire but this is connected to a ring main rather than the house lighting circuit. No problem with the previous fittings. Any suggestions where I go from here?

Welcome to the forum, How many switches have you replaced when you say they have blown? there is no such thing as 'normal lighting wire'. If the switch 'blows' does you fuse at the fuse box 'trip' or 'blow' as well? do you have RCD protection? what type of fuse box? wire or switch?

Doc H.

 

[matt.leung]

do u mean the switch contact has failed... it seems loose and there is no click once switched....

 

[mrwoof]

Thanks for the replies everyone, especially ProDave. Looks like that is the problem, I'll replace the halogens with LEDs.

 

[Doc Hudson]

Thanks for the replies everyone, especially ProDave. Looks like that is the problem, I'll replace the halogens with LEDs.

Without some further testing I would not be so confident that you have found the problem. There are hundreds of properties with large 500watt halogen garden floodlights connected back to a switch with no adverse effects. On your initial post, "I have just replaced two light fittings with two fittings each with 4 50watt halogen bulbs. These are connected to the same double light switch" did you mean that each half of the double switch is turning on one fitting, so each switch only operates 200w (4x50w). Or are both fittings working off the same switch with the other part of the double switch controlling something else? You did not answer about how many switches have you replaced when you say they have blown? Or when the switch 'blows' does you fuse at the fuse box 'trip' or 'blow' as well? do you have RCD protection? what type of fuse box? wire or switch? If there is a cable fault, such as trapped shorting to earth after insulation heats up, it will still blow no mater how often you change the lamps.

Doc H.