Light switch, Max handling power to flood lights

  Ex plorer 14:30 19 Feb 2014
Locked
Answered

Hi I have started to have problems with my out side lighting it runs 2 PIRs rated 2000w each and 5 out side lights.

All has worked well for the past year but just lately when tripping the PR above the back door it throws the trip switch.

Total load from all lights WAS 1250 watts,

Bulb change Today to reduce wattage. 4 are floods total 870 watts, one is a standard outside light twin lamp 2x 40w.

Any one know what the maximum load that can be put through one switch I have Goggled for an answer but found little to give a proper explanation.

It was a DIY job taken from the original out side switch and junction box.

The lighting circuit is on 5amp on the old type pull fuses.

Installation of wiring was 39 years ago.

  wiz-king 16:23 19 Feb 2014
Answer

Most modern light switches are rated @ 6A which is 1400W approx. But the switch on surge of the bulbs will give a higher figure than the constant load. An old type fuse will have a small delay as the wire heats up and may pass greater current for a few milliseconds to cope with switch on surges.

I have 4 x 70W sodium floods and they used to demolish the switch in a timer rated @ 13A because of the switch on surge and I had to fit a contactor to cope.

  spuds 17:31 19 Feb 2014

"Installation of wiring was 39 years ago" might be an indicator of something wrong, if the system begins to suddenly trip after a number of years!.

I have just had a few problems with our outside security lighting, and in two recent occasions had a new halogen lamp explode and another halogen lamp apparently acting as a fuse, with filament burn out.

  morddwyd 18:58 19 Feb 2014

Might seem obvious but do check for water ingress.

Even a hint of dampness can cause problems.

  The Old Mod 06:37 20 Feb 2014

You don't say what this trip is, is it a MCB or an RCD. If it's a MCB then that would indicate an overload or short, if it's an RCD then most likely water or dampness has got into something. A normal light switch will be rated at 5amps but with the load you mention it wouldn't take long for the contacts to wear and start arcing. You can get a higher rated switch. My best bet though is that you are talking about an RCD so therefore I would suggest looking for water ingress somewhere.

  Ex plorer 09:51 20 Feb 2014

Thanks all, I have looked for water ingress, then sealed round grommets with an exterior sealer. I will double check.

A rewire is a good idea and I have looked into it and had some prices.

I have been out this morning and the oil boiler started up in this cold weather condensation is coming from flue and with a breeze its sending it up-wards to the first light.

That may be a problem also, and a good reason to move that light.

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