Floodlights keep tripping out?

17 Jan 2006
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United Kingdom
Ive got a problem with my outside lights keep tripping the main fuse for them. Originally there were two 100w bulbs connected to a sensor and wired into a 6 amp fuse in the garage fuse box. As they didnt light up much of the driveway i removed the 100w bulbs and fitted a 150w and a 500w floodlight in their places. This seemed ok for a while but i moved the 150w to a basic cable and plug so i could move it round the garden and then put another 500w floodlight instead so i have two 500w floodlights on one circuit. The thing is, after them coming on a few times, for about 30secs, the fuse trips out. Is 1000w too much to go through a normal lighting circuit or is a different rated fuse needed for these type of lights? The cable is quite thick so i dont think its that what is causing the problem, its around 12-15mm 3 core flat grey cable. Any ideas on what to do to get both lights working off the same sensor?
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1150w is less than 6 amps, so those items alone should not cause problems. If there are other items on the same circuit, it is probably overloaded.
The other possibility is a damaged cable, faulty connection, or perhaps the sensor is not rated for two 500w lights.

However, fitting 500W lights will contravene building regulations due to the huge amount of energy they will waste.
Is there anything else running on the 6A mcb?

2x500w bulbs is a load of around 4.2A at 240v so that in itself shouldnt be enough to trip the MCB...
There are three fuses in the garage,one for internal lights, one for sockets and one for the outside lights. The sensor is is seperate to the two floodlights so i can aim it higher where i need to while still having the lights aimed downwards. Im not sure what the sensor would be rated for though because that was here when we moved in. I might have to have just the one light on the sensor and move the other to the other side of the garden on a switched cable. On another wall i have a 150w light connected to the house lighting circuit. Would it be ok to run the other 500w light from the same light switch or would this keep tripping out the fuse too?
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Interesting to note the pic in Flameports post. That means I cannot fit a 500watt flood in my garden, by what regulation can building control stop me lighting my garden for sufficient safety, or is this another case of this nanny state and the current obsession with power saving. I am paying the bill.
150 is plenty to light a garden.. if you have a particularly long garden, the put another 150 further down..
a 500W is just light pollution..

and we all pay the bill.. it's all extra carbon that gets put into the atmosphere..
Might as well really push the boat out....

1000w high pressure sodium meets those regs and would light half the street :D

Go on, you know you want to :p
if you dont understand that was a joke nor get the meaning of the lol smilie i dont think you should be anywhere near a computer never mind your electrics...

The whole HPS lamp thing was a bit of tounge in cheek overkill due to Mr coljack trying to enforce his views on how much light one requires to light their garden, and the responding posts by spark and myself were continuing that theme.

On a serious note, if you do want more than 150W of light then something like a HPS lamp would be the way to go, as they meet the 40lumen/watt limitation specified in those regulations, although a 1kw HPS might just a bit over the top, as a 150w HPS would probably produce similar amounts of light as a 500w halogen, so it even has some green credentials.
if you dont understand that was a joke nor get the meaning of the lol smilie i dont think you should be anywhere near a computer never mind your electrics...

I don't know if you realised, but this is a DIY forum for people who do not know much about electrics to ask quesions.

I assumed your post was supposed to be a joke, but your average DIYer might well not do.
and selotape won't hold a modern MCB up as the mechanism will still trip :p

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