500W outside light - connect to lighting ring?

[andy1020]

Hi,

installing a new outside light. (500W halogen, PIR) Easiest install is to the lighting ring in the loft (easy access to wires and to outside)

However, my calculations are as follows - tell me if I'm right?

total lighting load at present:
spotlamps in bathroom and stairs: 4x50W (max) = 200W
other single lights (presume someone puts 100W bulbs in to be on safe side): 3x100W = 300W
Total: 500W

then add in 500W PIR light to get 1000W total for circuit (which is a ring for upstairs lights direct from the CU) which gives (at 230V) just over 4A, which is fine for a 5A circuit, yes?

I guess I need to check the wiring is actually at least 0.75mm but it will be if the fuse is 5A I guess.

Is there anything I've missed or is it safe?

Thanks
Andy.

 

[breezer]

It should be wired in 1 or 1.5mm twin and earth.

The surge may be too much for the mcb

Do your neigbours a favour, dont fit a 500w flood light

if you must have light use smaller wattage lamps, lower down. Having a 500w flood light high up sonds good, but it lights your neighbours gardens too, lights up any neighbour who has a garden at the back of yours.
and lighting cct is not a ring

 

[andy1020]

great, thanks.

It's actually for a side driveway just for getting the kids in & out the car in evenings and will be switched off other times, shouldn't affect neighbours too much, though I'll have a chat witht them obviously...
I'll be mounting it fairly low, so hopefully not guiding in the planes... do folks reckon 500W OTT for this? only need 150W?

and lighting is radial then.. OK! but it's safe to wire into the circuit as long as it's at leat 1mm?

and it's not MCBs in the CU, only fuse wire, so surge shopuldn't be a problem...

Thanks.

 

[davelx]

I have one of the small 150W floods lighting my front parking area - it's perfectly adequate for packing the car jam full of PA equipment & tools, so I'd think that would be enough for your purposes.

 

[breezer]

also a couple (or one) nice light with a cfl would be fine, and look nice too, and being cfl not matter if left on for a long time

 

[Pensdown]

... do folks reckon 500W OTT for this? only need 150W?

Halogen flood lights make better heaters than flood lights. The light output per watt of energy used is pretty poor. However, they are cheap to buy and the lighting is instantaneous.

In most circumstances a 150watt fitting is more than adequate and if not you're better of installing two or three of them a few metres apart than one 500watt fitting.

 

[breezer]

like you just said

150w lamp MORE than adequate.

have a 9w cfl

or for £2 this