Cable for external 500W flood light

[joeb99]

Hi,

Im moving a light fitting outside, 500W flood light, standard unit. Its being moved higher up so i need to re-run the cable to the light as the old cable will be too short.

Currently, the cable to the light is flat grey T&E as used internally under the floor for the lighting ring.

What cable should i use? Light is 500W approx. 3A, so was thinking of 6A round flex:

http://www.tlc-direct.co.uk/Products/CA0dot75F3Bslash50.html

The cable length will be about 13m if that makes any difference?

 

[ericmark]

The minimum cables size for permanent fixture is 1mm. See Table 52.3 - Minimum cross-sectional area of conductors.
Otherwise likely it would be OK. Assuming protection is given where required. However permission is required I think for anything over 150W from local council under Part L and this means of course not such a simple operation so I would re-consider it really a good idea!
The volt drop 13 meters is quite a run at 44mv/A/m = 44*2*13 = 1.2 volts which is well within the 3% allowed but if there are other factors this could change.
I would consider Metal Halide as more light and under 150W so by time you remove costs of council charges likely cheaper than using 500W tungsten.
Also be aware of Part P.

 

[Aragorn84]

You can use any wattage Metal Halide as they fit into the "Energy efficency" band that is in the regulations.

150w of MH will be quite a bit brighter than a 500w halogen anyway.

 

[joeb99]

Thanks for ther tips. Metal Halide appears to be a special fitting, so not really cost effective, would takes years to recoop the extra initial cost v's energy saved.

 

[Aragorn84]

Its about 40quid for a fitting and lamp on top from the likes of toolstation

or ebay:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=180428701533
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=190336973768


And it has the big advantage of not contravening the building regulations, unlike your 500w halogen.

Does depend how your using it though, if its only on and off for short periods of time then MH isnt ideal.

 

[Steve]

I would consider Metal Halide as more light and under 150W so by time you remove costs of council charges likely cheaper than using 500W tungsten.

Eric, I would advice caution recommending MH for domestics, without giving them the main fact that they are only effective when burnt for several hours at a time.

 

[Aragorn84]

Surely they're fine, even if only on for say half an hour?

They only take a few minutes to warm up, and cant be restruck for 5-10mins after powerdown, but for floodlighting where its going to be used for recreational or work purposes, rather than a security light on a PIR, whats wrong with them?

 

[Steve]

Surely they're fine, even if only on for say half an hour?

They only take a few minutes to warm up, and cant be restruck for 5-10mins after powerdown, but for floodlighting where its going to be used for recreational or work purposes, rather than a security light on a PIR, whats wrong with them?

Nothing, I was merely saying that we shouldnt just say "use a MH instead", WITHOUT ALSO SAYING "if you're going to be using it for hours at a time".

Eric simply said "consider MH as it is more efficient"

Makes me laugh/cringe when I drive past a chinese near my shop. They have two 500w halogens outside, burning for 8 hours at a time in winter. And you just know that a spark wouldnt have fitted them (unless he was domestic and very basic, and didnt know MH existed)