External power extension - query suitable cable Ask questions and find answers to many subjects relating to electrics and electrical work

[stephenk2005]

Dear All - With winter upon us we have some very cold chickens and we wish to extend power to our stables. The power would serve 2 x low energy lights (total wattage 24 watts) plus 2 heat lamps (total wattage 500w) - thus total combined wattage of 524 watts. The linear run of the required cable from internal RCD spur to switched socket (IP 56) would be circa 70 metres.

Please could you advise me what cable would be most suitable - my thoughts are SWA armoured cable but I do not know whether 1.5mm or 2.5mm would be most suitable.

MANY THANKS

[BLAKEY1963]

[quote="stephenk2005"]Dear All - With winter upon us we have some very cold chickens and we wish to extend power to our stables. The power would serve 2 x low energy lights (total wattage 24 watts) plus 2 heat lamps (total wattage 500w) - thus total combined wattage of 524 watts. The linear run of the required cable from internal RCD spur to switched socket (IP 56) would be circa 70 metres.

Please could you advise me what cable would be most suitable - my thoughts are SWA armoured cable but I do not know whether 1.5mm or 2.5mm would be most suitable.

MANY THANKS[/quote]

stephenk2005
your electrician would start at 2.5mm2 but i am sure
he will evalueate cable calculations and give u the size
to allow for any change in load increase changes.

BLAKEY1963

[juli-juan]

get an electrician to come and look as any modifications to your wiring must be covered by part p as u are changing the wiring to your building also as live stock are conserned there are special regs that apply as well so call a sparky because ALL elecrical mods require a certicate

[ericmark]

I add it up as 1048 watts thats approx 5 amps with a max of 9.2volt drop thats approx 2 ohms max divided by 70 meters thats 0.03 ohms per meter max or to put it another way 30 mV/A/m and 1.5mm is 31 mV/A/m so that is the smallest cable you could use. Allowing for errors 2.5mm seems to be the best option. As to Part P that would only apply is your not in Scotland and someone lives somewhere in the system. So if supplied from your house then yes Part P but if part of farm building where no one lives then not Part P. If part P then non emergency work needs notifying before it starts. One may consider stopping chickens freezing is emergency work? In which case you can post work inform the local authority. As to live stock some times 110 volt split phase supplies are required I was having kittens when my 2391 exam question was in a stable but I passed and I gave answers using 230 volt so not all farm items need to be 110 volt. If the items do need to be 110 volt that doubles the current so then 4mm cable would be required if transformer is at the source. You need to read Section 605 of BS7671:2001 there are so many if's and but's I would not attempt to say how your systems stands under these regulations.
So if in hurry to save chickens use 4mm then what ever is the final outcome it is big enough.