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Lighting vs Power

Published : 9th February 2005

Hello,

I'm looking for some advice regarding how much lighting equipment (In terms of wattage) I can power from a standard UK 240 volt ringmain.

My electrical knowledge is pretty poor and would appreciate and feedback on this subject.

All the best,
Liam Sanderson.
Filmmaker, UK


class="style9">>I'm looking for some advice regarding how much lighting equipment (In >terms of wattage) I can power from a standard UK 240 volt ringmain.

Most UK ring-mains are protected by 32A circuit breakers which at 240V theoretically gives you 7500 watts (7.5 kW). This does assume that there is nothing else on the ring-main, and you have to be careful that other devices have not been spurred off the circuit. The load should be distributed over several socket outlets and the lights should be switched on individually or in modest groups to avoid the inrush tripping an overly sensitive breaker.

Also beware of older buildings that may have dodgy wiring that can fail when subjected to a high current, particularly where poor joints have been made.

If you have complete control over the premises and know a friendly electrician, it would be possible to put in a completely separate power take-off point at the main distribution board. Allowing for normal running loads in the house, this could give you 60A or more to play with and could have it's own earth leakage protection for safety.

The latter arrangement would be best in a home based studio environment.

Clive Mitchell
http://www.bigclive.com


Liam,

A standard UK socket is 13 amp = 3,000 watts (in round figures). So that 's the maximum safe load for any ONE socket.

I believe your ring main system is fused at 20 amp = 5,000 watts total for all sockets on the one ring.

A handy formula: volts x amps = watts. In the UK I believe your nominal voltage is 230? Rounding it up to 250 makes the mental arithmetic easier and one can burn these figures into one's brain :

500w = 2amp
1kW = 4 amp
2kW = 8 amp
5kW = 20 amp.

Good luck,

Clive Woodward
Perth, Western Australia.



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