On Sun, 02 Aug 2009 15:41:00 +0100, John Rumm wrote:

PeterC wrote:
On Sun, 02 Aug 2009 04:23:58 +0100, John Rumm wrote:

* How do I ensure that I'm not overloading the circuit?
Check the circuit breaker rating. Chances are its 6A. That limits the
total power to just under 1400W. To assess the size of of the existing
circuit then count 100W (or the actual rating if larger) for each light
position and just add em up. Sounds like you probably have over 1200W spare!

Is it necessary to allow for PF with CFLs?

No, because according to the sizing guidelines the smallest power you
count is 100W - which is way more than a CFL even allowing for PF.

In the loft I have 7x11W CFLs, so 77W, but the PF is poor and so they're
about 145VA. The 30W CFL in another fitting is about 31VA - pity that the
lower wattage ones aren't as good.

You still treat the 7x fittings as 700W of load; since you could
realistically expect someone to install GLS bulbs and need to allow for it.

OK, thanks. It'd stand that but 100W lamps might melt something; I'd better
put in dome ally reflectors/heat shields. I woudn't put even a 40W GLS near
anything that might suffer from the heat, but I've seen several things
melted by over-powered lamps.
--
Peter.
The head of a pin will hold more angels if
it's been flattened with an angel-grinder.