I'm just about to start on a kitchen refit and have two sets of 6
downlights to wire up. Due to the layout of the Kitchen and wanting to
be able to easily access/replace transformers I have the 12 Downlights
across 6 transformers in configurations of
Cabinet Lights 3 + xfr, 1+xfr, 2+xfr
Worktop Lights 3 + xfr, 1+xfr, 2+xfr
Each lamp is 20W, so I'm using 60W transformers.
My requirement is that the Cabinet lights and downlights are on 2
separatly switched circuits so Cabinets and Downs can be switched
independantly (all Cabinets on/off, all Downs on/off)
I would generally wire this into the Lighting circuit, but I don't
have a separate Lighting Circuit for the Kitchen (and no room to
expand in the CU).
I have the following lights on the same circuit downstairs :
Main Room * 2 lamps = 200W (using 100W min
Front Room Candleabra (5 *
30W) = 150W
Front Room Wall Lamps (2 * 30W + 1 *
30W) = 200W (using 100W min rule)
HallWay (1 + 60W) = 100W (using 100W min rule)
Understairs (1 * 60W) = 100W (using 100W min rule)
Outside Light (1 *
60W) = 100W (using 100W min rule)
Downstairs ex.Kitchen Total therefore 850W
In The Kitchen I'll have 6 * 60W XFRs and say 400W worth of main
lighting = 760W
If I were to use the 100W minimum rule on each XFR, that'd be 1000W
So depending on how this is calculated I could end up with a max total
load of 1850W = 8A
The CU is a Wylex standard pluggable type and the pluggable MCBs are
5A for the Lighting Circuits.
1) do the Transformers have to be taken as a minimum 100W per unit as
per normal light fittings when calculating the load ? If I can
calculate them at their rating, I end up with a total of 360W Xfrs +
400Main + 850W = 1610W = 7A. Or can I even take their actual load = 12
* 20W = 240W + 400W Main lighting + 850W Downstairs = 1490W = 6.5
(still over the 5A Circuit tho)
2) Is there diversity applied to lighting ? and is it sensible given
that all downlights, cabinets and main lights are probably going to be
on much of the time along with about half the lights downstairs at any
one time ?
3) The LV XFRs come with Plugs so appear to be aimed at a Ring Main
circuit anyway (for which i have spare capacity). However you can only
have one socket per spur AFAIA and I would have 3 transformers
distributed along the wall to wire onto the same switch..
any help much appreciated..