Shed, pergola, ally and drive Lighting/Power.
The installation will consist of a number of LED fixtures and a few rarely used double socket outlets.
The switching will be wireless to reduce the amount of cable, damage, making-good and labour of the overall installation cost.
A 20amp 61009 should be sufficient to cover the maximum demand of this circuit. A switched fused spur housing a 3amp BS1362 fuse will be installed onto this circuit to protect the 1.0mm² lighting circuit.
Using Appendix 4 of the BS7671 I have calculated that to have a 20amp 61009 protective device on the 35m length of cable and not affect the 70°C PVC/PVC cabling within the shed, I will require the SWA cable to be at least 2.5mm². I’m hoping to have a volt drop of around 0.37Volts up to 8.82Volts.
I have in total:
5x 18W LED 2ft fixtures,
1x 20W LED floodlight,
1x 10W LED floodlight,
4x 5W LED IP65 recessed downlights.
As you can see a 1mm cable will be more than sufficient to supply the 0.61A of lighting. I have in the past been questioned as to why I choose to install some circuits in 1mm cable over the 1.5mm alternative.
There will be a total of 8x 13A outlets within the installation. I rarely see more than one being used at any given time. A lawnmower will likely be used occasionally. A typical lawnmower ranges from 900-1500 watts.
Even though the idea of premature collapse within a shed, especially of this size before the fire brigade arrives is very ‘chocolate teapot’ I have still gone ahead with affixing metallic cable supports. It’s a good way for me to drum this new installation method into my future routine.