Garden Electrics

bwhitton · Posted: Sun Nov 06, 2005 2:45 pm Post Subject: Garden Electrics

I have a 20m garden with a shed at the far end. I have a small consumer unit my the house with sufficient spare ways. I wish to have 10 bulkhead lights along the length of the garden 2-way switched. I also wish to have 2 waterproof socket outlets. What is the most economical (in terms of cable runs) way to do this? Should I use SWA or run singles in galv conduit?

Lectrician · Posted: Sun Nov 06, 2005 3:06 pm Post Subject:

Every install is different. Are you prepared to dig a trench, or happy with surface wiring?

20mm plastic conduit, with tee boxes below each light may be the best option. 20mm glav would be more robust, but the conduit does age in the weather, and can look a little to industrial.

If you use armour, trenched at the foot of the wall (I assume wall), put a galv trouser box, or a plastic gewiss type box below each light at low level, and run a stab of conduit upto each light. (again plastic or galv).

If using SWA, you would need a 4 core. 1 core for Neutral, 1 core for constant live, 1 core for switched live, and the final core to common the two common terminals of the switch. The armour would be the earth. You would need a seperate run for the sockets.

An idea of what you are fixing to, or even a photo would help.....

Where in Devon??

bwhitton · Posted: Sun Nov 06, 2005 3:15 pm Post Subject: Garden Electrics

Thanks for that quick reply,

To add, bulkhead fittings are to be mounted on a stone wall, no probs with surface cabling. If i was to run in conduit, should I run the lighting circuit as a ring or can I just use a simple spur arrangement? For the socket outlets I should be okay for space in the conduit?? Or not. I would prefer just to have 1 piece of ironmongery on the wall for neatness....

Lectrician · Posted: Sun Nov 06, 2005 3:29 pm Post Subject:

One run of conduit should be fine with no bends (using circular angles and tees as required).

The cable factor for 7 2.5 singles is 7x30=210.

The cable factor for a 10m run of 20mm conduit with no bends is 244 - ok, but will be tight.

The cable factor for a 10m run of 25mm conduit with no bends is 442 - ample.

I say 7 2.5 singles, as it would seem a waste to buy 100m drums of both 1.5 and 2.5 cables - wire the lot in 2.5mm.

I would be tempted to run 25mm across the wall, with 20mm upto the lights.

Share the earth between the two circuits, 2 cores for sockets, 4 cores for lights.

Dont forget an RCD for the sockets.

Dont forget about part P!!

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The reason I calculated the runs as 10m, is this is the longest listed on the chart.

If you start pulling the cables in from the centre, which most people will do, it's 10m each way