Outside wiring: a long distance from house

I am nearing completion of a deck in the far corner of our garden. I would like to add some lights and a water feature to it. The cable run from the house is approximately 30 metres. My questions are:
1) I am planning on connecting the wiring to a fused spur with rcd in the house. Will the length of the wire run cause a problem with the rcd (do not want it tripping every 30 seconds)
2) Will I be able to use the one run of cable for both the lights and the water pump or will I need to run two seperate cables.
Thanks
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Should be fine on both counts.

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Most installations of this type use SWA (steel wire armoured) Cable for safety reasons. SWA gives more protection against intrusion to live conductors from sharp tools or fencing stakes etc. and should be buried to no less than 800 mm if not protected by any other materials. It should also have a warning tape buried along with it, preferably 200 - 250 mm above it, to tell people that a live cable is below.
Depending on the full load you're thinking of fitting at the end of the cable, then you should be OK with one run of correctly gauged cable. But I would ask you to check the full load of all lights and the water feature when all are being switched on at the same time, as this will affect the total current drawn through the cable. Also, an RCD is very much needed on this type of installation, and it should be coupled along with a good earth bonding, preferably at both ends, to provided a bit extra safety coverage if working with digging tools and the likes.
The full load calculation will give you the gauge of cable you will need to safely supply all the appliances and also tell you the trip value of any automatic breakers you'll need to use. I would also ask you to take into consideration, the fitting of an all weather outdoor socket at the decking area. This will allow you to work with power tools or cleaning appliances without the need to run extra extension leads and things.
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On Wed, 27 Aug 2003 12:55:37 GMT, BigWallop wrote:

I'm thinking of doing something similar - greenhouse heater for frost protection this winter (only when needed). What would be the maximum power I can *safely* take from the spur?
TIA.
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13A. This gives 3120W actual, or 2990W nominal. This depends on the circuit you are spurring from having the balls. I wouldn't spur off a kitchen ring main, which has lots of power hungry appliances attached. Best is a new circuit with RCBO protection.
Christian.
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On Wed, 27 Aug 2003 16:41:18 +0100, Christian McArdle wrote:

Thanks Christian. Looks like I'll be *well* below that - 2Kw heater not on the highest setting so using around 1Kw. I was a bit concerned because there is another (not high power) thingy connected to the same (double) socket.
Thanks again.
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If it does, there is a fault in the cabling (or final load).

Yes you can. However, if you want to be able to switch them from the house, you'll need separate supplies for both.
To calculate the cable size, add up the total load. Then go to www.tlc-direct.co.uk and find the cable you want and bring up the information page. Somewhere you will find a link to the cable size calculator. Put in the required details (i.e. 2 core SWA XLPE and 1000W) and it will tell you what minimum cable size you need. The selection will probably be voltage drop limited. You might consider trying 3120W, as this will enable the full benefit of your RCD fused spur should you choose to install an IP66 socket. You may wish to check the final calculation directly against the regs.
BTW, I tried 3120W @ 240V with SWA XLPE 2 core, with 30m and it suggested 2.5mm. It uses a large proportion of the allowed voltage drop, so any long runs inside the house may tip it over, requiring 4mm.
Christian.
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"Christian McArdle" wrote | >2) Will I be able to use the one run of cable for both the lights | >and the water pump or will I need to run two seperate cables. | Yes you can. However, if you want to be able to switch them from the | house, you'll need separate supplies for both.
Unless something like X10 remote switching is used (in appropriate IP rated enclosures)
Owain
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