Running power from house to pond

BigBadDave · 1 Oct 2009

Hi all, first post here...

I will be building a pond in my garden soon and I need an electricity supply to power the pump, uv filter, lighting etc. I will be using SWA cable buried under my patio (500mm deep with hazard tape). I plan to connect to the mains using RCD then plug.
There's a few things I would like you guys to give some advice on;

The cable length will be 20m, what thickness should it be, and do I need to run it in conduit?

Also, what are my limitations for this project when it comes to part P regs?

Cheers, Dave

ban-all-sheds · 1 Oct 2009

BigBadDave said:
I plan to connect to the mains using RCD

So the circuit you plan to use is not already RCD protected?

then plug.

You can't terminate SWA in a plug. And why a plug, anyway? Why not a switched FCU?

Also, where and how do you plan to connect to the pond equipment, and switch it on & off?

The cable length will be 20m, what thickness should it be, and do I need to run it in conduit?

You don't need conduit, as SWA doesn't need extra protection. As for the size, only you know the load....

There's a reasonable calculator here: http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html

Select 2-core PVC SWA, even if you'll be using 3-core or XLPE, or it'll make the wrong assumptions.

Also see this for useful info:

http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf

Also, what are my limitations for this project when it comes to part P regs?

I don't see how we can say - P1 requires that "reasonable provision shall be made in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury", but we can't tell if your limitations will prevent you from doing that.

Also this work is notifiable - see //www.diynot.com/wiki/electrics:part-p.

ericmark · 1 Oct 2009

There are some plugs which will take SWA cable but these do not include the standard 13A type so to terminate it will require a box. Likely the same box as you intend to use for the RCD. However assuming at a later date you may want to put whole house on RCD protection then using a 10ma type for pond would make sense and one has to be careful on type used as the price will vary a lot. I used a metal clad 10ma RCD socket as it was in my spares box and a metal clad socket box with stuffing gland to change from flex to SWA not best but what I had to hand at the time.

Of course this limits power to 13A which is likely enough and at 13A even 1mm² will be enough to take current only volt drop and ELI will require thicker cable.

At 20 meters and 13A the volt drop would be around 11.44 volt which is just within limits for power. But if the origin already has some volt drop you may well need a heavier cable. The same with ELI without knowing the Zs at socket it can’t be calculated so I would use at least 2.5mm².

You will not need conduit the SWA is enough.

As to Part P this will only apply if the garden is attached to a dwelling building and in most cases this will be the case but an allotment may not fall into the requirement. In general to comply using the LABC route will cost over £100 to register the work as there is a min charge Ok if part of bigger project but other wise cheapest option is to get a registered electrician to do the work. They may do it at reduced cost if you dig trench. But either way all needs doing Before work starts.

stargazer · 1 Oct 2009

ban-all-sheds said:
Also see this for useful info:
http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf[/QUOTE]
Does anybody know what has happened to Kevin Boone and his website?
He’s gone off air now and all you get now is an agreeable picture of this blond

And a message

The domain kevinboone.com has expired.

Click to expand...

Steve · 1 Oct 2009

u got her number?

BigBadDave · 1 Oct 2009

Thanks to Ban-all-sheds and ericmark for the useful advice, and thanks to stargazer for the pic of the blonde, definitely brightened up this topic.

You can't terminate SWA in a plug. And why a plug, anyway? Why not a switched FCU?

I was going to terminate the SWA at the RCD using a gland, if it will take it. If not I would use a junction box.

Also, where and how do you plan to connect to the pond equipment, and switch it on & off?

I'm going to be using a switch box for ponds, where you can switch on/off the different components. This will be located within a bricked enclosure behind the waterfall, along with the filter.

There's a reasonable calculator here: http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html[/QUOTE]

Very handy thanks. I entered 2200W as that's the switchbox's capacity and it suggested 1.5mm, but taking ericmark's advice, and allowing for any future additions, i'm going with the 2.5mm.
As for Part P, looks like my best bet is to get a registered electrician for connection, testing and sign-off, but as ericmark said i'll get the digging out of the way beforehand.

Thanks again for the advice everyone!

flameport · 1 Oct 2009

BigBadDave said:
to get a registered electrician for connection, testing and sign-off, but as ericmark said i'll get the digging out of the way beforehand.

Get the electrician in first, no sense in spending hours digging and then finding they don't like that route for the cable.

ban-all-sheds · 1 Oct 2009

BigBadDave said:
I was going to terminate the SWA at the RCD using a gland, if it will take it. If not I would use a junction box.

This is an RCD:

BigBadDave · 2 Oct 2009

flameport said:
Get the electrician in first, no sense in spending hours digging and then finding they don't like that route for the cable.

Good point, i'll get someone over first. Thanks

BigBadDave · 2 Oct 2009

ban-all-sheds said:
This is an RCD:

I was hoping that there might be variations but I guess not. As i am now getting an electrician round before hand i'll see what he suggests. I'll also get a quote for connecting to the CU instead. Thanks.

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Running power from house to pond

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