outdoor electrics

[cdorling]

Hallo chaps
I'm wanting to install some electrics in the back garden, which will involve (hopefully) 1 plug socket outside the house, 3 plug sockets in a greenhouse (and possibly some low level lighting). I already have an armoured cable buried in the garden. To try and keep the cost down I wanted to buy and fit most of the plugs, switches, junction boxes etc myself, and then have a qualified electrician connect up & test everything. But before I buy all the bits at a local wholesaler I wanted to check that such a load can be met by simply taking the power from behind the double socket that is nearest my outside wall. I'd never use 4 x 13amp appliances all at the same time. Can someone tell me if there are limitations ampwise by doing it this way.
Many thanks.

 

[breezer]

you havent mentioned an rcd, ad how is the electricain going to connect an swa cable to an existing socket?

Best to have it on its own rcbo at the cu if you have no rcd protection

 

[Job_n_knock]

Not to mention a 4 twin socket radial connected to an existing ring !!!!!
Tell your Electrician that you want the job to be Labour only but you need to know what to buy and where to buy it. He will tell you how it MUST be done...no corner cutting is allowed. Then you can get the materials and he can do the rest. Show him the SWA that you have already, he will know what to do next.
For a start I suspect that 3 twin sockets in a green house suggests heaters to me or maybe some form of UV lighting. He can work out the load and protect accordingly plus, as Breezer says, you will have to feed this circuit from an RCD or an RCBO.
In theory this RCD can be from a spur connected to one of the sockets but I really dont think thats the best solution.

 

[cdorling]

Thanks for replies. I know I need it (and me!) to be rcd protected. I was thinking that the current socket for 2 plugs could be converted to an RCD one, with a 'spur' somehow taken from this to an outside junction box. I'd have the electrician most of this, and connect to the armoured cable etc. At any one time I might use one of a heater/hedge cutter/lawnmower plus a propagator/lights. I wanted 3 switched sockets so that I could keep the plugs waterproofed & out of the way, but turned off.

Thanks for the 'labour only' terminology tip. But 'rcbo at the cu' has got me. Is cu consumer unit? And would this involve a separate 'board' next to the main one with all the fuses on, that would then have a wire going out off somehow to join the armoured cable outside? Sounds like the £s would be added on, but at least I dug the trench for the armoured cable.

 

[Adam_151]

I was thinking that the current socket for 2 plugs could be converted to an RCD one, with a 'spur' somehow taken from this to an outside junction box.

How would that RCD protect the shed supply?! What you could do is dual acessory box, one side with a single socket, the other side with a RCD FCU (you need an FCU anyway if you are feeding it from the ring)

But 'rcbo at the cu' has got me. Is cu consumer unit?

Yes, consumer unit, and RCBO is an MCB with built in RCD protection

And would this involve a separate 'board' next to the main one with all the fuses on

It wouldn't if your board could take an RCBO, but if it has fuses then its very likely it wont be able to take one

I'd probably have the CU swapped for a new one and run the shed supply from that, or if not, just a separate mini-cu next to it

 

[cdorling]

Thanks Adam & JobnK.
I was only planning one single and one double socket (not 3 doubles). If the spur/RCD FCU is a silly idea, I'd be happy to consider the other option.

I may have mislead you re my cu - mine has 'trip switces', rather than the old fuses. I've just had a look and there seems to be one slot empty (but covered). The cu says it has a '100ma trip'. I've googled for an mcb, they seem to be less than a tenner. So is it as simple as getting one of these fitted and having a cable come from it & off to the outside, to be connected to armoured cable? I've also seen a £40ish 'Garage Unit 40A 30mA RCD+1x6A 1x16A SP MCB', would I need something like this, if so is it a fairly simple job to have it connected? Sorry if I'm going on a bit, but I'd really like to have an idea of the options & the potential cost before I get someone round. Thanks again.