new power socket by outside door?

[very_pointy_ears]

Hi,

Are there any regulations regarding the positioning of power sockets near outside doors (socket would be indoors)?

I would like to add a new socket in our back porch. It would be within a couple of inches of the door frame (hinge side) at a height of about 4 feet (just below the light switch). It's to power a microchip reader cat flap.

There's no power in that room (aside from lights) but one of the kitchen sockets backs on to a common wall so I could drill through the wall and cable in to the kitchen ring from behind.

The kitchen ring is RCD protected at the consumer unit (wiring is to edition 16).

Unfortunately the socket that I'd have to tap into is already feeding a spur so I'd have to make the new socket a ring socket, which would mean putting a little joining block behind the socket.

Aside from needing a qualified electrician to sign it off, are there any regulatory reasons why this shouldn't be done?

 

[PrenticeBoyofDerry]

It all sounds okay.
You have RCD protection I assume that is 30mA.
You can not spur from a spur and two spurs can not be taken form the same outlet, so extending the circuit so it complies is a good idea.
An alternative would be to install a 13A FCU in between the socket you intend to take the feed from and the already spurred socket and your additional one in the porch. If that makes sense?

 

[very_pointy_ears]

Hi, thanks for your reply. Yes that all makes sense.

The spur socket is about 10 feet away from the socket where I'd need to tap into the ring so it's not feasible to attach to the spur.

I've had a wee browse around this topic and have noticed people mentioning soldering cables together as an alternative to crimping or using a choc block. Is this considered an acceptable way to join cables? Naturally I'd put heat shrink over the join; presumably this has to be coloured brown and blue for live and neutral and I guess I can use regular green/yellow sleeving for the CPC.

There might not be room for a choc block behind the socket. I've not checked but if I remember correctly the back box is 35mm deep. At least it's a double socket so more room to work in than a single.

 

[very_pointy_ears]

Forgot to mention yeah it's an 80A/30mA RCD in the consumer unit. It's the one that came with the consumer unit when I bought it around 2008/2009.

I figured that the new socket needed to be properly fed and protected, not least because although we're only using it to power a small PSU for a cat flap, future residents may decide to plug in a lawnmower to it.

 

[PrenticeBoyofDerry]

If the back box is 35mm double and the socket outlet plate is not the flat flush kind, there will be plenty of room for a couple of connection blocks in there.
Soldering although an option is not as straight forward as it sounds.
I would extend the ring final circuit, if you can not do this without joints, connection blocks in the back boxes are acceptable.

 

[very_pointy_ears]

Hi.

Yeah extending the ring was what I'd assumed I'd have to do.

Sockets are standard MK sockets. Nothing fancy flush mounting or anything like that.

I'll pop the socket off to see how much space is in there. If memory serves (I replaced the socket a couple of years ago) I might be tight on wire length behind that socket so I may not be able to make the cables stretch to the edge where there might be more space. I'll have a look and weigh up the options when I find out what the score is.

Thanks once again for your help.

 

[PrenticeBoyofDerry]

If they are nothing fancy and just your stand socket outlet plate, should be plenty room.
If not can you get under the floor and is a bit of remedial work to the plaster out of the question?

 

[very_pointy_ears]

Hi,

Yeah that's completely out of the question - it's a solid concrete floor.

The cable comes down from above but the rooms have not long been re-plastered and decorated too so I want to avoid chasing in if I can.

 

[PrenticeBoyofDerry]

Well connection blocks in back boxes sounds favourite.
You do know how to extend the ring?

 

[NewOrder]

Is running a fused connection unit not an option here? I completely understand why you cannot spur a socket of a spur but why is the harm in running a 3 amp connection unit from that spur?

Only asking why that would be wrong, as I want to learn .

 

[PrenticeBoyofDerry]

It's to prevent the cable supplying them from overload.
Also the directive given by BS7671 states that only one spur per socket and the number of spurs must not exceed the number of sockets on a RFC.

 

[very_pointy_ears]

Yes I know how to extend the ring, thanks, no problem there.

I've probably got some spare 30A choc block left over too. I'll see how it looks when I lift the socket off to see behind. I'll let you know what I find

 

[slup]

Have you thought about just drilling a small hole and having the PSU for your cat flap in the kitchen, and run the ELV cable through the wall.

It would be a lot less hassle.

 

[PrenticeBoyofDerry]

That's a good point, are these type of cat flaps not available so they work on batteries?
It's not something I have ever seen installed, where would the plug in flex go and how does this effect the safe opening of the door in regards to the safety of the cable?

 

[slup]

They fall into three camps (I only know about this 'cause I fitted one for my other half last week!).

1) Battery only (cat gets locked out or flap fails to open mode when battery runs out)
2) Mains only (as above if power fails)
3) Mains with battery backup (sensible option!)

For something that has a couple of solenoids in and actuates many times a day, I suspect the battery life isn't brilliant. We bought one of the third type.

Having said all that, the damn cat won't go through it at the moment and it's tied open with a cable tie, but that's a story for another forum I'm sure!

I used a couple of self adhesive cable tie bases to keep the cable in a safe place. It's very thin (bell wire size).