Outside light and waterproof switch on garage wall

[Bluedan]

Hi

I am no expert at wiring, but I can do more than just wire a plug! e.g. I've wired in low volatge spotlights, and spurred power sockets etc.

I have just bought a brand new house with a garage. In the garage is power and lighting, so has a consumer unit with 1 fuse for power and 1 fuse for the lighting circuit.

What I want to do is put 2 outside lights on the wall, but have the switch outside, so that I can turn them on/off without having to unlock garage etc.

I'd also like to add a double power socket outside too, I guess this is the same as adding a fused spur to a normal inside socket?

Can someone offer an explanation, or maybe a more detailed description via email?

Would really appreciate it.

 

[rebuke]

Firstly note that this work would probably be notifiable to your LABC under Part P of the building regs, since it involves work on a special installation (a garden lighting and/or power installation). There are arguments coming from the fact the Part P approved document (which is only guidance, not the law) says that the installation of equipment attached to the outside of a house is only notifiable if there are exposed connections though...

You'd obviously need an appropriate waterproof switch and socket, such as http://www.tlc-direct.co.uk/Products/MK56400.html and http://www.tlc-direct.co.uk/Products/MK56482.html

In terms of power, if the existing power circuit in the garage is a 16A radial (it most probably is, but obviously check), then you don't need to add it as a fused spur etc, just take a feed off the end of the radial (or break in to it at a convenient point) to the new socket. The lighting circuit is the same, just take a feed from the circuit somewhere to your switch, and then a cable from the switch to your lights.

One very important thing though is that the sockets and lighting circuit should be RCD protected - it's quite likely that your garage CU has an RCD main switch, or is supplied from an RCD protected way in the house CU, but you'll need to verify this, and if it isn't, fit RCD protection somewhere...

 

[Bluedan]

Thanks for such a quick reply. Sorry to sound dumb, but just to clarify..

If we take the power socket first, radial circuit meaning that it goes from the CU to the socket and terminates there, i.e. doesn't loop back to the CU as in a ring main? As the CU is at the front of the garage and the sockets are at the back, and I want the outside socket about half way along the wall, do I just break into the cable supplying the existing 3 pin sockets, and take a cable from here to the new outside socket? Whats the best way of doing this, using a junction box, or what other way?? Then its just a case of drilling a hole through the wall, and mounting the new socket outside, and wiring it up etc?

Is it ok to fit a double socket, it won't overload anything? I will check to see if the CU has an RCD, I'm pretty sure it does. Will this have to have a certain rating? If it does then I assume I won't need a socket with in-built RCD, or one of those plug in types?

An idiots guide is what I need!

 

[Bluedan]

When installing the socket to the outside wall, how do you create a seal between the wall and the back face of the new socket? Is it advisable to drill a larger hole thru the wall and run a length of tubing/pipe as a conduit for the cable?

 

[wingcoax]

Conduit can be used, also silicone sealant or mastic.

 

[ban-all-sheds]

do I just break into the cable supplying the existing 3 pin sockets, and take a cable from here to the new outside socket? Whats the best way of doing this, using a junction box, or what other way??

Normally it would be best to take the cable from the CU into the new socket, and then out from there to the existing one(s), but this might make sealing the cabling harder, so on balance I'd say that a JB was preferable, as you could then use round profile cable to the socket.

Strongly recommend MK Masterseal sockets, BTW.

How is the circuit inside the garage wired? Twin & earth clipped to the walls?... plastic or metal conduit with singles inside?...

Then its just a case of drilling a hole through the wall, and mounting the new socket outside, and wiring it up etc?

qv.

Is it ok to fit a double socket, it won't overload anything?

It'll be fine - can't overload anything as long as the existing circuit is properly wired.

Is there an Electrical Installation Certificate for the garage CU and circuits?

I will check to see if the CU has an RCD, I'm pretty sure it does. Will this have to have a certain rating? If it does then I assume I won't need a socket with in-built RCD, or one of those plug in types?

Yup.

An idiots guide is what I need!

//www.diynot.com/forums/viewtopic.php?p=75416#75416

When installing the socket to the outside wall, how do you create a seal between the wall and the back face of the new socket?

It's very difficult to do that - water will get through the smallest of holes.

If you can it's always preferable to go in from underneath, with a drip-loop in the cable, which should then run at an angle upwards as it enters the building. With a drip loop and a compression gland on the bottom of the socket you'll be fine (hence the use of round cable). You could also use flexible conduit glanded into the bottom of the socket enclosure, again with a drip loop.




This would give the cable mechanical protection and would mean that you could seal around the conduit through the wall and not the cable which would make wiring changes easier in the future.

I'm assuming, BTW, that the area where the external socket will be is not one where you'd need particularly robust mechanical protection, such as metal, or metal-lined pliable conduit, or armoured cable? If not then tough rubber sheathed, with or without flexible conduit, should be fine for the short length exposed under the socket.

However - you could also look on this as an opportunity to have a go with armoured cable, properly glanded into the socket housing. See //www.diynot.com/wiki/electrics:swa-gland

 

[Bluedan]

First of all, thanks for all the replies.

Why would it make it harder to seal with 2 cables? I was planning on taking cable straight thru wall and into the back of the socket, so it looks neater, rather than seeing the cable come out of the wall then go into the bottom of the socket. There's no problem doing this I assume, as there are the knockouts on the socket to do this.

Looked at a few sockets, and I there seems 2 types, ones that are watertight when shut, but not whilst being used, and ones that are waterproof even when something is plugged in. I assume the latter is for things like water features that are always plugged in, and the former for the occasional lawn mower, strimmer, radio to annoy neighbours on sunny days etc! If so this is personal preference I guess.

From a wiring point of view, to run from the CU, then into socket 1 (which will be the external weatherproof one), then out of socket 1 to socket 2 (inside garage, existing) etc, there is no real difference by running from CU, then splitting this by using a JB, one cable going to socket 1, and the other cable going to socket 2...?? The only advantage I guess is that one method you would have 2 cables going in, and the other method you only have 1.

Garage is twin and earth clipped to the walls, which runs around the garage at the height of the CU quite high up, but then the vertical parts are in plastic conduit where they drop down to either the switches or the power socket.

qv???

As it is brand new house, then not sure if there is separate certificate for wiring or not??

I checked the CU in the garage and it doesn't have RCD's. I am guessing then, until I check, that the garage CU is wired from the main house CU and has an RCD in there. If so, would changing the fuse in the garage to an RCD be over the top, and uneccessary? Are these easy to change, and what would I need?

Is it just twin and earth but formed in a round section instead of the usual flat?

Socket is just going to be on the wall, doesn't need any special protection.

[/quote]

 

[ban-all-sheds]

Why would it make it harder to seal with 2 cables?

That was on the basis of the cable going into the bottom of the socket enclosure - you can't get 2 cables into one gland.

I was planning on taking cable straight thru wall and into the back of the socket, so it looks neater, rather than seeing the cable come out of the wall then go into the bottom of the socket.

It's harder to seal it that way. With cables entering the bottom gravity does 99.9% of the work.

There's no problem doing this I assume, as there are the knockouts on the socket to do this.

You'll probably find that the maker no longer guarantees the IP rating if you use the rear knockouts.

If the wall is nice and smooth then you'll probably be able to get a pretty good seal if you bed the whole thing into a layer of silicone. Make sure you open up the drain holes in the bottom of the box though, just in case.

If you want the best in appearance you can get flush boxes for Masterseal accessories - more work to install, of course, but they do look neater and you've got a bigger surface area to take silicone sealant, and the cable entry holes won't be in the direct firing line of the rain.

Looked at a few sockets, and I there seems 2 types, ones that are watertight when shut, but not whilst being used, and ones that are waterproof even when something is plugged in. I assume the latter is for things like water features that are always plugged in, and the former for the occasional lawn mower, strimmer, radio to annoy neighbours on sunny days etc! If so this is personal preference I guess.

Masterseal are well made, as well as remaining IP rated with a plug in. Their other products may have gone off the boil, but if you were to do a poll here I'm sure they'd come out #1.

From a wiring point of view, to run from the CU, then into socket 1 (which will be the external weatherproof one), then out of socket 1 to socket 2 (inside garage, existing) etc, there is no real difference by running from CU, then splitting this by using a JB, one cable going to socket 1, and the other cable going to socket 2...?? The only advantage I guess is that one method you would have 2 cables going in, and the other method you only have 1.

Fewer cables through the wall means a smaller hole, but if you're going in through the rear then you won't be using a gland and the 20mm KO will take 2 cables anyway.

I guess you could chip out a recess in the wall to allow a gland to be fitted though - then you could use flexible conduit through the wall and up to the level of the cables.

qv???

Quod vide.

As it is brand new house, then not sure if there is separate certificate for wiring or not??

There should be a certificate for all of the wiring, including the garage - that will confirm that the garage circuits were properly done.

I checked the CU in the garage and it doesn't have RCD's. I am guessing then, until I check, that the garage CU is wired from the main house CU and has an RCD in there.

Let's hope so.

If so, would changing the fuse in the garage to an RCD be over the top, and uneccessary?

Have you really got fuses in the garage CU?

Anyway - whatever you have you don't change them for RCDs. RCBOs possibly, but RCDs don't provide any overcurrent protection. If there is RCD protection upstream in the house CU you don't want a 2nd device in the garage CU.

Are these easy to change,

Depends on the design of the CU, and what device(s) you want and can get.

and what would I need?

Appropriate device(s) and to notify your LABC in advance.

Is it just twin and earth but formed in a round section instead of the usual flat?

Is what?

 

[Bluedan]

Thank you ban-all-sheds, very helpful, and great full answers!

just to claify your questions...

Have you really got fuses in the garage CU?

I didn't mean to say "fuse" in garage, I meant to say MCB's. If I do have an RCD in the house CU supplying the garage (positive there is) then this is enough for the sockets in the garage, no additional RCD's needed??

Is what?

I meant to say the twin and earth cable is the same, just one type has a round section and the usual grey type is flatter.

As for wiring, there is no problem doing either methods?


Now let me get onto Question 2!

What I want to do is put 2 outside lights on the wall, but have the switch outside, so that I can turn them on/off without having to unlock garage etc.

Where do I break into the exisitng lighting circuit? The current cable comes out the Garage CU then into the garage light switch, then onto another switch then onto the light I think. Would I spur into the cable before the first switch, and go to the outside switch, then onto each outside light?

 

[ban-all-sheds]

I didn't mean to say "fuse" in garage, I meant to say MCB's. If I do have an RCD in the house CU supplying the garage (positive there is) then this is enough for the sockets in the garage, no additional RCD's needed??

Yup - if you've got one in the house CU, and it protects the MCB supplying the garage CU, then not only is there no point to having another in the garage, it'd actually be against the Wiring Regulations.

If there is no RCD protection of the garage you should have strong words with the builder/company that sold you the house.

I meant to say the twin and earth cable is the same, just one type has a round section and the usual grey type is flatter.

All twin & earth is flat, whatever colour it is.

As for wiring, there is no problem doing either methods?

If you can get two cables into the socket then do that rather than introduce a JB.

Where do I break into the exisitng lighting circuit? The current cable comes out the Garage CU then into the garage light switch, then onto another switch then onto the light I think. Would I spur into the cable before the first switch, and go to the outside switch, then onto each outside light?

That would probably be best, as the cable between the two switches may not carry a permanent live.

You should study the info here: //www.diynot.com/wiki/electrics:lighting and learn how lighting circuits are wired.