External socket for providing power to camper van.

[David WE Roberts]

I've looked through the Wiki on taking power outside and read the bits about single external socket on an existing ring and RCD protection.

I can't immediately find anything about installing the single external socket.

What I want to do is to put a female blue round pin outlet with a spring cover and pointing downwards (just like you get on campsites) on an external wall near to an internal 13A socket so I can take a spur through the wall.

This to replace the current arangement where the cable goes through a partly open window and has a [round pin 13A] adapter to plug into an internal socket.

The sockets themselves look reasonably priced, e.g.

this is the sort of thing I should be using.

As far as I can tell I have only MCBs (MEM M6) in the fuse board and a single whole house RCD so presumably I will have to add an RCD to stop the whole house tripping should there be a problem.

Plan is therefore roughly to install a switched spur internally incorporating an RCD, take a cable through the wall and into the back of an external socket. Interesting part may be sealing the back of the external socket to the wall as the wall is a sharp shell pebbledash.

Oh, and if I do this in the (very long) kitchen/diner in the diner part is this something that falls foul of Part P?

Cheers

Dave R

[The Natural Philosopher]

not sure that's appropriate - aren't the blue sockets more amps than

13A? all I did was get waterproof 13A sockets for outside, and spur em off the inside by drilling through the wall.

RCBO is better. replaces the MCB.

lots of favorite goo. Hot glue, mastic, silicone, car body filler...

I pee on part P.

Who honestly cares?.

[Jim]

The blue sockets are rated to 16A.

Not that that particularly matters. We have been running a caravan from a 13A three pin plug for 14 months without blowing any fuses.

[Toby]

Problem here is, the normal caravan sockets are only rated to 16A, and your ring main will be potected to 32A - you either need to install a new circuit back to the consumer unit, and protect it at 16A, or supply it from the ring, via a FUSED spur, fused at 13A (I guess you won't be drawing more than that in the van?)

Sounds sensible.

assuming this is the sort of thing I should be using.

If you do that, then you will have two RCD's the main one being more loaded would probabaly still trip first. Unless your cusumer unit is a split type already, which you say it isn't, you will need to either replace the existing one, or add another consumer unit with either another RCD, or preferablly a main switch and an RCBO, plus some spare ways for future use.

As I siad before, if the ring is already on an RCD, this second one is pointless.

I would make sure the hole from the inside to the outside slopes downwards slightly, so water cant flow into the house, put the cable through and then squirt silicone seaent in the hole, once this is set, mount the backplate for the blue socket, and then seal this on the inside with more silicone, then wire it up once this has set.

The other option, is to install a single waterproof standard socket directly to the ring, then keep the adaptor, but it would then be plugged in outside. - One that still seals when in use, like the MK ones here

> Oh, and if I do this in the (very long) kitchen/diner in the diner part is

Probabaly

[Dave Osborne]

OK.

Yes.

You could add a local RCD, except that there will be no guarantee that the local RCD will trip in preference to the whole-house RCD.

If you supply the spur from a ring main, then the ring main is going to need an rcd anyway, so you are always going to have a discrimination problem if you use a local RCD unless you pull in a radial circuit just for the outdoor socket from a non-rcd-protected MCB in the consumer unit. Except that you don't have any non-RCD protected ways in the consumer unit. ;-(

So, either you would need to change the consumer unit for a split-load jobbie, or add Henley blocks and a second consumer unit, or you would need to change the whole-house RCD for a main switch and then change some of your MCBs for RCBOs.

If you did any of these, you could (if you wanted) ditch the RCD spur and have an RCD in the consumer unit.

OK, but you would need to ensure that the RCD spur is fused at 13A.

Use flexible cord 1.5mm2 to connect the spur to the socket outlet. Drill as small a hole as possible in the back of the socket. fit the cable to the socket. Seal up the hole with flexible silicone and then fit the whole assembly to the wall. Finally, terminate the flex to the spur.

;-)

[The Natural Philosopher]

go for 100mA main trip in the house, and 30mA RCBO's where needed.

>

[Andy Dingley]

Needs protection for that circuit alone (it _might_ not, but probably will). This is most conveniently obtained through a packaged solution in one IP-rated box that can screw directly to the outside wall. This also puts the RCD test button and the overcurrent reset on the outside, where you can get to them most easily.

[Dave Plowman (News)]

I take it you want to use a 16 amp BS socket like camp sites so you can use an existing lead? I'd give some thought to using a 13 amp one as it can have other uses. And weatherproof combined 13 amp outlet/RCDs are readily available.

[John Rumm]

Installing the sockets itself is usually straight forward if you can drill straight through from the back of it.

Yup, that's ok.

> assuming this is the sort of thing I should be using.

Yup possibly. You can also get posher versions with RCD protection.

No. You need to check the trip threshold of the RCD you have. If its

30mA or lower, and it does indeed cover all the house circuits, then you can dispense with the need for further RCDs. Note however that any dampness getting into the exterior wiring could make trips more likely in the house. To mitigate this you could ensure it is fed from a dual pole switched fused spur inside, so that you can disconnect it if there is a problem (or when power outside is not required).

Adding an additional RCD will do nothing useful - you just have two places to check and potentially reset if you do get a trip (cascaded RCDs don't discriminate)

Yup, but without the RCD, unless you can supply the spur from a dedicated non RCD protected feed[1].

Silicone is your friend. A small hole in the bottom of the socket can also let any water out that gets in.

I would assume its in the dining room and hence ok:

(not that I would give a toss if it were in the kitchen either! ;-)

[1] With "whole house" setups that becomes difficult. You either need a replacement CU, or a supplementary CU from split tails as per the wiki article. Personally I have all external circuits and sub mains etc on their own dedicated CU, completely separate from the house ones. Saves bringing faults in from the cold!

[Toby]

John,

Is it OK to feed a 16A socket from a 32A ring?

I assumed not, seen as there isn't a fuse in the blue plug or socket!

Toby...

[Owain]

Yes, but you should have 16A MCB on the spur for overload protection, because the 16A plugs are unfused.

Owain

[Dave Osborne]

The IEE Wiring regulations don't cover this situation for domestic ring final circuits.

The basic principle is that you fuse (at the consumer unit) to protect the installed cables, as fire caused by overheating in installed cables (not electric shock or anything else) is about 90% of the risk in a fixed electrical installation.

At the point where you connect the socket outlet to the installed cable, you have to consider the continuous current carrying capacity of the plug/socket outlet and the breaking capacity of the plug/socket combination.

In the case here, the continuous current carrying capacity is 16A and the breaking capacity is 125% of nominal or 20A.

In a domestic environment I would consider any of the following: -

1. A 16A radial circuit supplying one or more 16A socket outlets.
2. A 20A radial circuit supplying two or more 16A socket outlets.
3. A 32A ring final circuit supplying a 13A fused spur for each 16A socket outlet.
4. A 32A ring final circuit socket supplying one or more outlet combi boxes[1] with local provision for 16A MCBs.

[1] e.g.

[David WE Roberts]

Thanks for all the input. I assume this is similar:

is also over £100 and so is slightly OTT for my simple domestic needs. The 13A fused spur sounds the best option as it replicates the current more informal arrangement with the 13A plug and adapter. Double pole fused switch to allow it to be turned off from indoors is also good - this would be essential if the socket was on the front wall to prevent someone 'borrowing' electricity when we were away. I am still slightly puzzled by some of the Screwix listings as they sometimes seem to list what looks like the same thing from the same manufacturer at slightly different prices.

Is there scope for a specific Wiki entry for all those caravan and camper owners who keep their outfits at home?

Cheers

Dave R

[Tim Watts]

> It is also over £100 and so is slightly OTT for my simple domestic needs.

The IEE 17th regs do not approve of unshuttered power sockets (or specifically they only approve a few particular BS standard sockets that happen to all be shuttered) in a domestic installation (I will find the reg reference if you'd like proof).

However, I would say that use of the interlocked socket would meet the spirit of the regulations (ie cannot have live holes) - ie I would be totally happy to justify that to the face of a BCO, NIC inspector or anyone else.

100 quid sounds expensive. Lets look:

?rvr_id=&rvr_id=&cguid=cd9d48e81270a0e20535a635ffd2f75c(Gewiss is a good make BTW)

you don't use one of these, I would suggest at the very least mounting it high, out of reach of kids.

Obviously, you *must* have it RCD protected (30mA/40mS - standard RCD) as it is feeding outside.

As others have said, you get no guarantees with cascaded RCDs unless the head end is a time delayed type used on TT supplies.

However, with a double pole isolator it would not be dangerous to rely on the house RCD - just inconvenient if it trips, which IME is rare enough to live with if the alternative is impractical. At least make sure you can isolate it on both poles, preferably from within the house (eg at the fused spur) because if it does get full of water you will have a means to restore the rest of the house power.

On the subject of a 13A fused spur - perfectly OK and approved to do this (this is even mentioned in the IEE Wiring Matters magazine for a whole shed supply as a possibility. You are underfusing rather than overfusing a 16A socket, so the worst that happens is the fuse goes. Not dangerous. Incidently, you'll pull 16A through a 13A fuse for quite a long time before it blows. But for your setup I doubt you will get anywhere near that.

BTW - I've been through the theory because I fancy a couple of these under the soffits on their own 20A combined RCBO feed.

HTH

Tim

[Chris J Dixon]

That must be some Xmas display you are planning ;-)

Chris

[Tim Watts]

Hmm. Animated neon of Rudolph and Santa...

"Daady - Santa keps trying to jump up onto Rudolph and he can't manage so he's trying again"

"Err I don't think that's what he's doing son..."

Or a massive laser display onto the clouds :)

[js.b1]

Couple of comments,

#1 exporting PME (TN-C-S) to a caravan may upset the DNO, however since it is a camper van I do not think it is perhaps practical to do a local earth rod since by its nature the van is somewhat mobile (unless it is essentially stationary?).

#2 You can get interlocked sockets cheaply online such as the compact IP55 Geweiss unit at

& from Ebay too.

#'3 Do you really need a BS4343 outlet, most likely interlocked, on the side of the house? Why not use an MK Masterseal 13A socket (usable with everything), and make up a simple lead with 13A plug on one end going to BS4343 inline-socket on the other with a BS4343 appliance- inlet on the caravan? You can use the outdoor socket for anything.

Cable can enter the rear of an MK socket via their special backbox - it has no top/side knockouts and instead has a single rear hole that takes MK's own 20mm conduit grommet. The conduit is used to sleeve the cable through the wall. As for pebble dash, use long screws with small plastic spacers (check Ebay, various diameters & depths) which will standoff the socket from the wall yet mechanically retain it via all 4 fixings.

Interlocked BS4343 tend to be quite big ugly beasts, the Geweiss compact unit is an exception but still about "a foot".