First off I have only ever wired a plug before so any advice you give me will have to be REALLY simplified, sorry. Anyway...
I am trying to run an electric supply to my stone outbuilding. I have bought a kit with all the armoured cable, RCD plug, waterproof socket, junction boxes etc etc. The instructions are ok & I am following them but I have a question...
Each end of the armoured cable has a junction box to connect it to flexible cable. Does this have to be so? Can the armoured cable be terminated directly at waterproof socket? Can the armoured cable go straight into the RCD plug?
The placing of the socket inside the house means that (if possible) this would be the easiest way- bypassing the whole junction box wiring bit.
Thank you & apologies for my knowledge-free language LOL!!
Depending on the design of socket you may be able to take it directly to that, however you are unlikely to be able to take it directly to a plug (the SWA will be way too big). SWA cable normally needs to terminate at a gland that correctly clamps cable screen - this is particularly important where the screen is being used as an earth connection (usually with two core cable).
Inside the house or the outbuilding?
If the socket will accept a 20mm SWA gland then you may be able to do it that way, however it is hardly any more difficult to use the supplied box is it?
Well, no. Guy's got a point. There are situations where exporting the house earth half way down a garden might be considered dangerous. Your plug kit makes it a bit too easy and you won't question such things, as you might if you had to go to the trade shop and buy all the bits separately, because you would either have read up in order to know what to buy or the trade bloke may offer some advice. I'm not an engineer so I won't elaborate on this further.
Please read this:
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a pretty decent guide to external power supply provision.
Personally, I'd say screw Part P and just learn how to do the job correctly (start with the above).
Be aware there's a fine for that if you get caught in 6 months and you could get sued if you kill someone and it might affect your house sale.
If you're not confident, get someone to inspect it. Coughing up 100 quid for Part P may get you an inspection, or it may get you a council bod coming round going "looks alright [tick]" (seen reports of this happening). Think if it were me, I'd pay an electrician to PIR it, at least the inspection will be done thoroughly, if not by the book of stupid rules.
Thing is, the biggest worry with external supplies are the earth (local TT or export house earth???, the protection (RCD) and the bonding requirements of the building (steel garage???)
Buying a kit with a plug makes the job technically legal, but does not address those concerns properly IMO. Especially if someone chops the RCD off when it breaks and sticks a normal plug on.
Yep, bought a kit comprising a "Powerbreaker" waterproof exterior socket= ready wired to a couple of meters of ordinary flex and a RCD plug. Princely sum of =A319.99 + VAT from Makro. The waterproof socket is very= MK like, plugged in cable seal is very soft squidgy rubber.
Talking of which, taking the whole thing logically further:
Simply install two 63A "commando" single phase sockets (with suitable circuit protection) by the meter. Get this done by the book or pay a sparks to do it. Or maybe one 3 phase 63A socket with suitable supply for neatness...
Now you are free to plug your whole house in[1], thus making it an appliance and exempt from Part P worries...
[1] Couple of CUs or one 3-phase board, with a flying plug etc...
Total bollox? Probably - but not very much different to these kits. There's a marketing idea - the "whole house rewire kit" as sold in B&Q :)
Cheers
Tim
PS
Sorry - I can't claim credit for the above, someone thought of this last year...
PPS - we are actually doing the 3-phase/63A socket thing at work, for temporary computer room power when the submain distribution boards are being worked on. There will indeed be a 3 phase plug feeding a temp distribution board feeding a load of flying 32A single phase sockets. All approved and being done by pros... Temporary in this case means 24-48 hours mind...
At least you're not doing what a firm I worked for did. Portakabin arrived, couldn't be bothered to wire in properly to the fusebox so for a "short term" solution they made up an extension lead with a 13A plug on each end and covered the one in the Portakabin with lots of gaffer tape once it was plugged in.
I am sorry if I came across as a complete idiot with my opening post- I have been doing lots of research about this before undertaking the project. I am actually a PC hardware technician so do have some understanding of circuits etc. I understand the reasons for Part P legislation & do agree that it should be in place. I don't believe I have done a 'bodge job', & I am glad there are people who are ready with useful advice. There is no way I would have considered doing it if I felt less than confident.
The 3-core PVC cable runs from the house socket (through an RCD plug) to a waterproof junction box outside the house. Then armoured cable then runs to a stone outbuilding next door (the 20m of cable is clipped to the wall). The arnoured cable is terminated directly into a waterproof socket inside the outbuilding. All the connections I made were obvious & clear & done correctly.
I can't see why this would cause any problems, or (G forbid) death. I assume someone can tell me where I have gone wrong????
PS It works great & we will see if the RCD trips (there is only a light running from it)
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> for a pretty decent guide to external power supply provision.
On 17 Jul 2006 04:59:07 -0700 someone who may be "spiralpromo" wrote this:-
A search engine should pull up a posting that explains the differences between electronics and "real world" electricity.
I'll add one thing to this. Twice someone of an electronic background has asked me how many milliamps were drawn by something. In one case the bit of equipment was connected the supply via cables over centimetre in diameter, so I would have thought that even the meanest intelligence would be able to work out that this was many hundreds, if not several thousand, amps one hour rating. In the other case the boffin was very surprised to discover that around
12,000A would flow, if someone connected the two wires together, in the very short period before the HRC fuse did its job.
Supplies to outbuildings are best done properly, ie not through a plug and socket. That is why Mr Prescott's stupidities (in England and Wales) are rightly treated with contempt by anyone other then party politicians and officials.
Such a sub-main should be installed properly and the article you have already been pointed to is a good starting point.
20m of cable implies that the outbuilding is around that distance from the house. I would certainly need to consider the situation very carefully before exporting a house earthing system that sort of distance to another building. 1/10 of that distance, even 1/4 of that distance and it would be an easier decision.
You need to understand, amongst other things, the limitations of RCDs. The idea that one can bung such a gadget in and everything is fine is promoted by their vendors, but that doesn't mean it is correct.
OOps. Perhaps I should also have said that I have a physics degree too (not that that is anyway comparable to 'real world' electricity & sparkies- just that I do understand amps, watts & volts etc.)
The building is directly next door- (as the crow flies the sockets are only 5m apart. In fact if I could drill through the wall separating the bulidings they would be about 1m apart. 20m (probably over-estimated actually- nearer 12m) is only needed to run it neatly & safely past the downpipe)
No, I definitely understand this & am not putting all my faith in it. I won't be running anything other than a lamp from it (certainly no kettles, heaters etc. etc.) You are right that a lot of people think they can forget safety & will be protected by this gadgetry.
I am fast wishing I hadn't placed this post. My desire for light in my workshop has given people a chance to vent their spleens about people bipassing P-part legislation. Not everyone does a poor, unresearched shoddy job. I am sure the best thing for me to do WOULD be to get a fully qualified person in to do it for me, but at the end of the day I didn't. Sorry. Thanks to all those who helped in my search for help & not damnation ;)
That doesn't actually make any difference. Not using any portable appliances would make a difference, but a 60W handlamp will electrocute you just as well as a 3kW heater, and the shortcomings of the RCD will be the same in each case. Actually, the heater is likely to be safer, as it should at least be earthed whereas the handlamp is probably double insulated, so a fault on the heater should cause an immediate RCD trip while the handlamp can sit there all nice and tingly-live waiting for you to pick it up.
On 17 Jul 2006 08:16:31 -0700 someone who may be "spiralpromo" wrote this:-
That is even worse:-)
Stories of people with a scientific bent doing mad things with electrical wiring are legion. Some may even be true:-)
What is the reason that you can't? Could a cable be routed under say a path between buildings?
I take it that it is not going to be attached to a fence. You mentioned a wall in an earlier posting.
The problem is that a desire for a light tends to soon become, "while I/you are at it couldn't I/you just..." Thus it is worthwhile getting it right and allowing for future expansion in the design.
Part pee is rightly criticised here because it does nothing to prevent shoddy jobs. It is simply an indication of the ridiculous approach taken by administrators who know nothing about engineering. They are only interested in having boxes to tick. Safety might be the claimed goal, but that claim is a bogus one, as the CORGI con demonstrates eloquently. Instead of learning from that blunder administrators continue as if everything they do is perfect.
The walls are ridiculously thick as its a very old property (probably
1.5m thick judging from the window recesses) I don't feel confident about what I would be drilling through. There is a hole out of the front of the house already (from a previous aerial) which I am using & routing it straight along the stone wall into the connecting building next door. It doesn't go along the floor at all (its clipped into a U shape to avoid an awkwardly placed downpipe). (Its more of a really old extension/stone lean to, & is physically connected to our house. I wonder if people think I am trailing a cable down the garden??)
Oh no, I'm not going there ;) I only want a lamp in there- that's all. I have no plans for a kitchen extension or anything else. Just a small lamp :(
Yes. There is nothing in this bit I can disagree with- you've got me there. Damn those guys with clipboards!!
Me too. I've also been an electronics technician, now a computer systems manager (still do PC tech stuff as and when). My Dad's also an electrical engineer, so I have *some* grounding in these things, though my knowledge is pathetically dated.
Cons:
1 - People like us are generally very au-fait with low power ELV circuits and sometimes LV in a semi-industrial setting. We can be used to the mindset "Flick the switch, does it work? Job done". We assume all other people are equally conversant with not sticking their hand in the dangerous end of the machine. Problem is domestic wiring is definitely an area where all sorts of initiated types will test your system for safety. (Un?)fortunately, the law of natural selection in the human world is not really an approved philosophy of life.
2 - More often than not, systems we are used to are small and isolated and predictable. High power electrical systems can be subject to all sorts of weird failure cases with unthought of external influences. IET (IEE) bods who write the wiring regs try to think of these things and recommend wiring systems that mitigate common and weird faults as much as possible. They occasionally do stupid things like change all the wiring colours but that's another story...
Pros:
3 - In theory we have at least two braincells, so if we accept our limitations we are in a good position to ask sensible questions and get good advice.
I'll add some comments, but please remember I'm not qualified.
5m sounds OK to export the earth, unless your earth provision is one of a few types (do you know which system you have?). I would feel uncomfortable exporting a TT system (your house makes its own earth with a rod in the ground) even 5m. Better to have a second separate TT for the outbuilding IMHO. TT demands an RCD, but you have that (earth fault currents are often too low to trip an MCB/fuse). TT systems also need testing to prove they are adequate.
Systems where the earth and neutral are combined until your meter ring a bell as being dodgey too in this scenario - but I have no experience of these systems - just flagging up a case that needs more informed opinion.
May be other less common systems too that need special provision.
You have a stone outhouse - so you don't have exposed metalwork? If so that simplifies things. Downside is that your floor is possibly damp with no DPC and a fairly good earth given the right (or no) footware.
All in all, it's better than just stringing a bit of flex overhead (at least the cable has mechanical protection), but not as good as a proper installation. That's just my opinion.
At least you didn't get an ear-full of "get a sparky to do the job" ;->
Personally I think the best way is to learn how to do these things, but get a qualified person to look it over. That way one learns and correct methods are vindicated, bad ones are corrected. In theory Part P aspires to this, but it's a c*ck up implementation wise.
You will tend to find the vast majority in this group will treat part P with the utter contempt it deserves ;-)
I don't think anyone is suggesting that your workmanship will be at all shoddy. The two areas of question are:
Using a plug and flex to connect up what ought to be wired as a proper submain (a choice presumably made by the assembler of the "kit" of parts you bought, with a mind to avoiding the implications of part P - yet another example of how it is counter-productive).
Secondly there is the issue of earthing. If your house has a PME supply (i.e. the neutral and earth conductor are bonded together at the head end of the cable from your electricity supplier), then great lengths will normally have been taken to ensure that all exposed metalwork, pipes, gas and water services in the property are correctly equipotential bonded. One of the reasons for this is that while under normal circumstances PME supplies are very safe, there are some fault conditions where they can leave all of the metalwork in your house sat at 240V. Hence it is important to make sure that *all* of it is well tied together if you are to avoid a serious electrocution risk. If you export the earth from a PME supply then you must also ensure you export the bonding and make the outbuilding a part of the equipotential zone. With some outbuildings (especially those with either a bare soil floor) it can be very difficult to maintain a good equipotential zone in these circumstances. Hence in these cases it is more usual to disconnect the earth between the buildings (only using it for the protection of the cable in transit) and provide a dedicated local earth for the outbuilding (a "TT System". There are further implications wrt to earthing if there is a large distance between the buildings - again which would tend to suggest a local TT system.
Crikey. What a lot of good advice, but you all put the fear of god into me & I have had someone come & check it out. Our sparkie says, yep- all great. The earth issue is fine, the RCD is ok, all the wiring etc etc is exactly as it should be. YIPPEE!!
I have light in my outbuilding & I will never touch another cable again as long as I live. No, honestly I have printed all this off & will read it properly later.
I agree that sometimes (as long as you have a few brain cells & don't attempt the impossible) the best way to learn is to give it a go.
Thanks everyone. I will be certain never to mention the 'P' word again on here.
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