Just a quick question to any electrical experts in here.
I want to put a plug socket in my loft, but i'm not sure where to take it from, as there are no ring main power cables up there, only lighting cables. There is however, the enormous cable for my shower!, (10mm T&E I think) which i'm sure could easily supply a single power socket. The thing is, I can't seem to find a junction box to take this size cable (well, not at B&Q, Wickes etc.), although I haven't tried a merchants yet. Also, is this the right way to join to a cable this size, or indeed, is this meant to be done at all (i've been told, not by an expert mind, that you should never run anything else from a shower cable, only the shower). The shower is 9.5 kW, so the 10mm cable must have plenty left for a power circuit, i'd have thought). I guess the alternative is to take a spur from a socket in one of the bedrooms etc., but I don't want to upset any decorating. I just want to locate a suitable source already i the loft.
Perhaps i'm going about this all the wrong way, if so can antone suggest anything else (from the available cables in th loft).
I'm aware of the changes to wiring regulations recently, but not sure if this applies to what I want to do, if so then I'll get someone qualified to do it.
No. Lighitng circuit rated at 6A. 13A socket rated at 13A. Also, if your house has TT earthing, the lighting circuit might not be protected with a 30mA RCD, which is required for sockets on a TT installation.
That is correct.
Not much. A 9.5kW shower is 39.5A; 10mm cable is rated 43A in thermal insulation, which may be the case in the loft. That is *without* correction for ambient temperature, which may well require a derating factor in a loft, of perhaps 0.71. So your 10mm cable may actually be under-rated for the shower.
Don't you have any fitted cupboards you can take a cable up inside? Provided it is not in an area subject to physical damage and is visible, surface clipped cable is perfectly acceptable in a domestic installation. Take it neatly along a skirting board and up a doorframe, then through a neat hole drilled in any cornice, and leave some slack at each end, so that the cable can be concealed when the room is next decorated. Even taking it up the side of a window can mean it is concealed by floor-to-ceiling curtains in some cases.
Personally I wouldn't interfere with the shower feed in any way. You don't happen to have a socket in an airing cupboard do you ? They used to be a common feature.
On Tue, 31 May 2005 16:49:50 GMT, graham strung together this:
Er.....
No, no and thrice no. Don't do it, full stop.
Correct, don't do it.
Stop thinking, it's ot going to do any of us any good. "Assumption is the mother of all f*ck ups".
Not so much an alternative, as the only correct way to do it. You must have a cupboard or wardrobe somewhere with a socket behind it or backing onto it. You can easily drill through from a suitable socket, up through a cupboard and into the loft to a socket. If not, just whack a length of trunking up the wall as a temporary job and sink it in the wall next time you decorate that wall.
Minor nit, but the RCD for protecting all socket outlets in a TT system does not need to be limited to 30mA (it isn't there to protect against electrocution).
Regulations wise, if it comes from the bathroom, I believe Part P covers it and it must be installed by an electrician. However, I don't believe any electrician would take it from your shower feed. Would it be difficult just to take a channel up a wall and into the loft from a wall socket and then plaster/paint/paper over it?
AFAIK, you shouldn't use the lighting circuit at all, as even if you don't, a future person could attach something of high load and cause a fire.
I'm no electrician though so I'm sure there'll be a flood of answers from those who are soon enough ;)
But any load higher than 5 or 6 amps would trip/blow the lighting circuit's MCB or fuse, so I can't see how it would be dangerous ? That's not to say it's reg-compliant ! The only safety issue (ignoring the regs etc) would be the possible lack of RCD protection.
Maybe.. But not straight away, they take time to trip and even when they do the chances are the cable has heated up considerably. So if a future home owner does this on a regular basis he may damage the cable by heating it too much. Eventually you'd get a short which may not instantly blow a fuse (say if it's been replaced with one of the wrong rating to stop it blowing!) and then you get your fire.
Another reason I think this may be a bad idea is if you get a novice DIY-er who wishes to say install a double socket, he goes to his CU and switches off the ring marked 'upstairs plugs' or whatever. So when he thinks it's dead... It may not be. Same may go for a shower spur too.
Of course this is all hear-say by me who's electrical knowledge is non-professional.
Yes, I'm not advocating leaving such an arrangement for any future house owner, such a thing should obviously be removed if you sell the house, but for one's own use, under your own control etc, I see nothing wrong.
Of course should your house burn down due to a totally unrelated cause, and the socket connected to the lighting circuit is found by investigators, it might well invalidate your insurance claim. :-)
Run it through a fused connection unit with a 5amp fuse, thus there are 2 fuses protecting the socket. yes some could uprate both fuses - but then again someone could re wire the socket completely.
That's true enough. Still not the best thing to do. If a wiring inspection were done when you go to sell, I'm sure it would be pointed out as a "fault".
Take a feed from an appropriate circuit. An appropriate circuit is one wot's got other sockits onit. Not the shower, not the light. Either one of those risks overloading the cable - and for those who believe that an MCB rated at 6A will instantly blow if you pull 6.01A, 6.1A, or 7A - no, it won't. It'll let 9-10A pass for 15-20 minutes at least. *If* you're lucky, the lighting cable's 1.5mmsq and can dissipate heat easily, so drawing 9A (full lighting load + 1kw fan-heater warming you in the loft) won't matter at all. If it's wired in the more normal (and cheaper, so bound to be used in any mass-built house) 1mmsq, and passes through good thick thermal insulation for any substantial part of its run, it'll warm up good and proper. No, it won't burst into flames; yes, the PVC insulation *will* soften, and anywhere there's a bit of pressure on it or a bend in the cable, the softened insulation *will* flow slowly away, leaving bare conductors if you're unlucky.
How are you for black cats and paired magpies?
Similar thought tells you why putting a 13A socket on your shower cable is a no-no. Again, the cable and MCB/fuse have been sized for the shower you have (or for the shower that was initially installed; possibly replaced later by a higher-current model). If the shower's a dinky little 7.5kW job (draws 31A), and it's wired in 10mmsq because that's what the sparks had on the van that day, and it takes a thermally-kind route - no practical problem. (Still a Regs violation, of course.) If the shower's a 9.6kW job (40A), run on a 6mmsq cable which was OK for the previous one which a handyperson's replaced with the new whizzy model, running through thermal insulation so it's already running at or over the sustained-temp limit of 70 degrees, with a 40A or 45A MCB fitted by the same handydroid to Uprate the shower, and you fit a 13A socket on it, wh'appen when it's *really* cold oop in t'loft and you wind the fanheater up to 3kW, while someone else takes a shower? The current's now up to 52A. Your 40A MCB doesn't mind, it can pass that current for hours; your cable's insulation, on the other hand, is now enjoying new heights of devil-may-care flexibility...
Y'see, the Regs is written to reduce - not eliminate, reduce - the need for detailed analysis, and so that almost all foreseeable installations which conform with them are safe in practice, in normal use *and* under fault conditions. Going beyond the envelope of the Regs puts you in territory where you *may* still be lucky, or you *may* not.
Again, how many rabbit's feet do you have to hand?
There's plenty of ways of arranging a 'temporary' safe-enough feed up to the loft, which others have already outlined - if it's genuinely occaisional use, a flex running up a corner of some room or up a built-in wardrobe or airing cupboard up to a 4-way extension block which you plug in to a handy-enough socket is safer than fannying about with putting 13A sockets on lighting or (shudder) shower circuits. Doing a surface run of cable as a spur - again, taking some aesthetically-acceptable route - with a good length of slack up in t'loft ready for when you next redecorate and can sink the cable properly into the wall, or run it through the studwork wall if that's how your place is built, is a fully Regs-conformant solution. In short, there's enough ways of doing the job properly which don't require wall butchery at an inconvenient time that there's no excuse for bodgery...
But will an FCU with a 5amp fuse blow as soon as 5amps of current is drawn through it? I'll bet it wouldn't, and an MCB is unlikely too until the circuit has been loaded for some time (unless you can get really quickly reacting ones). An RCD would not protect against over current here either, it'd only help if a fault were to arrise but the damage would already be done then...
I personally don't think there is a great need for a socket in the loft, after all what could you need to run up there when you are not up there with it and can therefore use a drum extention lead.
The only things I've ever used in a loft is a lamp, soldering iron and a power drill... All powered from an extention lead. I guess it's convinient but I'll bet the OP has an extention lead he can use anyway.
fine for occasional temporary use, not so good or convenient for longer term or frequent use.
Whereas I have an aerial distribution amplifier, 4 computers, a monitor, a KVM switch and a network switch permanently up in the loft. 2 double sockets come in very handy up there.
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