I have looked at the FAQ and there doesn't seem to be much electrical stuff there - mainly a pointer to the wiring regs (or at least, where to buy them).
I am now Googling through but there is a lot of chaff to winnow to find the wheat.
Is the FAQ not populated with wiring answers because of potential legal liability?
Even a few pointers to threads in Google Groups would make life a lot easier.
I will carry on researching, and then post what I think I have learned in the hope someone will be kind enough to cross check.
I have just had the kitchen completely gutted (plaster off walls, ceiling down) and am about to start on minor modifications to the wiring - or at least this is what I thought until I started.
I have 4 * 13 Amp sockets in the kitchen; three doubles and one single which is on the cooker point.
When I (fortunately) checked I found that they were all on different circuits.
One double spurred off the garage. One double spurred off the house 13 amp ring main (with another double spurred off this going into the lounge). One double spurred off a 20 amp circuit which I thought did a complete kitchen spur, but turned out to do an extractor fan and one double socket. [I am still trying to trace where this circuit goes because it is inside the cavity and I haven't yet found where it exits.] One on the dedicated cooker circuit which goes straight back to a 32 Amp fuse.
Fixed(ish) electrical devices to go in the kitchen: (1) Dishwasher (2) Under the counter fridge (3) Under the counter single oven (4) Kick space heater (planned to be a fan and a radiator of the CH but a
2Kw all electrical jobbie may turn out cheaper). (5) Power to the gas hob for the ignition circuit.
On-the-counter devices:
(1) Microwave (combination grill/microwave/oven) (2) Kettle (3) Bread Maker (4) Digital phone handset (5) Hand blender (6) Towcester (7) Possibly another toy or two if the mood takes us.
The other main things will be lighting under a row of wall cupboards, and possibly low voltage lighting inside a glass wall cupboard. I assume these should come off the ring main not the lighting circuit.
My current plan is to install a ring main horizontally above the worktop, with spurs down to the under-the-counter devices.
Much good information has already been picked up.
I think I will retain my cooker circuit as it is in about the right place, although I recognise that I could take it off the ring main as modern cookers are low(ish) power and I don't have an electric hob.
I am undecided about the appliance spurs. The over engineer in me likes the idea of an isolation switch for each appliance in clear view with an unswitched socket inside the units, but I recognise that this is not strictly necessary and can make the wall space look cluttered.
My current outstanding questions:
(1) When you put sockets for the spurs beneath the units, is it necessary to mount them in the wall and then cut a hole in the back of the unit, or can you surface mount a box inside onto the back board of the unit, with the wire coming in through the void at the back?
(2) How high should the sockets be above the work surface?
(3) What is the minimum horizontal distance between a socket and the sink (and is this from the bowl and taps, or from the edge of the drainer)?
(4) What is the minimum horizontal distance between a gas hob and a socket?
(5) Should I run my wiring in conduits - if so is plastic O.K. or should I use metal so that future owners have some chance of locating the wires before they drill in to fit spice racks, kitchen towel holders etc. ?
I haven't done my final sums yet to see if everything will fit on one ring main - I have a few power hungry devices there - but my first guess is that it should be O.K., especially if I put e.g. the combi microwave on the plug on the cooker circuit.
I have 'gained' two 32 amp fuses in my fuse box - with the new combi boiler I no longer need the immersion heater or electric shower circuits.
I've done two kitchens in the last 8 years. In both cases, I installed completely new circuits for the kitchen (except lighting), and replaced the CU's to take the extra circuits.
o 30mA RCD protected ring which feeds all the portable appliances and all easily accessible socket outlets. o non-RCD protected ring which feeds stationary and fixed appliances such as fridge, freezer, washing/dishwashing machines, boiler, oven (with 13A plug). No easily accessible socket outlets, so this circuit isn't used for portable appliances. This would also be a good circuit for something like a fishtank life support system, although I might use an RCD plug if the apparatus wasn't all well double-insulated. o Cooker circuit. In both kitchens, a gas cooker is fitted so this wasn't needed, but it seemed silly not to make provision for an electric cooker in the future. Outlet fitted with a 13A socket for now so hob ignition can be powered from it, but it's in a deep box and can be replaced with a high current flex outlet. o Lighting -- at least two separately switched sets of lights so that lighting level can be adjusted (without using dimmers). Split into general room lighting, and worktop task lighting. For task lighting over a sink, I used a pullcord switch fixed under a nearby cupboard with a 4" string, so it's perfectly safe to operate with wet hands.
Sounds like it could all do with a radical pruning and starting over.
OK, that lot does not sound too bad. Many of the smaller appliances are short term loads anyway (kettle, toaster etc)
You can do either. If coming off a power circuit then you will need additional fusing at the point you take the lighting feed usually.
They could be switched feeds in some cases rather than spurs.
Do you need to power a cooker? A free standing gas cooker will only need power for ignition and clock etc, so not a big load. Even a single electric oven can be powered from a general purpose circuit.
You want to make sure you have a way of isolating each appliance without having to pull it out. This can mean above counter switches, or sockets that are accessible in adjacent cupboards for example.
It is preferable to have fixed wiring fixed to the building and not the furniture. However you can use common sense here. Sometimes surface mounting (or using a drywall mattress) on the back of a cabinet will make more sense even if not totally "right".
Midway between top and bottom units looks about right. There are no hard and fast rules. You can also use 45 degree sockets mounted at the top or the bottom of the gap if you prefer.
Again it is not specified in the regs, but you need to use common sense. Guidelines usually say 600mm is plenty, 300mm may be ok in many cases.
As above - no hard and fast rules, but you don't want to either melt the socket, or have a trailing lead draped over the hob.
If you follow the required zones (inline with accessories horizontally or vertically, and within 150mm of a corner or ceiling) then you can bury the cables directly. Since you are back to bare walls you may find plastic capping over the wires is simplest and that will give them protection when they are being plastered.
It is very hard to offer mechanical protection to wires anyway - especially against a determined numpty with a power drill or a masonry nail. Using RCD protection for all applicable circuits (i.e. not fridge/freezer/boiler) is usually far more effective.
The main loads are:
(1) Dishwasher 3kW perhaps - thermostatic control - shortish term (3) Under the counter single oven 2kW thermostatic control (4) Kick space heater (planned to be a fan and a radiator of the CH but a 2Kw all electrical jobbie may turn out cheaper). Not when you include the cost of running it! Having said that many kitchens require little or no heating much of the time. (1) Microwave (combination grill/microwave/oven) 2kW perhaps
So we are heading toward 9kW peak load, but with diversity and the thermostatic control that should be ok on a single circuit.
(5) Power to the gas hob for the ignition circuit. (2) Kettle 3kW - but very short term (3) Bread Maker 600W (4) Digital phone handset 10W (5) Hand blender (6) Towcester - could be 2kW - but short term (7) Possibly another toy or two if the mood takes us.
If you have the electric kickspace heater then you may want to put that on its own radial.
(2) Under the counter fridge 400W
Stick that on a non RCD radial - could be the same one as the heater.
There is a recommendation in the IEE Electrician's Guide to the Building Regulations (EGBR) that the horizontal centre line of such sockets should be at least 150 mm above the worktop, and that other sockets should be at least 450 mm above floor level. (IMO the latter measurement should be to the bottom of the sockets, to align with the Part M building regs requirements.)
The EGBR says 300 mm min., and so does NICEIC guidance. 600 mm is probably being over-cautious.
Given that the 17th edition regs are likely to be in force in less than a year and will require all sockets "intended for general use" to be RCD protected I'd be inclined to put everything on a single 30 mA RCD-protected ring circuit. Ideally a 32 A / 30 mA RCBO would be used as the protective device. A possible exception is the heater if that does end up as an electric heater rather than a fan-coil unit and is likely to be used for long periods, in which case a separate 16 A radial heater circuit may be justified on loading grounds.
To comply with the draft 17th ed. requirements any sockets which are _not_ 30 mA RCD-protected should be specifically labelled ("or otherwise suitably identified") and must be "provided for connection of a particular item of equipment" [Reg. 411.3.3 in the draft 17th ed.]
I would assume the positioning of a socket at the back of a 600mm wide gap under a worktop with connections for water and drainage etc, would be a fairly good example of "provided for connection of a particular item of equipment" - even without a label for the hard of thinking ;-)
(You can see it now: "How the heck do they expect I am going be able to plug the kettle in with that poxy washing machine in the way?")
You could argue that the positioning alone constitutes suitable identification, but then there's a counter argument that if no WM or DW is fitted in said gap the socket becomes available for general use, so perhaps a specific label is best, at least from an electrician's-arse-covering POV, if there's no RCD. Doubtless suitable ready-made labels will become available.
More than likely. I must admit that I do tend to print my own labels and stick them on anything non obvious like this[1]. I also like to label the above counter switches so that you know which appliance they isolate.
[1] I find a Brother laminated label maker very good for this, you can get a wide range of colours and styles of tape, and the labels are very resilient once stuck.
There is another option, which is to use a latching (or passive) RCD. It breaks the circuit on detecting a fault current, but on power fail (rather than detected fault), will automatically re-make the circuit when power is reapplied.
If you use two kitchen circuits, then the above-counter sockets can be on a non-latching (active) RCD, and the below- counter circuits for major appliances (including freezers) on latching (passive) RCDs.
This is just your normal paranoia about nuisance tripping which in practice is simply not a problem if the fixed installation and appliances are in good order. There are certainly good arguments though for using multiple RCDs or individual RCBOs to give improved fault discrimination, and it's to be hoped that the 17th edition will lead to the wider use of RCBO (combined MCB and RCCB) devices.
What are you on about? All DIN-rail RCDs for fixed installation use in consumer units and dis-boards are of that type (TTBOMK). By "active RCD" I presume you mean the type with a built-in no-volt release, as found in plug-in RCD adaptors and some 'RCD spur' units. Obviously that type would not be suitable except in special cases like workshops and lab benches where manual reset after a power failure would be preferable.
Thanks Andy. A good illustration of "if you want to get the right answer on Usenet, post the wrong one and wait for corrections".
The above was not intentional.
I wasn't aware that "all DIN-rail RCDs for fixed installation use in consumer units and dis-boards are of that type" i.e. passive, or latching - so I've learned something. Plug in RCD adapters come in both varieties (which I found out by fortuitous accident), and this is often not made clear.
It strikes me that there is very little downside to RCD protecting large appliances (even if double insulated) if DIN rail RCDs are latching. But perhaps I'm equally wrong in that statement.
On Mon, 30 Jul 2007 03:21:37 -0700, snipped-for-privacy@mail.com mused:
Depends on what large appliances you are referring to. A washing machine left unattended for a couple of days after an RCD has tripped without being noticed isn't a major hassle but a fridge\freezer would be a bit of a pain.
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