Kitchen rewiring- advice on new regs please

[Mike-W]

Hi all, particularly sparkie’s

I am working on a plan to enlarge our kitchen in our Bungalow by demolishing the dividing wall between our current kitchen and bathroom (and moving our bathroom into the garage).
I have three electrical questions I’m hoping someone can help me with:
Naturally if I enlarge the kitchen I will need to extend the ring main into the area that is currently the bathroom.
1. With the requirement for harmonised colours wiring now law I am not sure about extending the ring from existing wiring, can I use the existing red/black cables and connect the new cable as brown / blue where I need new sockets or do I need to install a completely new circuit from the consumer unit?
2. I know this insulation will be covered by part ‘P’ building control, I am fairly confident about doing the electrical work myself and I would like to get the latest IEE 16th edition wiring regs, my copy is well out of date (1994). The 2004 pocket edition is £46.55 from Amazon! Can anyone familiar with the latest wiring regulations suggest a good up-to date book covering wiring design/regulations in the home?
3. I am thinking about replacing my consumer unit anyway from a wire fused type to a Wylex MCB with a RCB trip, the consumer unit offered by Screwfix is described as a 12 way flexible split load consumer unit, any ideas what the split load is about?

Any suggestions would be helpful as I have lots of ideas bouncing around in my head at the moment!

Mike.

 

[PowerTool]

Hi Mike - I'm an enthusiastic DIY-er,and NOT a pro,but here's a couple of thoughts

1. With the requirement for harmonised colours wiring now law I am not sure about extending the ring from existing wiring, can I use the existing red/black cables and connect the new cable as brown / blue where I need new sockets or do I need to install a completely new circuit from the consumer unit?

Believe you can connect new to existing (as it is an existing circuit) but need to label the consumer unit to say that both "old" and "new" coloured wiring can be found.

2. I know this insulation will be covered by part ‘P’ building control, I am fairly confident about doing the electrical work myself and I would like to get the latest IEE 16th edition wiring regs, my copy is well out of date (1994). The 2004 pocket edition is £46.55 from Amazon! Can anyone familiar with the latest wiring regulations suggest a good up-to date book covering wiring design/regulations in the home?

Sorry,don't know (although the craftsmans book club http://www.readersunion.co.uk has several)

3. I am thinking about replacing my consumer unit anyway from a wire fused type to a Wylex MCB with a RCB trip, the consumer unit offered by Screwfix is described as a 12 way flexible split load consumer unit, any ideas what the split load is about?

Split-load - not all of the circuits are protected by the RCD (Residual current device) ; there are different trains of thought on what should and should not be protected - sockets generally should be,but you might want the freezer on a seperate circuit that isn't.If any circuit on the RCD side develops a fault,ALL the circuits covered by it go off.

Hope this helps,but as always,if in doubt,consult a qualified electrician.

Andrew

 

[Mike-W]

Thanks Andrew,

I have been doing a bit more research on the web after I posted the question, and yes much of what you said is in agreement is what I have found on the web.
On the question of harmonised colours I may have been confused by some old information which I think said ‘old and new colours could not be mixed on the same circuit. I think that information may have been re-written.
I'm still considering replacing the consumer unit from a wire link type, particularly in view of the fact I don’t need to wire all the circuits through the RCD.


Mike

 

[davy_owen_88]

If you are mixing wiring colours through the whole installation you need a cable colour warning sticker on the CU. If you are mixing wiring colours within a circuit, it's a good idea to sleeve the new colours with the old as well.

The Guide to the IEE Wiring regulations is a very handy book and gives all the info you are likely to need in a simple fashion. As a DIY'er who will be notifying the work and getting it inspected+tested by someone else, you are not required to have a copy of BS7671 and as such I wouldn't waste your money on one. You can get all the info you need over at the DIYnot forum where I spend a fair bit of time and you will usually get a good answer very quickly. On the other hand I'm more than happy to answer any other questions if you want to email/PM me.

A modern consumer unit with integrated RCD is the norm nowadays. A better solution - although somewhat more expensive is to use RCBO's - these are a combination of an MCB and an RCD in a single 'way' and this helps to prevent nuisance tripping because only the one circuit is effected when the RCD part 'trips'. It also nearly removes the issue with small amounts of earth leakage building up in several circuits.

It is highly recommended that you RCD protect all socket circuits, but the only one that is required by BS7671 is those that are likely to supply portable equipment outside the equipotential zone (i.e outside your house).

Certain appliances within the bathroom require RCD protection also, although showers do not require RCD protection, it is almost always a manufacturers requirement and as such overrules BS7671.

Before you go buying a consumer unit though, it is vital that you know what earthing arrangement is available to you. A TT supply (one that requires an earth electrode) will need two RCD's. A 100mA time-delayed RCD that protects the entire installation and a second 30mA RCD for certain circuits. If you have a TT supply and are carrying out electrical work, it is usually the same or cheaper to have a PME earth installed than to pay for a TD RCD.

Another thing to consider is that earthing and main bonding must be brought up to date when you carry out electrical work, and your BCO inspector will insist on this. The standard for domestic properties is 16mm² main earth and 10mm² main equipotential bonding to all metal services (gas, water etc.)

 

[OLD]

I had this on file it may help:-
http://www.stapeley1.plus.com/odpm_breg_029960 elec regs.pdf

 

[Mike-W]

I absolutely agree Old - yes it is all about communication, I have had excellent help from three members and the advice has been spot on, it’s certainly enabled me to develop my ideas into an achievable plan. That’s what I particularly like about this forum you can ask almost any question and someone will have an answer!

Davy;
a couple of issues you mentioned were particularly helpful, I will be looking at using RCBO’s in my consumer unit, when my wire fuse consumer unit was installed twenty years ago RCBO’s were not available and I did not want all power tripping if a fault occurred on one circuit. I currently have only one (outside) circuit covered by a RCD for exactly the reason you mentioned of multiple circuits shutting down when the ‘master’ RCD trips.
I have checked my incoming Earth, there is a label marking it as a Protective Multiple Earthed System (my bungalow was built 30 years ago on an estate, I guess it was normal then not to rely on grounding through the water supply pipes or earth spike?)
The bonding issue was something I had overlooked, certainly I will check my Utility room as I plan to re-plaster and rebuild that before I start my Kitchen and I cannot recall seeing any bonding on the plumbing in that room.
Andrew mentioned putting the freezer on a circuit not covered by a RCD, is it acceptable to put 13 amp sockets on a radial installation where only a few outlets are required to cover such devices?
Mike

 

[davy_owen_88]

The biggest problem with answering your question is that your BCO inspector has the authority to enforce his own view of the regulations and there is very little you can do about it, even if he is incorrect. As such, I would hate to say that you can do something only for the inspector to label it unsafe.

Whilst it is within regulations to have socket outlets that are not RCD protected feeding appliances that are not going to be used outdoors, you have to prove that the socket is not 'reasonably expected to supply' any outdoor equipment. The socket being behind a fridge isn't always going to be enough for a jobsworth inspector.

One solution is to connect your fixed kitchen appliances (fridge, freezer, washing machine, dishwasher etc) using a dedicated 4mm² radial and a grid switch. For each appliance you need 1x 20A DP switch + 1x fuse unit and from there you can feed flex outlet plates for you to hardwire your appliances into. One The disadvantages of this is that by removing the moulded plugs you may void the appliances warranty and certain appliance engineers will not work on appliances that they can not physically 'unplug'. The benefits are no visible cables, a neat control panel for all your appliances and a great reduction in the possibility of nuisance tripping because the majority of the 'leaky' appliances are connected to the non-RCD side.

You will of course need a dedicated, RCD protected circuit feeding the kitchens socket outlets.

 

[sparrow]

I replaced my old fusebox a couple of years ago with a splt load CU. It was straightforward. I installed a 9.5 kw shower at the same time. The shower manufacturer insisted that went through the RCD, and to be frank I'd not want to stand under an electrical item in my bathroom that was pouring water over me that was not RCD protected.

My mate, an electrican, advised that any downstairs socket could be likely to supply an outside connection and so than meant both 20A socket rings had to go through the RCD. My ring mains do half upstairs and half downstairs each. A simpler arrangement would be to have up and down on separate circuits.

All this meant I needed to discard the 60 Amp RCD that came from Screfix with the CU (I used an MK one) and buy an 80Amp one. The main supply breaker is 100 Amps.

My freezer is throught he RCD - no tripping as yet in two years. I was going to run a separate circuit for the freezer using one of the spare ways in the CU, but have not found it necessary.

Now I am about to move to an old cottage that has had it's wiring done but has no RCD. It has mini-circuit breakers in a reasonably modern CU, so I might just use RCBOs on the ring mains and leave it at that - if they will fit in.