17th Edition. Where do all the bits go?


Postby Eastworth » Fri Mar 02, 2012 11:22 am

I rewired my own house about 10 years ago. I've now bought a restoration project. I understand that 17th edition and Part P have changed things from the last time I did this, but still want to do a lot of the donkey work myself. I certainly want to lay in the cable and fit the wall boxes to save a lot of the cost.

1 - All the wiring is going to be routed from the first floor void. So for sockets and switches most mains cables will need to be chased into the walls. I have read somewhere that when chasing in, I need to use metal chanelling that has to be earthed to something. Is that right? and to what is it earthed to? I have a fully plastic piping system in the house.

2 - In terms of ring main wiring, is it best to wire in and out of a socket every time, or can I use junction boxes and wire sockets with a single cable?

3 - Some areas will have more than one socket side-by-side. Can I drop a vertical cable into the first, run horizontally to the second and third and then return through the boxes and back up the same channel as the drop? Or do I need a separate drop per socket?

4 - I understand the minumum heights for sockets (450mm) from the floor but what about ones above kitchen units and built-in cupboards. Do they need to be a minimum hight about the surface?

5 - Similarly light switches. They seem to be at virtually waist height in new houses! (they do when you're 6'2") What's the minimum and maximum heights now allowed?

5 - Is there a quick reference guide to 17th edition I can access? Again, I've read on here that the LABC people can get pedantic on the number of cable clips you use.

Thanks in anticipation for your help.
Eastworth
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Postby ericmark » Fri Mar 02, 2012 10:43 pm

[quote]I certainly want to lay in the cable and fit the wall boxes to save a lot of the cost.[/quote]Not sure if it will save that much because of LABC charges[quote]

1 - All the wiring is going to be routed from the first floor void. So for sockets and switches most mains cables will need to be chased into the walls. I have read somewhere that when chasing in, I need to use metal chanelling that has to be earthed to something. Is that right? and to what is it earthed to? I have a fully plastic piping system in the house.
[/quote]With RCD protection on all circuits no you do not need any capping although often plastic capping is used to protect wiring from plasters trowel.[quote]

2 - In terms of ring main wiring, is it best to wire in and out of a socket every time, or can I use junction boxes and wire sockets with a single cable?

[/quote]The question radial or ring is quite complex no easy answer as to best method. Junction boxes need to be either special type of accessible so would not normally use them in a rewire.[quote]

3 - Some areas will have more than one socket side-by-side. Can I drop a vertical cable into the first, run horizontally to the second and third and then return through the boxes and back up the same channel as the drop? Or do I need a separate drop per socket?

[/quote]Yes you can run cables vertical or horizontal.[quote]

4 - I understand the minumum heights for sockets (450mm) from the floor but what about ones above kitchen units and built-in cupboards. Do they need to be a minimum hight about the surface?

[/quote]Part M I think from memory and for existing premises not normally a problem one can normally keep them to the same height as originals. There are some odd bits like 1200mm limit for manual operated item but also minimum for item to be visually read so where does one mount a thermostat will need to be spot on 1200mm however my mother in a wheel chair can't read that. So if you have a good reason why it should not be at the heights given then you can get away with other heights. Mounting so the bed will not damage the socket i.e. low as long as you state why is normally accepted.[quote]

5 - Similarly light switches. They seem to be at virtually waist height in new houses! (they do when you're 6'2") What's the minimum and maximum heights now allowed?

[/quote]As with sockets see above 450mm to 1200mm but again give good reason why they need to be at another height and likely there will be no problem.[quote]

5 - Is there a quick reference guide to 17th edition I can access? Again, I've read on here that the LABC people can get pedantic on the number of cable clips you use.

[/quote]There are guides to 17th Edition and it is the guide which says how many sockets a bedroom should have not the 17th Edition it's self. It is written to cover all and quite heavy reading. For example it does NOT say you need two RCD's but it does lay out rules which would be hard to comply with without using at least two RCD's.[quote]

Thanks in anticipation for your help.[/quote]

The Parts of the building regulations can be down loaded for free. Part P is main electrical one but Part J and M also have a bearing on what you can do. Extractor fans in bathrooms for example. They don't need to be connected to lights.

The big problem is inspection and testing. This has to be on going throughout the installation no one can come at the end and pass it all. There is provision for three signatures on the forms but in real terms if your doing the work you need to make out the paperwork. The LABC will then look at your readings and decide if they believe it and just issue the completion certificate or if they want to confirm the readings. So you can't really just guess at the reading. Also they have to decide if you have the ability and even I struggled to get them to accept I had the required skill with C&G 2381 (as it was then) and 2391. Only when they realised I also had a degree did they back down and allow me to go ahead.

We must face it before Part P we all both DIY and the professorial skipped on a lot of the work we should have done. Today one needs all the test gear before one can consider starting and at £75 to hire (week) and £750 to buy the cost to DIY is not cheap. Add to that the LABC charges and your looking at £1000 for test gear and charges.

Testing is not just plugging in and taking the reading you must know what passes. And also with the meter using 500v to test you do need to know what you are doing.

Although in theory you can DIY in practice it's really for people like me who are electricians but not a member of a scheme.
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Postby jimmy_one_ball » Sat Mar 03, 2012 9:54 pm

Helo

I can give you quick answers to those questions:
1. No you don't need metal conduit, just plastic capping or plastic oval conduit to protect the PVC from the heat given off when cement dries.
2. No you can't use junction boxes like that in a ring final circuit, both cables go to every socket outlet, unless you spur from a socket outlet (one unfused spur per socket outlet or unlimited fused spurs per socket outlet)
3. Yes you can do that but good practice is to alternate sockets outlets along the cable.
4. Current guidance suggests 150mmm from kitchen work surface to socket outlet.
5. Current guidance suggests 1200mm otherwise you may be discriminating against disabled people! Imagine two lines around the room, 450mm and 1200mm from finished floor level, put everything in there and you'll be fine (including the consumers unit).
6. You need the On Site Guide (green copy not red or brown) and the Electricians Guide to the Building Regulations (including Part P). Both on Amazon around £15 each. All guidance is in there and no the Buildings Inspector won't give a hoot about cable clips! As long as all the cables are adequately supported he'll be happy, he'll want the Electrical Installations Certificate though and the test and inspection results.

If you fancy a crash course on the testing and inspection then you'll need the Guidance Note 3
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Postby sparx » Sun Mar 04, 2012 10:56 am

Hi as you say regs have changed! Not withstanding all above comments the fact is that if you want to DIY the job then LABC MUST be informed before you start any such work and an inspection fee around £220 paid up front. They will then employ someone to inspect the wiring routes etc before making good.
They then have a second inspection at the end and want a copy of the Electrical Installation Certificate.
They then will hopefully issue a compliance cert.
The only other way is if you employ an electrician who can self certify the work via one of the scheme operators ie Elecsa, BSI, NAPIT, NICEIC. etc.
Are you really competant to change a consumer unit safely?
Best/cheapest way forward is to find a local registered leckie who may agree to you doing the 'donkey work' under his guidance to save labour costs, he will do all the main connecting, he then can register the work and issue certs. Bearing in mind he is taking responsability for the whole job.
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Postby Eastworth » Sun Mar 04, 2012 4:49 pm

Thanks to you all for your excellent advice. You've helped me to update my thinking a bit.

I'm tending towards the advice from Sparx i.e. do all the channelling and letting in of the boxes and the routing of the cable under the supervision of a leckie and get him to wire it up.

The consumer unit moving to a different place, so I could wire it up "off-line" and let the leckie hook it up to the tails when the meter has been moved.

It does seem daft to pay someone to cut holes in the walls and do the basics when I have the skills to do it myself.

One thought, though, we are having a load of other work done, including some structural things, so the LABC are already involved; do I need topay a separate inspection fee for the electrics, or is it all wrapped up with the overall inspection?
Eastworth
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Joined: Thu Mar 01, 2012 10:39 pm


Postby ericmark » Sun Mar 04, 2012 8:04 pm

LABC fees will cover what you asked for. If you declared that you are doing the electrics then it will cover. If not then likely it will not cover.

Reading other posts this has been a bone of contention where people expected the LABC were including the electrics but they had been vague in the application and the LABC did not know it was to be included.

The big thing is the rules as to charges was changed. So now it seems and it's still not clear that you should do inspection and testing and they only need to check items to ensure you have valid readings. However if the suspect that it's not done correct and they employ a contractor to test your work they can pass on the costs to you.

It also seems more changes are due and England and Wales will be getting different regulations.
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