UK electrical wiring - Page 1
Forum section: electronics / general

author: Majorbob
author_rank: Regular Contributor
timestamp: February 13, 2021, 05:21:19 am
content: I'm looking at rewiring my house because it's awful and there aren't enough sockets where they need to be. I've been brushing up on my knowledge of the IET regs and am wondering why the bottom of walls is not a "safe zone" (to use 17th ed terminology). I like the idea of having the wiring going through the skirting as I have heated flooring and, to me, it seems a much more logical place to route it all for increased adaptability and ease of access in the event of faults or additions than burying it in the wall. (For reference all walls are brick, including internal.)My question is why is this deemed such a bad idea? I've seen people saying about people banging nails etc into the skirting but I can think of 0 (zero) times I've seem something nailed or screwed there! (Except cable clips).

author: james_s
author_rank: Super Contributor
timestamp: February 13, 2021, 05:28:25 am
content: That would certainly be illegal here for exactly the reason you state, but then so would burying wires under the surface of a wall where someone could put a nail in to hang a picture or install a shelf or something. Either way if the convention is to not have any wires in certain places then people getting into those areas in the future are not going to expect there to be wires in the way. There also may be some consideration for flooding, especially if you have any junctions down low.Bottom line is it doesn't really matter why the code requires what it does, you have to follow the code anyway.

author: Monkeh
author_rank: Super Contributor
timestamp: February 13, 2021, 05:32:01 am
content: Quote from: Majorbob on February 13, 2021, 05:21:19 amErr, because the cables would be behind the skirting you're likely to fix with nails or screws.You can use trunking as skirting, at which point it's no longer buried and safe zones don't apply, but you probably won't like the PVC aesthetic..Quote from: james_s on February 13, 2021, 05:28:25 amThat's.. where all your cables go as it is.

author: gnuarm
author_rank: Super Contributor
timestamp: February 13, 2021, 05:46:50 am
content: Quote from: Monkeh on February 13, 2021, 05:32:01 amI'm with the OP on this one. I'm in the US so I don't know how homes are built in the UK, but here we use wooden studs for framing and drywall (also known as sheet rock) for the wall itself. Wiring is run through holes drilled in the studs and electrical boxes secured to the sheet rock or to the studs. There are no regulations on the height of the wiring that I am aware of. I know vertical wires are to be affixed to a stud but the horizontal wiring is simply run though the holes in the studs.So most wiring is at the level of outlets which are about two feet off the ground (the height of the outlet boxes is standard), or up and down the studs. Working on walls people know this and avoid those areas. I believe a metal plate is supposed to be used behind the sheet rock where a wire goes through a stud because nails are commonly driven there. Drive a nail into sheet rock and it will just fallout again.So why would anyone be putting nails randomly through panels knowing wiring might be on the other side? Don't you use studs? Or is the paneling heavy enough that screws and nails are driven through them?QuoteYeah, I'm not picturing this at all.

author: Monkeh
author_rank: Super Contributor
timestamp: February 13, 2021, 05:55:20 am
content: Quote from: gnuarm on February 13, 2021, 05:46:50 am

author: Majorbob
author_rank: Regular Contributor
timestamp: February 13, 2021, 06:02:11 am
content: Quote from: Monkeh on February 13, 2021, 05:32:01 amBut surely if you are fixing the skirting with nails or screws then you should be aware that the wiring is there?For a reference to all of you who are outside of the UK this is a picture showing the "permitted wiring zones".

author: Monkeh
author_rank: Super Contributor
timestamp: February 13, 2021, 06:04:23 am
content: Quote from: Majorbob on February 13, 2021, 06:02:11 amNot if it's been covered over to provide a surface you can fix the skirting to?

author: Majorbob
author_rank: Regular Contributor
timestamp: February 13, 2021, 06:11:27 am
content: Sorry, I don't grasp that, not if what has been covered over?The skirting will be recessed at the back to allow wires to travel safely between it and the wall, and vertical holes will be made where required to feed sockets mounted directly above the skirting.

author: Monkeh
author_rank: Super Contributor
timestamp: February 13, 2021, 06:14:47 am
content: Quote from: Majorbob on February 13, 2021, 06:11:27 amWell that's ugly. You're looking for the council estate appearance then?You underestimate the space required by the wiring compared to the area you could remove from the back of a piece of skirting. Now imagine someone coming along wanting to fit a doorstop..

author: Majorbob
author_rank: Regular Contributor
timestamp: February 13, 2021, 06:26:23 am
content: Quote from: Monkeh on February 13, 2021, 06:14:47 amAesthetics will come later when I've determined the viability. My goal at this stage is to gain an understanding of why it seems such an unpopular idea and whether it's worth continuing with.Deep skirting with enough material to make space for T&E is available, and skirting can easily be high enough to have seperate channels for data/power/TV etc. Doorstops had escaped my mind, it may be end-of-nightshift-brain not working properly but there aren't many things that would be normally attached to the skirting?

author: Monkeh
author_rank: Super Contributor
timestamp: February 13, 2021, 06:33:00 am
content: Quote from: Majorbob on February 13, 2021, 06:26:23 amSpecifically burying it in the wallbehindskirting is not acceptable for the reason I gave. Putting it in the skirting is unpopular because it's ugly.QuoteProducts are specifically available for this purpose. They're ugly, and if you paint them the paint is destroyed when opening. If you fill and paint modified wooden skirting, the skirting is destroyed in gaining access. I suppose real wood with brass screws could look okay and be removable, but the damage then done to modify wiring behind it defeats the idea. Running up on the surface is impractical with multiple compartments.This stuff may survive the removal of the cover with care:https://www.rockwellbuildingplastics.co.uk/products/mdf-skirting-trunking-65mm-x-24m-white.htmlSurface runs out of that would be gopping. It's just barely big enough for some T&E.

author: Majorbob
author_rank: Regular Contributor
timestamp: February 13, 2021, 06:42:50 am
content: Quote from: Monkeh on February 13, 2021, 06:33:00 amI understand the burying it in the wall point, plus if you're going to bury it in the wall, you might as well do it at the same level as your sockets.QuoteYes, I have seen the kind of ugly PVC skirtings with multiple compartments. I have also seen skirting with routed channels, but you make a good point with its removal.You make some good reasons against the idea and have given me good thinking food, thankyou.

author: Majorbob
author_rank: Regular Contributor
timestamp: February 13, 2021, 06:45:21 am
content: QuoteI've seen the rockwell stuff before and decided it'll be too ugly/too much hassle. You'll get T&E along it but you'll struggle getting it round a bend or out again!

author: james_s
author_rank: Super Contributor
timestamp: February 13, 2021, 07:28:34 am
content: Quote from: Majorbob on February 13, 2021, 06:02:11 amWhat about the next person who lives in the house? Most houses go through multiple owners, and many people will expect things to be done according to code. Again, if the electrical code forbids running the wires where you want to run them, it doesn't matter why it's forbidden beyond curiosity, you can't do it in a way that is not compliant to code. If you are doing something as major as rewiring the house I would hope that you're going to get it properly permitted and inspected. This is a much more major undertaking than adding a socket or a light somewhere.

author: gnuarm
author_rank: Super Contributor
timestamp: February 13, 2021, 05:02:55 pm
content: Quote from: Majorbob on February 13, 2021, 06:11:27 am"English is the common language that divides our countries."I think my idea of skirting is not like yours. Perhaps you can explain what that is.In the US wires are either behind the drywall or are in a metal conduit or raceway on the surface. Wires are not run within layers of drywall (sheet rock) or paneling (looks like wood but rather thin).

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 13, 2021, 05:09:21 pm
content: Quote from: Majorbob on February 13, 2021, 06:45:21 amIf it's in trunking you could surely use singles instead of T&E ?

author: Monkeh
author_rank: Super Contributor
timestamp: February 13, 2021, 05:11:14 pm
content: Quote from: mikeselectricstuff on February 13, 2021, 05:09:21 pmThe entire run including any penetrations through walls and runs in floor and ceiling voids would then have to be in conduit or trunking, unless you add lots of joints and enclosures for them..

author: themadhippy
author_rank: Super Contributor
timestamp: February 13, 2021, 05:20:18 pm
content: yes you can run the wiring behind the skirting.as long as its in metal conduit, steal wire armored cableor some other earthed metallic covering.I do hope you've registered the job with your local council buildings control office and paid the appropriate fees.

author: nctnico
author_rank: Super Contributor
timestamp: February 13, 2021, 05:24:18 pm
content: Quote from: Majorbob on February 13, 2021, 05:21:19 amIf the walls are brick then I'd cut slits in them to facilitate extra wiring (in conduit -but don't use the flexible stuff; pulling wires through it is horrible-). You can rent machines to cut these slits. Building some kind of trunking onto the walls is beyond ugly.

author: gnuarm
author_rank: Super Contributor
timestamp: February 13, 2021, 05:32:03 pm
content: Quote from: nctnico on February 13, 2021, 05:24:18 pmBrick!!! Don't you guys add insulation at the inside face of the brick? No framing? No space to add insulation? That is where wires are run in the US.I recall a home improvements TV show at a construction site where they used site fabricated, solid foam insulation for walls. They had to cut openings for doors and windows. They indicated running wiring was a bit of a bother, I don't recall how they managed that. I've never heard of this becoming popular.

author: themadhippy
author_rank: Super Contributor
timestamp: February 13, 2021, 05:51:48 pm
content: QuoteAll depends on the way its built,but generally internal walls wont be insulated.To run the wires on brik walls there placed nice and flat against the wall and covered in either capping (plastic or metal) or oval plastic conduit.The wall gets plastered burying the cables,the covering is to stop the mud chucker (plasterer) from damaging the cables.Nowadays most new homes use stud work for internal walls so the wiring will in the gap between the boards.

author: Zero999
author_rank: Super Contributor
timestamp: February 13, 2021, 09:32:01 pm
content: Quote from: gnuarm on February 13, 2021, 05:32:03 pmYes brick. Insulation is in a cavity between two brick walls.

author: iainwhite
author_rank: Unknown
timestamp: February 13, 2021, 11:12:02 pm
content: It is often an inner wall of concrete blocks and an outer wall of brick, separated by an air gap containing insulation.

author: james_s
author_rank: Super Contributor
timestamp: February 14, 2021, 12:36:06 am
content: You certainly wouldn't see anything like that out here in earthquake territory. Looks like it would pose a far greater resistance to fire than the wood houses we have though. Seems like a really easy way to wire a home like that would be to run conduit from box to box and plaster over that.

author: Monkeh
author_rank: Super Contributor
timestamp: February 14, 2021, 12:39:02 am
content: That is essentially what happens, yes. And why we have safe zones (which extend to most stud walls as well), because thick, heavy, expensive metal conduit isn't really worthwhile.

author: IanB
author_rank: Super Contributor
timestamp: February 14, 2021, 12:55:31 am
content: Quote from: james_s on February 14, 2021, 12:36:06 amTraditional homes in Britain were built as shown above with brick outer walls and "breeze block" inner walls and dividing walls. It gives the whole house a much more solid feel with better soundproofing. Newer homes are generally timber framed with brick outer facing to protect against the elements but wooden studded inner walls with plasterboard, because it is faster and cheaper to construct that way. However, if you build your own home and pay the builder to do it how you want it you can readily have an all-brick house.I am rather curious about the best way to rewire a 1960's brick home, since cutting channels in the wall to bury the new cable seems to be too expensive/too much trouble for contractors to contemplate. Now if they had built the house in the first place with buried conduit, it would just be a matter of pulling new cable through in place of the old...BTW, not many people have died from earthquakes in the UK. I think there has been maybe one casualty in the last few hundred years when a roof tile landed on his head.

author: Monkeh
author_rank: Super Contributor
timestamp: February 14, 2021, 12:59:29 am
content: Quote from: IanB on February 14, 2021, 12:55:31 amBeing that it's the normal method of construction here, it's quite normal to deal with chasing out the plaster and a little brick if needed. The other option is surface trunking, which is cheap, fast, and ugly, and how pretty much every council home will have been done.

author: james_s
author_rank: Super Contributor
timestamp: February 14, 2021, 01:09:20 am
content: Quote from: IanB on February 14, 2021, 12:55:31 amI've never heard of an earthquake in the UK, I haven't looked it up but I don't think it's very common at all there. Here on the West coast of the US they are a frequent occurrence though. Most are not of sufficient magnitude to be felt but every few years there's a small but noticeable tremor and usually every 30 years or so there's one large enough to cause some damage so it's a concern here. If not for that then brick and concrete would be very appealing for the reasons you mention.Cutting channels in plaster could be accomplished in a few minutes with an appropriately configured router and filling them in would be no harder than patching the holes that are necessary for fishing new wires through existing studded walls. That sort of thing is never permissible here for line voltage wiring but I've done it a few times for low voltage network cables as there are much less stringent requirements for low voltage. Proper conduit is fantastic and a dream to work with but rarely seen in domestic environments except in garages and unfinished basements some jurisdictions require conduit for those areas where the wiring is otherwise exposed. If I were wiring a whole house from scratch though I'd be really tempted to do the whole thing with rigid galvanized conduit and the big spacious metal boxes with mud rings like they use in commercial buildings. My mother's house was owned by a commercial electrician and he wired the additions that way and it has been a real pleasure to work on compared to what I'm used to.

author: iainwhite
author_rank: Unknown
timestamp: February 14, 2021, 01:10:36 am
content: Quote from: gnuarm on February 13, 2021, 05:02:55 pmSkirting = Baseboard

author: Monkeh
author_rank: Super Contributor
timestamp: February 14, 2021, 01:14:40 am
content: Quote from: james_s on February 14, 2021, 01:09:20 amThere have been 25 recorded in the last 50 days. At least four of them felt. None sufficient to bother anything built properly.

author: nctnico
author_rank: Super Contributor
timestamp: February 14, 2021, 01:39:11 am
content: Quote from: gnuarm on February 13, 2021, 05:32:03 pmOver here it depends a bit on the build style but typically there is an outer layer (can be brick, wood, whatever), and insulation layer and inner walls (can be concrete or brick). Wiring conduit is integrated in the walls. From what I've seen from British home improvement shows they don't build home much differently.In the US the building style is completely different though.

author: gnuarm
author_rank: Super Contributor
timestamp: February 14, 2021, 01:43:16 am
content: Quote from: iainwhite on February 14, 2021, 01:10:36 amOk, in the US I don't know if it is prohibited, but we pretty much never run wiring in the base board (we do have baseboard heating elements though). I think in the UK there are a lot more older buildings that need to be accommodated. Here there's not much that wasn't built with studs even if it uses something other than dry wall for the surface.We just don't seem to have problems with this.Oh, I very seldom see anything inside a brick wall other than stud construction. I have seen a few colonial era homes with the same brick inside that is outside. Brrrr... no insulation at all. That was a long time ago and I don't know how the ran wires. Probably just avoided that wall.

author: james_s
author_rank: Super Contributor
timestamp: February 14, 2021, 02:50:26 am
content: Surface raceways are relatively common here in some situations, I think they were especially popular in the 70s. They're a sort of conduit that consists of a backing plate that is screwed to the wall and then a rectangular cover that snaps on over it. It was used a lot for retrofit work, especially in commercial situations but I've seen it in homes too, especially in this situation where there's no stud space to run the wire through. Our cabin has some of the wiring done in raceways that are run along the exposed wooden beams.

author: themadhippy
author_rank: Super Contributor
timestamp: February 14, 2021, 03:03:37 am
content: QuoteIf your lucky 60's era house has metal oval conduit buried in the wall that you can pull your new cables into,using the old cables as a draw wire,so avoiding any chasing,even if there blocked they make chasing the wall out easier as its only plaster you need to removeQuoteyes theres proper chasing tools,bit like a circular saw with 2 blades,but they are very messy and need some form of vacuum attached unless you want to be cleaning up forhoursdays,however the easiest option is to give the apprentice a lump hammer and bolster chisel and tell em to get on with it,once you get the knack you can chop a box and chase out pretty quick,unless its engineering brick.

author: IanB
author_rank: Super Contributor
timestamp: February 14, 2021, 03:37:52 am
content: Quote from: Monkeh on February 14, 2021, 12:59:29 amI think the plaster isn't deep enough, it's only a skim on the surface of the bricks. Surely to cut deep enough to bury wiring you need to chisel out the mortar between the bricks? I remember when my father was installing spurs he spent quite some time with a hammer and chisel doing that. And the original wiring was installed the same way. Obviously cutting out holes for the boxes involves even more chiseling. The apprentices when they were building houses in previous decades must have had plenty of work to do.

author: Monkeh
author_rank: Super Contributor
timestamp: February 14, 2021, 04:01:31 am
content: Quote from: IanB on February 14, 2021, 03:37:52 amIt's a lot thicker than you think it is. The base coat is usually up to half an inch thick.

author: nfmax
author_rank: Super Contributor
timestamp: February 14, 2021, 08:50:01 am
content: Quote from: Monkeh on February 14, 2021, 01:14:40 amIt's been almost 90 years since the last majorearthquake(Richter magnitude > 6) in the UK. The epicentre being out at sea, damage was limited. However, the Dogger Bank is now a major centre of offshore windfarm development.

author: nctnico
author_rank: Super Contributor
timestamp: February 14, 2021, 04:53:30 pm
content: Quote from: IanB on February 14, 2021, 03:37:52 amNowadays you use a mill (*) for the conduit and round drill for the junction boxes. Don't chissel out the mortar; that is too narrow for the conduit to fit into anyway.* something like this:or this:

author: coppice
author_rank: Super Contributor
timestamp: February 14, 2021, 05:03:22 pm
content: Quote from: IanB on February 14, 2021, 12:55:31 amNo it wouldn't. By the time the place needs rewiring usage patterns have changed, new bits and pieces altered from the original layout of the wiring, and the amount you can simply pull through the original conduits is limited. Conduit always sounds so flexible, but seldom really works out.

author: IanB
author_rank: Super Contributor
timestamp: February 14, 2021, 05:35:23 pm
content: Quote from: coppice on February 14, 2021, 05:03:22 pmFor instance, I grew up in a house that was built around 1960, and the builders only included one socket in each bedroom. I'm not sure how they ever thought that would be enough.

author: coppice
author_rank: Super Contributor
timestamp: February 14, 2021, 05:44:53 pm
content: Quote from: IanB on February 14, 2021, 05:35:23 pmThat was normal in 1960, and was considered perfectly adequate. By the mid 70s it was looking a bit weak, although even then if you suggested putting in lots of sockets many people complained that they didn't want their walls covered in sockets. The real problem with the one socket tended to be that they put it in the least useful spot in the room.

author: james_s
author_rank: Super Contributor
timestamp: February 14, 2021, 06:46:47 pm
content: Quote from: IanB on February 14, 2021, 05:35:23 pmMy aunt & uncle live in a house built in 1922 and originally when built there was only one duplex receptacle in many of the rooms, I think two in a couple of the larger rooms and this is a fancy enough place to have what was originally a maid's quarters in the basement. More were added sometime in the 1950s judging by the wire used, and then they added more in the 80s and 90s. Used to be people didn't have much that needed to be plugged in. A family might have a radio, a vacuum cleaner, a clothes iron, maybe a few lamps. For whatever reason ceiling lights went out of fashion in 1950s-60s America and lamps became very popular and people also started owning a lot more electrical gadgets in the post-WWII boom years.I find there are never enough receptacles even in modern houses and there is never one quite where you need one. I would love to have them every 4' on every wall in the house, and a double gang box with a pair of duplex receptacles is preferable to a single one just about anywhere, you can never have too many places to plug something in. At this point I have 6-way adapters and power strips all over the house, the total load is not high but there are a lot of things plugged in.

author: Cerebus
author_rank: Super Contributor
timestamp: February 15, 2021, 03:21:21 am
content: Quote from: james_s on February 14, 2021, 12:36:06 amThat's exactly what is done for a plastered brick wall, except it's not conduitper se. You chase out a channel with one of these:Then you put "twin and earth":aka '6242Y' into the channel, cover it with PVC capping:nailing the edges into the wall, and finally plaster over the top.The OP ought to acquaint himself with the Building Regulations part 'P' before embarking on any DIY re-wiring and should be aware that most work of any significance will have to be inspected by either a 'registered competent person' or a building control officer.A note for the non-brits reading this: There is not a statutory code for electrical wiring in the UK in the same sense there is in other places. There is the IET wiringregulations, which are misleadingly named, they arenotgovernment regulations, merely guidelines issued by the IET. The actual government regulations are quite short and sweet, and basically boil down to electrical installations must be safe and not present a risk of fire or electrical shock. Following the IETguidelinesis generally regarded by the various bits of government as an indication that the real regulations have been met, but it does not, and never has, definitively indicated that an installation meets the statutory standards - it is quite possible to 'do it the way the book says' and produce an unsafe installation in some circumstances. An indication of this is the boilerplate wording from the Health and Safety Executive that you'll find prefixing every issue of the IET Wiring 'Regulations' in recent years, vis:Quote from: Note by the Health and Safety Executive

author: Majorbob
author_rank: Regular Contributor
timestamp: February 16, 2021, 09:28:52 pm
content: In this greatly informative discussion I have started looking into Part P, I spend every day modifying wiring in machines where "along that random bit of framework is fine, just cable tie a bit of conduit until you have time to fix it properly" is an unfortunately common occurrence (and often takes a long time until it is fixed properly). I have had some exposure to the 17th (and 18th) editions but the course is for the facilities team, which isn't me.I have now given up on the idea of running behind skirtings, as laying metal conduit or running SWA just isn't really going to be feasible... especially once it's run up to sockets... I don't need my house looking like a machine cell at work!Thankyou all for good discussion and aiding my understanding, planning for the rewire can now continue!