Prescribed zones, chase depths and why I think most installers are not following the regulations
In this video I talk through a huge bug bear of mine... Prescribed Zones and chasing depths!
Now I'm not the IET so you can't take this as gospel.
However, if we look at what I think is the reasoning behind the regulations, I'm hoping you will see where I'm coming from.
I've also spent quite a lot of time researching this subject and using various sources, including an English teacher to analyse the sentence structure and wording of regulation 522.6.202, not to mention what I believe to be common sense, and I think I put forward a pretty strong case against the way that electricians are interpreting this regulation lately.
I also give a brief over view of Mary Wherry, the daughter of MP Jenny Tonge, who died back in 2004 and was speculated to be the reason for Part P's existence.
Mary was electrocuted after her husband put up a utensil rack that clipped a cable buried in the wall, which had not been run within the prescribed zone and had in fact deviated out of it by 5 degrees.
Had the cable been installed correctly, Mary might still be with us today.
As always please like - share - and subscribe to get these important messages out there, and don't forget to comment with your thoughts on the case that I have put forward.
Take care
Adrian
Vertical drops are the way to go. Householders find it easy to understand avoid putting anything above or below an accessory. It becomes hard for the home owner or tenant to grasp the whole zones issues. Not to mention I don’t want cables at ceiling level running horizontally around the top behind coving. Night mate if there’s a fault you end up destroying decorations.
Nice discussion
Good video. Do you know when the prescribed zones first became regulation? Can find no mention of them in the 14th edition am3 1976, although it seems that it was fairly standard practice for cables to be run that way for many years prior.
Thank you Andrew 🤗 I remember them being called ‘safe zones’ prior to the 17th edition
Thank you for this. As a (used to be) plumber who is now learning the electric business for some DIY work.. I have gone deep into what I am and am not allowed to do. While reading I have wondered about EXACTLY what you were describing. 150 from the return of a wall.. but that's where I attach my units etc. Can go 150 down from a roof; but I have seen both units and cornicing screwed into this. My other big question is how to meet a 50mm depth when a wall is only 30 odd mm deep. Do I just run my cables and hope for the best the next guy after me knows about proscribed vertical zones. Thank you for clarifying these rules. Great Video.
Thank you so much 🤗 You are more than welcome 🙏
Good video. I was starting to wonder what was going on, I've seen so many crazy "in the zone" installations recently. I think there needs to be examples in the regs, like there are with Rings & Radials. I generally follow what you would consider best practice, which is easy enough in most houses. However I have come across one or two where construction features mean that I do change direction within a socket, so I can avoid unnecessary building damage, or having cables in unexpected areas even if its technically "in the zone" Another I have come across is cables installed in the same way as the board at college. Out of the socket, down 6 inches, along the wall, back up to the next socket. What's all that about!? I liked your kitchen example. I have seen similar to your bad example. I note the socket behind the Extractor. I know its often still done, but I'm really not keen on that, I don't see it as accessible, and with recirculating hoods, that have filters removed/blocked come across a few hidden faults. Id rather a flex outlet/secured JB with fuse elsewhere. The sockets in the back of a cupboard is very neat I agree. I tend to bring them forward with trunking on the side. Not as discreet, but the owner cannot forget where they are, and they cannot be hidden at all, I have also fixed a few problems which is cupboard stock piling up at a switch at the back of a cupboard.
Thank you Richard 🤝 You make some valid points, and I should have mentioned in the video that I to use accessories to change direction, by going through the back box. I believe that it is good practice, because anyone taking the accessory off the wall can see the change of direction 👌
Great video, I’ve always thought the 150mm from corner zone was a bad one, I used to be a satellite TV installer and I always drilled though in the corners for the cable entry because it was neater. When I found out about the zone years later I realised I was very lucky to never hit a cable.
Exactly 😂
I have used the 150 at the top. Very handy when you can't take the floor upstairs up and can't or don't want to take the ceiling down
Regarding zig zagged zones, I will aften run the loaf side of a cooker isolator this way. Reason being if I were to run straight up, across the ceiling and down I'll be bang in line with where the hood will be drilled out. In the same area, a mate of mine does council kitchen rewires where metal conduit chased into the wall is specified for load sides of all isolators. From a cooker isolator this would need to be a 25mm conduit, which would cause issues with the chasing depths you brought up later in the video! I understand the rules are the rules, but I'm curious what you would do in these scenarios yourself? I personally am not a fan of running cables behind kitchen cabinets which leaves limited options
For me, the running of cables behind kitchen units is the lesser of all the evils and will never cause anyone any issues. In fact, if they ever change the kitchen it makes everyone’s job a lot easier
Informative video for a non sparks (me) - thanks. (Small typo on the last slide, should be "summary" :-) )
Doh!
Brilliant video mate. Thanks
You are more than welcome 🤝
Very interesting and thought provoking video,.
Thank you 🙏
Some very good valid points that will make most think about their cable routing. 👍🏻
Thank you Warren 🤝
So a socket under a window on concrete floors what's the solution. You can't run horizontally without being vertical somewhere.
That’s where you would have to resort to the 150mm safe zone at the ends of the wall. I hat sockets under windows and try to get clients to agree not to have them but sometimes you can’t avoid it
Hey Adrian we missed your brilliant videos. Wander if you doing well, which am sure you do. Hope to see you soon.
Thank you 🙏
Rear cupboard switches and sockets. I’d like to see clear door cover protectors to stop them being turned off by the contents of the cupboard.
Tell the customer to stop stuffing their cupboards full and give them some electrical tape to stick on the switch! 😂👍🏻
Sorry to bother you, adrian. I get some question about the electrical work at UK. Can i have your contact?
Is it actually permitted to run the cable from one circuit in the zone created by an accessory of another? I see this done a lot.
Thanks for the love, but it was an actual question :)
@@monikaw1179 - Horizontal OR vertical is the wording-and still open to intrepretation.
Woohoo! Yay! Completely Electrical completely agree with all that I viewed. Some of the brick loading is more complicated than that bit. I agree with the concepts and thought provoking ideas. It would depend on where the point load is or where the dynamic loads are assumed to be but yes horizontal chases are much more detrimental than vertical, unless the point load is located at the vertical chase point. Your coefficient idea? Ideally you need to consider the bending deflection, bending moments at joints and shear stress and a few others to calculate this. I'm not sure it can be this simple but if you are right then you are about to be a billionaire 🤭. For me it's straight up, down, horizontal less than 250mm. That's from my own structural calculations based on Brighton bungeroosh walls. But you are tight saying that plaster doesn't count. It kind of does because it causes a bending moment in another direction but not vertical forces on original structure... So anything better than that will be fine. To rewire a circuit it needs to be straight up or down or horizontal in tube between obvious points for me.. I hate prescribed zones. It promotes laziness imo. It used to be so bloody easy. Straight up or down... Now I'm scared to drill through a wall because who bloody knows where they all are??? Takes me ages to carefully use probe detectors and chip away and all sorts of other nonsense just to get on with a simple job 🤬 Happy to show you the structural calcs once I've had some time to revise. 🤭 Approved docs are not stat. Building regulations are stat which are not the same. I've been looking a lot at these due to grenfell stuff but yeah approved docs... they are same status as bs7671 really. Implied in guidance but not law. Totally agree about surface horizontal and chased vertical. 👍 Chasing vertical is easier. We need to talk about editing but I love this video 😂. I'm no better but I know the solution 😂..... Great stuff buddy 👍👏
Thanks Craig 🤝🤗
Great video.
Thank you 🤗
I think if everyone knew where the zones are, this would solve a lot of problems and make one think twice before making a hole. The Mary Wherry case I believe was the cable veered off at a 5% angle away from the zone and was not RCD protected either.
That is correct, however if it had not veered out of zone they would not have hit the cable. RCD’s are additional protection
@@Pure_electrical_training yes additional protection and keep within the zone would be implemented now but still they should have kept within the zone, going round the side of the box although is wrong but cable's being there would be more obvious than cable zones to a DIYer.
⭐️
Hiya would love to chat with you regarding my current position because no body wants to seem to give me a straight answer , j am in a domestic installer course and have learnt that I have basically had my pants down , I learnt the hard way and now I don’t know what to do
Of course, I’m here to help in any way that I can. Email me your situation and I’ll get something together 🙌
No problem, where can find your email ?
Adrianepdavey@gmail.com
Hey how do i contact you adrian
What can I do for you?
@@Pure_electrical_training w as looking to start my journey as a electrcian within the industry
And do the level 2 and 3 with 18th edition
Good information, I am not a qualified electrician yet but your diagram at 25:11 will it not be better to fuse spur the bottom sockets so at least they can be isolated from the fuse spur switch and it's easier to follow the prescribed zones ? I am sure the picture which is shown in 21:47 is from CJR ELECTRICAL kzhead.info/sun/fdaEeMlqbXVjl3k/bejne.html. lol
Prescribed zones aren't know by the vast majority of UK population id hazard a guess at over 99.9% , rendering them useless for the average homeowner.
Exactly my point, which is if we are lucky they will just take off a face plate to see which way the cable is pointing, and avoid that area. That is the principle behind the prescribed zones
The 150mm rule from corners is for the lazy boys👍🏻🤣 . Never use them no need
Agreed 👌
Where to start? I fundamentally disagree with most of what you have stated and I think you have misunderstood the reg. You absolutely CANNOT extend the prescribed safe zone to the other side of a wall to facilitate a cable drop for an accessory on the other side of the wall (from the cable drop), potentially fatal, how can anyone know where the cables run? unless you sink a box and fit a blanking plate, that said where a wall is 100mm or less thick then you must take into account the prescribed zones on BOTH sides when considering drilling or fixing anything on the wall. It is wrong to ask non electrically skilled people to unscrew an accessory to try and determine which way the cables enter, better to make EVERY non electrically skilled person assume that there is a wire in EVERY prescribe safe zone and NEVER to drill in these areas. Correct to say you should not run cables and change direction along that run before it gets to an accessory. We need better education of prescribed safe zones, make it a requirement on EVERY C&G level 2 & above exam for ALL construction trades and put the info on the packaging of ALL things that may need fixing to a wall, floor or ceiling. Putting circuit accessories in cupboards is very bad form, especially any form of isolator such as a cooker switch, these items should be "readily accessible" and in the back of a cupboard, even mounted high up, simply does not meet this requirement, there will always be something in the cupboard on the shelf that will obscure or otherwise cover the accessory, do not do this, even when you have a "solid?" 18mm backing to the unit. The prescribed safe zones shown in the 2nd diagram in your video is to ensure the safety of non electrically skilled persons (and quite frankly, idiots) and you absolutely SHOULD assume there may be cables in EVERY zone, that way you are SAFE. Judging by some of the other comments I am correct to say we need better education, some people who should have know about prescribed safe zones simply did not, and seemed to have just been lucky !! Sadly we live in a world where we cannot assume everyone is sensible, reasonable and can be trusted to do the right thing so we need rules (around things like electricity and gas) that cater for "the lowest common denominator" therefore ALL non electrically skilled people SHOULD ALWAYS assume there is a cable in EVERY prescribed safe zone, if you want to put a screw in the wall in a prescribed zone then get a competent and conscientious electrican to formerly certify (name, address, Part P registration details etc) it safe to use fixings in a specified area
Then we can agree, to disagree and that’s O.K We aren’t going to agree on everything and I stand by my video 👍