I've never used a 16mm back box and never realised that the 20mm grommets fitted the oval cutouts! Great tip. The rethreading tools are cheap to buy and incredibly useful.
I'm not an electrician; but I still find your channel most educational and you are a man after my own heart when it comes to describing a certain class of "tradies" and "no brainers". Keep up the good work. Just out of interest I once made 8500 rammed pise bricks, one at a time, to build a home. As it was in the bush and not connected to mains water I could legally do all the plumbing. Plus, it was in the days when electrical work had to be inspected by an official inspector from the then owned state electricity commission (a State in Australia). I had a certificate in basic electronics and the official regulations book on electricity wiring and went ahead and wired the whole house. I was able to get a friendly qualified electrician to do the mains connection and fuse board etc. Of course it helped my partner's father was a manager for the commission and when the inspector arrived and climbed into the roof cavity he exclaimed, "I have never seen a neater wiring job", I think my exact measurements between retaining clips and the like might have given the game away. Nonetheless, the work was certified and the mains connected.
How on earth did you make those boxes appear? I assumed you just edited the video together but you didn’t move or miss a beat. LOL. You are the dead pan king. Thanks John it’s always a pleasure to watch your videos. Regards Chris
He filmed it twice then overlaid each video, left side normal filming, right side stop motion. He filmed the normal side (left) with the boxes already there.
When we put those in the wall with conduit we don't use glands. Don't forget the conduit fits through the 20mm hole anyway, once the conduit is nailed on its going nowhere and when the fill is back well! Its really going no where.
Very comprehensive video! I'm gradually fitting metal backboxes in my house, to replace the existing sockets and switches that have wooden boxes behind them!
Reminds me of a funny story: In my old house I had two back-boxes side-by-side in the living room. One was a light switch, the other a dimmer. One day I decided to change the dimmer. When I took the old dimmer off one of the screws was plastic. It seems this was some kind of safety 'mitigation' because directly underneath the screw was the supply cable, going out the hole beneath the tab!
Great video and explained an issue I had replacing a switch in my parents house. Socket screws changed in the 60's and kept stripping the new ones. M3.5 x0.6 Vs 4BA. At the time I just cleaned up the old heads and reused them.
The knockouts aren't welded. They're made using what I've always know as 'punch and return' - the punch has a gap that leaves the tab and after punching the knockout is pressed back into place.
I used to work for a company that made pressed electronic components and this item looks like a prime candidate for a process like they would use. They made a “progression tool” into which you feed metallic strip. What you’ll probably find is that these boxes are punched out of a strip and progressively shaped. So I’d expect the hole would be punched out before the tabs are then bent into position. th-cam.com/video/QcYFgoO_NDQ/w-d-xo.html th-cam.com/video/9Da_HDSbwE0/w-d-xo.html
Mk 2amp outlets used top and bottom screws,regarding box depth when as an apprentice i was told on brickwork to be plastered ,thickness of a file was required to be protruding from chase(or else!),promptly the plasterers would coat it with about 50mm of plaster, how I laughed as I dug my way through it to get to the box!
I had the joy last week of applying a bit of TLC to an ex-rental property on behalf of the family who'd just bought it. Typically, the 45A DP oven isolator (1 gang for no good reason) was inside a kitchen cupboard attached to the remains of a brittle 47mm white pattress. A disaster waiting to happen really as the mess wasn't easy to see until your eyes were
I thought I was seeing things when they slowly started appearing. Also I use 35mm boxes for everything whenever possible (makes 2nd fix much easier). The only exception are things like cooker switches, cooker connection units, etc where you pretty much need 47mm back boxes.
Hey JW could you do an experiment with twin and earth cables For example show the heating effects of 50A through 1m of all domestic size cables(1mm,2.5mm,6mm,maybe a peice of 10mm) then maybe 100A through them, after then maybe 200A or more etc I think it would make for a very interesting watch. Keep up the good work JW.
@@zippymo672 haha no JW clearly knows what he is doing and can create a safe controlled environment to demonstrate the experiment. Give the guy some credit.
i think the reason single boxes still have holes at the top & bottom is because they are sqaure not rectangular it would be much easier for someone to mistakenly put the thing in the wall at 90 degrees to what it should be and then if it was plastered you'd be screwed (no pun intended)
Great video. I'm hoping it will be ok to puch oval conduit unti the boxes and not uae grommets. Also, I drill holes to screw boxes to block work but put gyproc bonding in the cut out hole first and then screw metal boxes in. Very solid 😊
I remember I once made the mistake of installing two singles side by side. Fortunately I had only spent 3 hours chisselling a wall out to fit them!!! 😂🤣😅😭😭😭
I find the best tool for doing the metal knockouts is the handle from an old metal claw hammer which just so happens to be about 18 to 19mm and is still stout enough to get a good clout from your chosen thumb detector.
Those knockouts are aren't welded JW, special punches and dies are used which have a little notch so that a little tab is left when the holes are partially punched through, probably done on a power press with a custom made tool set which will stamp out the whole blank in one hit but could also be done on a cnc machine. The knockouts are punched to a set depth so that they're almost completely through but not quite.
One thing not mentioned in the video is that the regs state it's not necessary to use the box earth terminal as long as the box has one fixed lug. Most boxes do. The box is still unearthed via the socket screws. Some electricians still earth the box though regardless.
You didn't show any kind of old work electrical boxes. Although, I don't know if you have such things. In America, they have rotatable wings to hold the box securely in sheetrock in instances where you want to put a box in where there was none without having to rip out the plaster. You can also get boxes in metal, PVC, and thermoset.
The British equivalent to what you describe is a so-called dry lining box or cavity box. The wings are secured by the fixing screws of the item you are installing in the box.
CJR used the extension boxes on sockets where the wall was to receive an internal layer of insulation. The video showing this was his work at a university.
That's interesting. Here in the US all our boxes are at least 2" (50 mm), and up to 3 3/4" (95 mm), but I suppose the vast majority of installations are in stud walls, so it doesn't matter so much. Some boxes come with nails already mounted on them, so you just nail them to the stud.
I find the triple gang backboxes (and socket outlets) best for use in the kitchen. Double sockets never seem enough...However they are relatively hard to source.
John Coops - Possibly! The French nominal sizes could be expressed as 5/8”, 8/8”, 11/8” and 15/8” in English, so there is a sort of logical progression. More likely, with the deepest size, they were concerned about avoiding cutting into too much of the depth of a wall or stud. All I can say is that the new 47mm nominal back box in front of me actually measures 48mm deep or exactly 1 7/8”, and the 1960 socket back box I recently took out in my house was exactly the same dimensions as a modern day one. Also I’ve had no problem fitting new faceplates to old back boxes.
I find it interesting to have gotten two somewhat conflicting answers, with Supersparks making a distinction based on the material the box is made from and Stuart Mchale reserving the word pattress for surface-mounted boxes. So, nobody knows? (A surface-mount(?) plastic box was shown at 22:34, but still JW never said pattress.)
@@ropersonline yea surface mounted basicly a patress is a plastic containment used where an accessory can't be mounted flush. You can also get round ones for luminaires, we call them "biscuits" for some unknown reason.
Years ago, B&Q used to sell self branded crappy back boxes were the screw lugs used to break off due to using low quality metal and the earth screw was not big enough to properly grip 1mm earth wires. No idea if they are still making these.
Thanks very much. Looks like a very sophisticated system with the possibility to have direct connection to conduits. We in Germany have only plastic backboxes. Is there any known reason why they are made from metal in the UK, I guess there is an advantage somehow?
You can tell John lives in an old house and has the luxury of fitting anything more than a 25mm! I would have to hack breeze blocks to do that. I’d rather leave them in one piece to support the house structure! You can get spacers to space sockets out a little if needs must. Oval grommets are available for 16mm boxes. Shame you didn’t show a dry lined box for modern internal walls.
Chiselling out another 10 or 20cm depth of breeze-block will only have a minuscule effect on the wall's load bearing capability. It's just a bit tedious. I had to put some deeper back-boxes in to fit some dimmer switches and it took about 30 minutes. A hammer (or, better, SDS) drill a lot of holes around the periphery to a set depth and then chisel it out. Easy enough with thermalite type block, a real pain with ancient breeze block typically made with coal ash or the like. The trickiest bit was getting the old back boxes out, and they can be a bit tight. It's also necessary to be very careful not to damage the cable.
I don't know about "morons" putting backboxes in to deep and not allowing for the extra depth. There's one extremely common reason why longer screws have to be retro-fitted and that's when a wall, typically a splash back in a kitchen is tiled at some later date. That extra tile and adhesive thickness can easily be enough such that the existing screws won't reach. Yes, it might be possible to remove the old back box and replace it with a deeper one, but can be a real pain if it's plasteredin and there's a decent chance of damaging cables.
Wow. Those are extremely shallow by US standards. Normal US boxes are about 3-4" deep. Height and width are about the same. US style receptacles and switches sit inside the box, with a flush plate over the front. US boxes are normally nailed to the side of a stud and the sheet rock put on top and a hole cut out for the box opening. I'm also surprised that there's no requirement to clamp the wires where they enter the boxes. Romex aka NMB is required to have a clamp applied at the entrance to the box.
From what I have seen - many UK homes walls are normally made from brick or stone so I guess this explains why they use shallow ones unlike the hallow walls you folks have in the US. Also unlike US module socket designs - the UK ones are normally integrated with the the faceplate.
That's what I gather too, my walls are all solid (no cavity) and there just isn't much room for anything. Some use surface pattress mounting due to lack of in wall space and ancient building materials that like to fall off when disturbed.
Why would clamping be required? The cable runs in conduit embedded in the wall, and the cable is going nowhere. It isn't as if the cable is going to move.
In wood stud framed walls it's very common to use sheathed cable in house wiring in North American rather then conduit, or armored cable, unless the wiring is surface mounted. This sheathed cable is run along framing members, such as studs or joists, and secured with staples to prevent movement, or threaded through holes drilled through the studs or joists, depending on where they are needed. When the ends of the cables are threaded into an electrical device box, the sheath is clamped to the back of the box, and about 6'' or more of the sheath is stripped off, exposing the wires. Sometimes it's called "Romex" or "Loomex", which are vernacular names for sheathed cable that were originally manufacturers trademarked names for the same.
@@OlegKostoglatov In the UK cables in the walls are meant to be run in what's called "safe zones", which are either horizontally or vertically from any electrical fitting, such as an outlet or switch. Alternatively, there are "safe zones" within a fixed distance of the floors, ceilings or any corners (150mm or 6 inches) wide. All this is meant to avoid the possibility of somebody putting a screw or other fixing through a live cable. Of course, where an outlet can be installed next to a stud, then it's easy enough to run the cables up that, but the practice is almost always (as far as I can tell) to use conduit in order to allow cables to be pulled through or replaced later, perhaps if they have been damaged. Cables run outside the "safe zones" have to be at least 50mm from a surface and protected in metal conduit. The generic grey-sheathed "twin + earth" in the UK is very similar to Romex type cabling used in North America save for the colour coding. There are, of course, sheathed cables with more cores available. There are different rules for running cables in ceiling voids. For the most part, UK houses are not built with wood framed external walls (although there are some). However, internal walls are most commonly stud.
25mm type usually means a pretty difficult removal of brickwork by drilling, chiselling, angle grinding...unless there's an easier way..? If you've got 10mm of plaster direct on brick, you need to remove slightly more than 15mm of brick. Messy!
I used a chisel which had a slotted end suitable for fitting a comb bit to. It was ideal for cutting a half-inch trench in brick or block without disturbing the main structure. Comb bits are cheap, comb chisels are still out there, google is your friend.
The back box I have is very old, and small light switch, it has two conduit coming down into the top. What tool do you need to remove the box from the conduit... Is there a video that shows how to do this? The new smart switch is to deep for the box
If it's round conduit, then one of these: www.cef.co.uk/catalogue/products/1931159-190mm-conduit-bush-wrench to unscrew the brass bushes which secure it into the box.
Someone may have mentioned it already but when using single core cables with a metal box, both conductors (live and neutral) of the same circuit should go through the same hole. Otherwise, magnetic fields could be set up if different holes are used and therefore a loss of power, apart from the fact that it does not comply with the regs.
Lazy council where I live did a cheap method by removing a single socket outlet and replacing it with a double socket plug outlet, my bedroom developed a problem within a few weeks with the left switch f*cking up and staying on.
A surprisingly interesting video! I do have one question though... if you have a single socket and its fcu fitted to the same dual back box, how do you run the cable between them. There's typically no knockouts on the central divider so would you use the top (or bottom) knockouts to run a short length of cable? It's would be in a preferred zone so I'm guessing should be ok but I just wanted to check what best practice would suggest.
Answering my own question after coming back from Screwfix, in case anyone else was pondering what I was pondering! The central piece that divides dual back boxes into two is comprised of two parts - a facing strut that has screw holes into which you can screw faceplates, and a central 'wall' that physically divides the box into two. What I didn't realise is that although there are no knockouts in this central wall, it can be removed altogether whilst leaving the other piece in place. Which would seem sensible! 🤪
Great video JP. On a slight tangent; are there any regulations against passing through back boxes with cables from different circuits? for example if you have a light switch directly above a ring main socket, could you run the ring main cable down with the lighting cable through the light switch back box and continue down to the plug socket, to stay in the prescribed zone?
No, you may not do that. 522.6.202 A cable installed in a wall or partition at a depth of less than 50 mm from a surface of the wall or partition shall: (i) be installed in a zone within 150 mm from the top of the wall or partition or within 150 mm of an angle formed by two adjoining walls or partitions. Where the cable is connected to a point, accessory or switchgear on any surface of the wall or partition, the cable may be installed in a zone either horizontally or vertically, to the point, accessory or switchgear. Where the location of the accessory, point or switchgear can be determined from the reverse side, a zone formed on one side of a wall of 100 mm thickness or less or partition of 100 mm thickness or less extends to the reverse side, or (ii) comply with Regulation 522.6.204 Note "Where the cable is CONNECTED TO...". Not "passing through" - it has to be *connnected to* the accessory for the accessory to create a zone for it.
I have an ex council house I bought 30 years ago every light switch was the 16mm or the Imperial equivalent I think the reason they used these is because the plaster is the same thickness
Ha, maybe it's just me who says that, some people I know have a yellow double socket which is crooked in every plane in the middle of the wall in their new kitchen
In my house, which appears to have had a council rewire some time ago, 16mm backboxes are used for lightswitches. One of the issues though is that the rewire was done using the existing metal conduit in singles (including earth wires). This means I have ~40mm of depth from back of backbox to the plaster surface, which makes removing and refitting awkward (things don't quite lineup). Replacing these is also difficult as I've not seen single boxes with a centre knockout for cable entry, what would you do ?
I don't know if you have and equivalent in Britain but there are hole punches available in North America for punching larger holes in sheet metal, specifically for electrical boxes. A company called Greenlee makes sets of them, but they are not the only ones. There are two halves tightened together with a 1/4'' bolt, and as it is tightened it sheers a hole through the sheet metal. If you are putting a new box this may work, but not in an existing one already fastened into the wall as you need to access both sides to use it, so a bi-metal hole saw might be the answer there.
@johnward I've come across a load of single back boxes with double face plates are they OK to ve like that or must i use a double with double or single with single
There are converter sockets which are doubles that fit over a single box, they are ok to use. Otherwise no, as a normal double won't fit on a single box.
On new installations start at one end and screw in one at a time. For a socket, the length of conduit to the socket is installed first, then the coupler is screwed on, then the brass bush is screwed into the coupler. For the rare situation where two pieces of conduit need to be joined on an existing system between two existing items, the thread on one is cut extra long so a locknut and coupler can be screwed on completely, the two pieces are then installed and the coupler threaded back over the joint with the locknut securing it. The exposed thread then has to be painted to prevent corrosion.
Great video ty. In your opinion do you need to separately earth metal back boxes or is the connection through the screw onto the fixed lug sufficient. I have always tended to supplementary bond them to the face plate earth connection, but is this ott?
Connecting via one fixed lug is permitted, but like many things there is the choice between doing the absolute minimum required, or doing a decent job of it.
Can anyone explain to me (complete novice) why after I disconnected a faulty transformer in my ceiling light some of my other lights don't work but some do - is it as simple as the order in which the cable goes to them? I presumed it would be all or none if it is a ring circuit... or perhaps that's the answer, they're on a separte loop off the main circuit?
No, but if you really want a triple socket in plasterboard, you can get metal flanges to fit a metal box into plasterboard. MK part number 800ZIC. Or just fit two double sockets.
Honestly , just use 35 for everything(or deeper) . why bother making your life harder ? Oh and top tip, if your trying to line up 2 sockets just use conduit between them , it will lock them in place level :)
Brass bushes in 20mm holes, 14.30, did you see how poorly and loose fitting the hex nut end was. I remember back in the early 80's before metric brass was used how the hex nut end used to cover the actual hole. Nowadays you have to put a 20mm lock ring under the hex end to stop it popping thru' the hole. Brass bushes are terrible quality now
OK the more video's you do on UK standards the more it lookes like the UK has had 0 evolution for the past 40 years! not only are those boxes metal but you can't even fit them together in any sensible way!
Not sure what you mean. Metal boxes are strong and fire proof so advantageous. We do fit surface mounted plastic boxes, or plastic cavity boxes. Metal boxes aren't an issue as long as they are grounded. Trust me... there has certainly been many changes over forty years. Our IEE regulations are VERY stringent.
Plastic boxes are available, but galvanised steel is more fire resistant. As for fitting them together, there's really not much point as sockets/outlets and switches tend to come in standard sizes, and overwelmingly single and doubles with a very few triples. I'm leaving out special purpose ones like outlets for electric cookers and so on.
what's your deal with fire ? are your house made from matchstick? A sensibly maintaine electric istalation dose not catch fire ever in the first place! Also I would be so shure metal boxes are more fire-resistant than plastic. Finally when I say mont them together I mean that if I go to any modern electric supplier I will be able to get enlessly clipable box therfore creating the disiered shape with out any problems
@@martinw245 I'm sorry but the fact you still use rings and have the most mainquiest plug in existence ( that things might be safe but it's also a pain in the ass to do anything with it) makes me encline to say that you haven't evolved that much. seriously what is wrong with the europlug?????
Just wanted to say I enjoyed the boxes magically appearing in the seamless jump cuts at the start of the video. Don't know why but made me giggle!
Hehe. Nice one on the magically apearing boxes. :)
I enjoyed that too haha
Indeed
How dare he try to fool me!
JW the dead-pan magician!
Thank you for the information straightforward no messing answered all my questions
Great now a subscriber
How does one manage to make a 24-minute video about back boxes?? This is indeed a feat.
I've never used a 16mm back box and never realised that the 20mm grommets fitted the oval cutouts! Great tip. The rethreading tools are cheap to buy and incredibly useful.
I'm not an electrician; but I still find your channel most educational and you are a man after my own heart when it comes to describing a certain class of "tradies" and "no brainers". Keep up the good work. Just out of interest I once made 8500 rammed pise bricks, one at a time, to build a home. As it was in the bush and not connected to mains water I could legally do all the plumbing. Plus, it was in the days when electrical work had to be inspected by an official inspector from the then owned state electricity commission (a State in Australia). I had a certificate in basic electronics and the official regulations book on electricity wiring and went ahead and wired the whole house. I was able to get a friendly qualified electrician to do the mains connection and fuse board etc. Of course it helped my partner's father was a manager for the commission and when the inspector arrived and climbed into the roof cavity he exclaimed, "I have never seen a neater wiring job", I think my exact measurements between retaining clips and the like might have given the game away. Nonetheless, the work was certified and the mains connected.
probably the most in depth explanation of back boxes there is. . . as supplied to you by our box of tricks and useful information. . JW
Very clear and informative video well done
Your delivery is always precise and informative. If only other lecturers were the same I would have done better at college!
How on earth did you make those boxes appear? I assumed you just edited the video together but you didn’t move or miss a beat. LOL. You are the dead pan king. Thanks John it’s always a pleasure to watch your videos. Regards Chris
Simon Jenkins I guess Johns not telling but that would spoil the magic. Your explanation sounds right. Thanks Regards Chris
He filmed it twice then overlaid each video, left side normal filming, right side stop motion. He filmed the normal side (left) with the boxes already there.
16mm boxes are for when you don't want to chisel brickwork out :-D
When we put those in the wall with conduit we don't use glands. Don't forget the conduit fits through the 20mm hole anyway, once the conduit is nailed on its going nowhere and when the fill is back well! Its really going no where.
i have been wating such as this video from along time and we usual use boxes with size 35 mm and 47mm . thanks john and i enjoyed your great video
Very comprehensive video! I'm gradually fitting metal backboxes in my house, to replace the existing sockets and switches that have wooden boxes behind them!
I've got those lol
In North America, single boxes have removable sides so that 2 or more can be connected together to make double or triple wide boxes.
Reminds me of a funny story: In my old house I had two back-boxes side-by-side in the living room. One was a light switch, the other a dimmer. One day I decided to change the dimmer. When I took the old dimmer off one of the screws was plastic. It seems this was some kind of safety 'mitigation' because directly underneath the screw was the supply cable, going out the hole beneath the tab!
I think the video we all want to see is JW knocking out a tune on the piano.
Great video and explained an issue I had replacing a switch in my parents house. Socket screws changed in the 60's and kept stripping the new ones. M3.5 x0.6 Vs 4BA. At the time I just cleaned up the old heads and reused them.
Agreed on the 16mm box. I only ever used them on light fed switch's where necessary. Like metal in the way of chasing etc
When mounting boxes next to each other, the spacing is 1 inch between screwthreads then the accessories will butt together perfectly
1) Accessories butted together look as ugly as an ugly thing which is very ugly.
2) Connect your boxes together with 20mm conduit couplers and bushes.
The 16mm boxes are useful for AV/RF connectors.
The knockouts aren't welded. They're made using what I've always know as 'punch and return' - the punch has a gap that leaves the tab and after punching the knockout is pressed back into place.
How do you account for the circularity of the bit still connected ? Perhaps some are done as you say and others are welded ?
I used to work for a company that made pressed electronic components and this item looks like a prime candidate for a process like they would use.
They made a “progression tool” into which you feed metallic strip. What you’ll probably find is that these boxes are punched out of a strip and progressively shaped. So I’d expect the hole would be punched out before the tabs are then bent into position.
th-cam.com/video/QcYFgoO_NDQ/w-d-xo.html
th-cam.com/video/9Da_HDSbwE0/w-d-xo.html
Mk 2amp outlets used top and bottom screws,regarding box depth when as an apprentice i was told on brickwork to be plastered ,thickness of a file was required to be protruding from chase(or else!),promptly the plasterers would coat it with about 50mm of plaster, how I laughed as I dug my way through it to get to the box!
I had the joy last week of applying a bit of TLC to an ex-rental property on behalf of the family who'd just bought it. Typically, the 45A DP oven isolator (1 gang for no good reason) was inside a kitchen cupboard attached to the remains of a brittle 47mm white pattress. A disaster waiting to happen really as the mess wasn't easy to see until your eyes were
John loves playing with his green screen, lol, loved the way the boxes magically appeared one by one at the start.
16mm switch boxes do come in handy sometimes, certainly not next to useless.
I thought I was seeing things when they slowly started appearing. Also I use 35mm boxes for everything whenever possible (makes 2nd fix much easier). The only exception are things like cooker switches, cooker connection units, etc where you pretty much need 47mm back boxes.
Excellent explanation, answered some of my queries.
Hey JW could you do an experiment with twin and earth cables
For example show the heating effects of 50A through 1m of all domestic size cables(1mm,2.5mm,6mm,maybe a peice of 10mm) then maybe 100A through them, after then maybe 200A or more etc I think it would make for a very interesting watch. Keep up the good work JW.
...and set his house on fire?
@@zippymo672 haha no JW clearly knows what he is doing and can create a safe controlled environment to demonstrate the experiment. Give the guy some credit.
@@danjason2167 lolll I know. He is a good bloke. I wish I was learning off him in the trade.
What happens with 1mm² is covered in this video: th-cam.com/video/bBYHtBPbBJE/w-d-xo.html
that's more @photonicinduction territory i think
Nice video, thanks for taking the time to make it.
i think the reason single boxes still have holes at the top & bottom is because they are sqaure not rectangular it would be much easier for someone to mistakenly put the thing in the wall at 90 degrees to what it should be and then if it was plastered you'd be screwed (no pun intended)
Apart from the lugs on either side 😂
@@stuartmchale4482 yes exactly thats the point im making
Great video. I'm hoping it will be ok to puch oval conduit unti the boxes and not uae grommets.
Also, I drill holes to screw boxes to block work but put gyproc bonding in the cut out hole first and then screw metal boxes in. Very solid 😊
Big Clive did a video on these today too!
I remember I once made the mistake of installing two singles side by side. Fortunately I had only spent 3 hours chisselling a wall out to fit them!!! 😂🤣😅😭😭😭
Great video JW.. Very informative. Should have saved this one for boxing day. 😁
20:16 i don't know why I'm watching this I'm just going through johns catalogue and then this amazing tip gets dropped. nice one
I find the best tool for doing the metal knockouts is the handle from an old metal claw hammer which just so happens to be about 18 to 19mm and is still stout enough to get a good clout from your chosen thumb detector.
Those knockouts are aren't welded JW, special punches and dies are used which have a little notch so that a little tab is left when the holes are partially punched through, probably done on a power press with a custom made tool set which will stamp out the whole blank in one hit but could also be done on a cnc machine. The knockouts are punched to a set depth so that they're almost completely through but not quite.
Are steel and plastic conduit used only with flexy single cores? Have you done videos showing oval conduit?
One thing not mentioned in the video is that the regs state it's not necessary to use the box earth terminal as long as the box has one fixed lug. Most boxes do. The box is still unearthed via the socket screws. Some electricians still earth the box though regardless.
You didn't show any kind of old work electrical boxes. Although, I don't know if you have such things. In America, they have rotatable wings to hold the box securely in sheetrock in instances where you want to put a box in where there was none without having to rip out the plaster. You can also get boxes in metal, PVC, and thermoset.
The British equivalent to what you describe is a so-called dry lining box or cavity box. The wings are secured by the fixing screws of the item you are installing in the box.
CJR used the extension boxes on sockets where the wall was to receive an internal layer of insulation. The video showing this was his work at a university.
That's interesting. Here in the US all our boxes are at least 2" (50 mm), and up to 3 3/4" (95 mm), but I suppose the vast majority of installations are in stud walls, so it doesn't matter so much. Some boxes come with nails already mounted on them, so you just nail them to the stud.
Thanks John another great video
John, We across the pond can not use the conduit coupling with two fittings. The coupling is listed to connect two conduits, not two fittings.
Very informative, Thank you.
I find the triple gang backboxes (and socket outlets) best for use in the kitchen. Double sockets never seem enough...However they are relatively hard to source.
I used to know a guy who would Install a double socket into a double 16mm metal box . I think it was an appelby 633. Don't know how but he did it .
Lovely bit of conduit. I think the globe should rotate .
I bought the cutter for my drill.
I now have big round holes in my walls.
Lol.
I wonder why they decided on 47mm and not 50mm for the deep box? Very educational video.
The dimensions will all have been British units originally, so 1 7/8” in reality, with the nearest French equivalent being 47mm.
@@Benzknees Makes sense. Thanks.
@@Benzknees - so they were drunk when they decided to make them 1 7/8" rather than 2" deep?
John Coops - Possibly! The French nominal sizes could be expressed as 5/8”, 8/8”, 11/8” and 15/8” in English, so there is a sort of logical progression. More likely, with the deepest size, they were concerned about avoiding cutting into too much of the depth of a wall or stud. All I can say is that the new 47mm nominal back box in front of me actually measures 48mm deep or exactly 1 7/8”, and the 1960 socket back box I recently took out in my house was exactly the same dimensions as a modern day one. Also I’ve had no problem fitting new faceplates to old back boxes.
I'm kind of impressed you went through that entire video without ever mentioning the word pattress once. Is it a regional preference thing?
Patress is used for plastic boxes not metal
Surface mounted
I find it interesting to have gotten two somewhat conflicting answers, with Supersparks making a distinction based on the material the box is made from and Stuart Mchale reserving the word pattress for surface-mounted boxes. So, nobody knows? (A surface-mount(?) plastic box was shown at 22:34, but still JW never said pattress.)
@@ropersonline I meant surface plastic.
@@ropersonline yea surface mounted basicly a patress is a plastic containment used where an accessory can't be mounted flush. You can also get round ones for luminaires, we call them "biscuits" for some unknown reason.
Years ago, B&Q used to sell self branded crappy back boxes were the screw lugs used to break off due to using low quality metal and the earth screw was not big enough to properly grip 1mm earth wires. No idea if they are still making these.
I think they just re-branded it all to the "Diall" name and upped the price!
Kingfisher International = crap
Thanks very much. Looks like a very sophisticated system with the possibility to have direct connection to conduits. We in Germany have only plastic backboxes. Is there any known reason why they are made from metal in the UK, I guess there is an advantage somehow?
You can tell John lives in an old house and has the luxury of fitting anything more than a 25mm! I would have to hack breeze blocks to do that. I’d rather leave them in one piece to support the house structure! You can get spacers to space sockets out a little if needs must. Oval grommets are available for 16mm boxes. Shame you didn’t show a dry lined box for modern internal walls.
Chiselling out another 10 or 20cm depth of breeze-block will only have a minuscule effect on the wall's load bearing capability. It's just a bit tedious. I had to put some deeper back-boxes in to fit some dimmer switches and it took about 30 minutes. A hammer (or, better, SDS) drill a lot of holes around the periphery to a set depth and then chisel it out. Easy enough with thermalite type block, a real pain with ancient breeze block typically made with coal ash or the like.
The trickiest bit was getting the old back boxes out, and they can be a bit tight. It's also necessary to be very careful not to damage the cable.
For me, the two singles is very common here because the normal double socket cost around 26$ so we use 2 singles
Anyone know how to remove the nail from the back when the back box is nailed to a piece of wood behind? This is in a plasterboard stud wall.
Great video 👍
I don't know about "morons" putting backboxes in to deep and not allowing for the extra depth. There's one extremely common reason why longer screws have to be retro-fitted and that's when a wall, typically a splash back in a kitchen is tiled at some later date. That extra tile and adhesive thickness can easily be enough such that the existing screws won't reach.
Yes, it might be possible to remove the old back box and replace it with a deeper one, but can be a real pain if it's plasteredin and there's a decent chance of damaging cables.
Wow. Those are extremely shallow by US standards. Normal US boxes are about 3-4" deep. Height and width are about the same. US style receptacles and switches sit inside the box, with a flush plate over the front.
US boxes are normally nailed to the side of a stud and the sheet rock put on top and a hole cut out for the box opening.
I'm also surprised that there's no requirement to clamp the wires where they enter the boxes. Romex aka NMB is required to have a clamp applied at the entrance to the box.
From what I have seen - many UK homes walls are normally made from brick or stone so I guess this explains why they use shallow ones unlike the hallow walls you folks have in the US. Also unlike US module socket designs - the UK ones are normally integrated with the the faceplate.
That's what I gather too, my walls are all solid (no cavity) and there just isn't much room for anything. Some use surface pattress mounting due to lack of in wall space and ancient building materials that like to fall off when disturbed.
Why would clamping be required? The cable runs in conduit embedded in the wall, and the cable is going nowhere. It isn't as if the cable is going to move.
In wood stud framed walls it's very common to use sheathed cable in house wiring in North American rather then conduit, or armored cable, unless the wiring is surface mounted. This sheathed cable is run along framing members, such as studs or joists, and secured with staples to prevent movement, or threaded through holes drilled through the studs or joists, depending on where they are needed. When the ends of the cables are threaded into an electrical device box, the sheath is clamped to the back of the box, and about 6'' or more of the sheath is stripped off, exposing the wires. Sometimes it's called "Romex" or "Loomex", which are vernacular names for sheathed cable that were originally manufacturers trademarked names for the same.
@@OlegKostoglatov In the UK cables in the walls are meant to be run in what's called "safe zones", which are either horizontally or vertically from any electrical fitting, such as an outlet or switch. Alternatively, there are "safe zones" within a fixed distance of the floors, ceilings or any corners (150mm or 6 inches) wide. All this is meant to avoid the possibility of somebody putting a screw or other fixing through a live cable.
Of course, where an outlet can be installed next to a stud, then it's easy enough to run the cables up that, but the practice is almost always (as far as I can tell) to use conduit in order to allow cables to be pulled through or replaced later, perhaps if they have been damaged.
Cables run outside the "safe zones" have to be at least 50mm from a surface and protected in metal conduit.
The generic grey-sheathed "twin + earth" in the UK is very similar to Romex type cabling used in North America save for the colour coding. There are, of course, sheathed cables with more cores available.
There are different rules for running cables in ceiling voids.
For the most part, UK houses are not built with wood framed external walls (although there are some). However, internal walls are most commonly stud.
Metal Pattress Boxes is the correct title
lol he's getting more and more entertaining on the video effects XD
Hi John would you be able to do a video on joists for passing cable and conduit through, and what you are and arnt allowed to do please?
Why back boxes out of metal? Metal and electricity - is that not a potential hazard? Also, over time don’t they all corrode? What am I missing?
The boxes are galvanised steel, walls are not generally wet either so corrosion is not a problem.
25mm type usually means a pretty difficult removal of brickwork by drilling, chiselling, angle grinding...unless there's an easier way..?
If you've got 10mm of plaster direct on brick, you need to remove slightly more than 15mm of brick. Messy!
I used a chisel which had a slotted end suitable for fitting a comb bit to. It was ideal for cutting a half-inch trench in brick or block without disturbing the main structure. Comb bits are cheap, comb chisels are still out there, google is your friend.
@@brando6BL Thanks for the tip, cheers Jerry
£4.28 Toolstation!
Thanks John
The back box I have is very old, and small light switch, it has two conduit coming down into the top. What tool do you need to remove the box from the conduit... Is there a video that shows how to do this? The new smart switch is to deep for the box
If it's round conduit, then one of these: www.cef.co.uk/catalogue/products/1931159-190mm-conduit-bush-wrench to unscrew the brass bushes which secure it into the box.
Someone may have mentioned it already but when using single core cables with a metal box, both conductors (live and neutral) of the same circuit should go through the same hole. Otherwise, magnetic fields could be set up if different holes are used and therefore a loss of power, apart from the fact that it does not comply with the regs.
Have you ever looked into what sort of currents are needed to create a heating effect?
Is there any issue with fitting a metal back box in timber, as in recessed and surrounded by timber, not just screwed onto the outside?
Hi John, I just laughed (a plethora of mess) ha ha ha
Thank you
excellent video
Lazy council where I live did a cheap method by removing a single socket outlet and replacing it with a double socket plug outlet, my bedroom developed a problem within a few weeks with the left switch f*cking up and staying on.
A surprisingly interesting video!
I do have one question though... if you have a single socket and its fcu fitted to the same dual back box, how do you run the cable between them. There's typically no knockouts on the central divider so would you use the top (or bottom) knockouts to run a short length of cable? It's would be in a preferred zone so I'm guessing should be ok but I just wanted to check what best practice would suggest.
Answering my own question after coming back from Screwfix, in case anyone else was pondering what I was pondering! The central piece that divides dual back boxes into two is comprised of two parts - a facing strut that has screw holes into which you can screw faceplates, and a central 'wall' that physically divides the box into two. What I didn't realise is that although there are no knockouts in this central wall, it can be removed altogether whilst leaving the other piece in place. Which would seem sensible! 🤪
Love to know why they rust after 2 months or so?
Great video JP.
On a slight tangent; are there any regulations against passing through back boxes with cables from different circuits? for example if you have a light switch directly above a ring main socket, could you run the ring main cable down with the lighting cable through the light switch back box and continue down to the plug socket, to stay in the prescribed zone?
No, you may not do that.
522.6.202 A cable installed in a wall or partition at a depth of less than 50 mm from a surface of the wall or
partition shall:
(i) be installed in a zone within 150 mm from the top of the wall or partition or within 150 mm of an angle formed
by two adjoining walls or partitions. Where the cable is connected to a point, accessory or switchgear on any
surface of the wall or partition, the cable may be installed in a zone either horizontally or vertically, to the
point, accessory or switchgear. Where the location of the accessory, point or switchgear can be determined
from the reverse side, a zone formed on one side of a wall of 100 mm thickness or less or partition of
100 mm thickness or less extends to the reverse side, or
(ii) comply with Regulation 522.6.204
Note "Where the cable is CONNECTED TO...".
Not "passing through" - it has to be *connnected to* the accessory for the accessory to create a zone for it.
I have an ex council house I bought 30 years ago every light switch was the 16mm or the Imperial equivalent I think the reason they used these is because the plaster is the same thickness
I was hoping for an explanation of why metal back boxes are used instead of plastic in a solid wall.
"Oh look Marjorie, there are couple from number 42. Terrible wonky sockets they have. Such a shame."
Ha, maybe it's just me who says that, some people I know have a yellow double socket which is crooked in every plane in the middle of the wall in their new kitchen
Can you play the organ on another vid, I’d like to see that.
And take a look at that green radiator
@@darraghjoyce5663 Avocado! Oh the horror!
Have you ever heard of voltex switch sockets?
Volex - yes. Voltex - no.
In my house, which appears to have had a council rewire some time ago, 16mm backboxes are used for lightswitches. One of the issues though is that the rewire was done using the existing metal conduit in singles (including earth wires). This means I have ~40mm of depth from back of backbox to the plaster surface, which makes removing and refitting awkward (things don't quite lineup). Replacing these is also difficult as I've not seen single boxes with a centre knockout for cable entry, what would you do ?
20mm hole saw and cut your own centre hole. Drill new screw holes out in corners
I don't know if you have and equivalent in Britain but there are hole punches available in North America for punching larger holes in sheet metal, specifically for electrical boxes. A company called Greenlee makes sets of them, but they are not the only ones. There are two halves tightened together with a 1/4'' bolt, and as it is tightened it sheers a hole through the sheet metal. If you are putting a new box this may work, but not in an existing one already fastened into the wall as you need to access both sides to use it, so a bi-metal hole saw might be the answer there.
How come they are metric if you’re talking about UK?
Most things in the UK are metric and have been for decades.
@johnward I've come across a load of single back boxes with double face plates are they OK to ve like that or must i use a double with double or single with single
There are converter sockets which are doubles that fit over a single box, they are ok to use.
Otherwise no, as a normal double won't fit on a single box.
@@jwflame yeah that's what they are I wasn't sure never come across them before
How does that screwing in the metal conduit work when /both/ ends need to be screwed in? :)
On new installations start at one end and screw in one at a time. For a socket, the length of conduit to the socket is installed first, then the coupler is screwed on, then the brass bush is screwed into the coupler.
For the rare situation where two pieces of conduit need to be joined on an existing system between two existing items, the thread on one is cut extra long so a locknut and coupler can be screwed on completely, the two pieces are then installed and the coupler threaded back over the joint with the locknut securing it. The exposed thread then has to be painted to prevent corrosion.
Great video ty. In your opinion do you need to separately earth metal back boxes or is the connection through the screw onto the fixed lug sufficient. I have always tended to supplementary bond them to the face plate earth connection, but is this ott?
Connecting via one fixed lug is permitted, but like many things there is the choice between doing the absolute minimum required, or doing a decent job of it.
John Ward many thanks, agree totally. Really enjoy your videos, ty 😊😊
Who noticed the backbox pop into frame at about 0:10
Can anyone explain to me (complete novice) why after I disconnected a faulty transformer in my ceiling light some of my other lights don't work but some do - is it as simple as the order in which the cable goes to them? I presumed it would be all or none if it is a ring circuit... or perhaps that's the answer, they're on a separte loop off the main circuit?
You will need a spark to sort that job out mate
@@gravyboat2370 okey dokey, cheers 👍
Can anyone recommend a good book about backboxes?
Can you rethread 4ba ones 4mm?
probably, although you may need to drill the hole out first, as 4mm requires a slightly larger hole.
Can anyone tell me if they sell a triple plastic back box ( plasterboard ).
No, but if you really want a triple socket in plasterboard, you can get metal flanges to fit a metal box into plasterboard. MK part number 800ZIC.
Or just fit two double sockets.
Honestly , just use 35 for everything(or deeper) . why bother making your life harder ? Oh and top tip, if your trying to line up 2 sockets just use conduit between them , it will lock them in place level :)
Brass bushes in 20mm holes, 14.30, did you see how poorly and loose fitting the hex nut end was. I remember back in the early 80's before metric brass was used how the hex nut end used to cover the actual hole. Nowadays you have to put a 20mm lock ring under the hex end to stop it popping thru' the hole. Brass bushes are terrible quality now
I've always called them pattress boxes...
I call the metal onesback boxes and the platerboard ones patresses.
Surface plastic mounted boxes are called patress' metal are back boxes.
@@muzikman2008
Spot on.
Let’s have a closer look at a back box 😂😂😂😂😂😂😂😂
Hello John. Can I have your e mail please? I ve got couple questions. Cheers
On the channel About page, or at flameport.com
Thank you. Just sent you an email. Cheers
OK the more video's you do on UK standards the more it lookes like the UK has had 0 evolution for the past 40 years!
not only are those boxes metal but you can't even fit them together in any sensible way!
Not sure what you mean. Metal boxes are strong and fire proof so advantageous. We do fit surface mounted plastic boxes, or plastic cavity boxes. Metal boxes aren't an issue as long as they are grounded.
Trust me... there has certainly been many changes over forty years. Our IEE regulations are VERY stringent.
Plastic boxes are available, but galvanised steel is more fire resistant. As for fitting them together, there's really not much point as sockets/outlets and switches tend to come in standard sizes, and overwelmingly single and doubles with a very few triples. I'm leaving out special purpose ones like outlets for electric cookers and so on.
@@TheEulerID
There's actually quite a few fused triples around now, have a couple in my house.
what's your deal with fire ?
are your house made from matchstick?
A sensibly maintaine electric istalation dose not catch fire ever in the first place!
Also I would be so shure metal boxes are more fire-resistant than plastic.
Finally when I say mont them together I mean that if I go to any modern electric supplier I will be able to get enlessly clipable box therfore creating the disiered shape with out any problems
@@martinw245 I'm sorry but the fact you still use rings and have the most mainquiest plug in existence ( that things might be safe but it's also a pain in the ass to do anything with it) makes me encline to say that you haven't evolved that much.
seriously what is wrong with the europlug?????