I always leave a neat edge on my Strips. It looks better to start with but it also helps a lot if you need to replace a unit. Its a good working practice. The cables go back in much easier, which is helpful when there are a few cables coming in one point such as the spur point of a ring circuit. I rant, curse and rave when I'm replacing a consumer unit and the bell end before me left a big pile of ragged edges for me to battle with. Pride in ones work people, pride in ones work.
How do ragged edges make it more difficult? Certainly don't have long "peels" hanging off - that's unsightly to say the least! - and while it definitely DOES look more aesthetically pleasing with a neat cut , it's also very easy to nick the actual wires. It may look neat, but if it's nicked the connection/wiring is compromised.
With me, depends on the terminal/wire combination. Single conductors in terminals designed for 2 (2.5s in sockets, 1mm2 in light switches, yes. 1.5 in light switches: depends on the design. Otherwise usually no. Now to open it up further... ferrules on flex? :D
The practice of using cross-sectional area (metric) is sensible. In the US we use AWG (American Wire Guage) where a larger number means a smaller wire, up to 0000 (4/0 or Four-aught). After that we use an area measure - units are MCM (Thousand Circular Mils) where a Mil is 0.001".
I have had a couple of rolls that was covered with talc incorrectly, absolute nightmare indeed. Thankfully it's been a few years since i came across the problem.
Sleeve I tend to use a piece of earth wire and strip the sleeve, so as not to need a easy to lose sleeve roll, plus I tend to have extra short offcuts in any case. Here in SA you need to use a cable gland into a box, irrespective of whether it is a flush mount or surface box, so no grommets. The trunking I buy and put self adhesive tape on separately, as it is not common to get a self adhesive one. Saves a lot of time, plus no sagging ever, especially after 2 paint coats seal it in. A single screwnail every so often helps, especially with the larger sizes where you might run 10 or more inside the trunk. Stick, then drill through and place the screwnail in then gently tap into position. Those clips can be a pain at times, especially if you have a wall seemingly made out of powder which does not hold, or those walls seemingly harder than granite. Easyhold and cable tie to the rescue, but not as nice looking, but great for a bundle in a roof to make it neat along a wall.
TheChipmunk2008 i managed to stretch couple of earth conductors by pulling throughout the cast copex in concrete, i used metal draw wire and i applied my body force to pull them out from the socket, but that happens only if you attach the earth conduit to the metal draw wire and only for distances like 3-5 meters long, you can spot that the earth wire is longer and thinner but not broken and the 1.6 formula for inspection and testing would fail
It's not a myth, it stretches the CPC. If you strip a large amount of twin+earth in a board then notice how much longer the CPC is after you size up the rest of the conductors. You have to be skilled and experienced enough to know when you've damaged it too much.
It will yield/stretch when pulled as the yield strength of copper is 70Mpa or 70N/mm2. If it is 1.5mm^2 CPC that is force of 105N or 10.7 kg. This is much force than needed to tear the cable sheaf so the earth is deforming and stretching. As this will therefore decrease the cross sectional area it should not be done.
@@NebakinezaOG I'm not convinced personally, not saying the copper conductor can't be stretched but i doubt the force used while pulling the CPC to strip a PVC cable could stretch a solid copper core. Whats most likely happening with the CPC being longer is you are pulling the CPC while holding the other cores so it is shifting within the PVC insulation and pulling towards you while the other two cores are not moving.
@@stevoc9930 try it on a fresh drum, there’s no way it would slide within the sheath. Strip a good amount by yanking the CPC through and then straighten out all the cores. You’ll see the CPC will be several inches longer
Here in the US, this type of cable is typically referred to as Romex, named after one of the major brands of it. Ours has a thin brown paper covering the individual wires inside instead of having talc coating. Interesting that cable that is much the same is used in the UK, though. We also don't have any covering or anything over the earth wire. I do like the idea of having that sleeving though; in a cramped electrical box we have to be somewhat careful to make sure that earth doesn't short out to the live connection on a switch or receptacle, which could be pretty dangerous.
I thought I would mention that our screw terminals in the US are open! and we also have outdoor/buried rated cabling which is closer, however it seals in the ground conductor in the molding process of the cable sheath.
Thank you JW for another informative video. I take it you are a licensed electrician (I know next to nothing about electrical things but am very curious.) I very much appreciate your attention to detail and soothing voice which is easy on the ears.
Would have been great to end this good video with the different ways to terminate and the ways not to terminate. e.g twisting wires together, bending the end to create loop etc
Bending back of the stripped end is sometimes necessary because the single screw barrel terminals are used in the UK. Provides a better contact especially if a single cable is being connected. Clamping pan head screws with square washers or terminals similar to that used on circuit breakers are probably used elsewhere. If the terminal is just the pan head screw a C loop must be formed on the wire so that it can be placed under the screw head.
Can someone explain to me how mice seem to be immune to 240v AC? They will happily chew away the insulation on all three cores, but never have i found the culprit laying dead at the scene of the crime. The little blighter's seem to get away with it everytime.
Double insulated rodents, they don't always get away, love watching the possums run up to the 22Kv at my customers farm, BOOM. I think thats what Freddy Mercury was singing about all those years ago. Thats real voltage drop, they get to the voltage and drop.
Fixings, such as the clip shown in the video, in escape routes now have to be fire-proof, in practice metal. That means metal clips for surface mounted cables or metal conduit. Most dwelling this is going to mean corridors, stairs and upper storey landings. Regulation 521.11.201 came into force 1 July 2015. electrical.theiet.org/wiring-matters/issues/58/fire-performance-of-cable-supports/
This is a good video - thanks, but I would like to make some comments. (1) Use of a stanley knife to cut the outer sheath is impractical: it would seem from this that you haven’t carried out much installation work. In a flush box or a c.u. getting the blade round the rear end of the sheath would be mightily awkward and the risk of damaging the conductor insulation would be unaceptably high! (2) You say that metal buckle clips are outdated, but the latest wiring regs require the use of them to preclude cables collapsing in a fire. (3) If a single 2.5sq mm cable is to connect to a s/o, cu,or other termination, the conductors should be doubled back to ensure a good connection. Personally, I dislike 2.5 T&E: in ring final circuits, it’s pretty much impossible to ensure continuity, as twisting the cores does not provide a secure joint, and placing the conductors side by side means continuity is dependent on the security of the screws clamping the conductors in each s/o or “spur unit”. 4mm sq is a better option, in a radial configuration, which has the advantage that ring circuit continuity testing is not required on EICR inspections. For use outside the equipotential zone, T&E in plastic trunking is unacceptable in my view. Pvc/swa/pvc or micc is far safer.
4mm t&e is quite pricey and in practice you would find it difficult to spur off of. You wouldn't be able to put it on a 32amp mcb/rcbo unless it was directly clipped to the the wall. or you down rate to a 20 amp beeaker. In conduit or trunking 4mm t&e is de-aerated to 30amps. 2.5mm t&e is absolutely fine in a domestic environment. radials over rings unless it's high load circuits like kitchens. As it's much easier to trace faults and unless it's a missing cpc they usually don't function.
I was always under the impression That the central earth was left bare so that if the live or neutral was damaged, there was a good chance it would short with the earth, tripping the RCD rather than shorting with each other and potentially causing a fire.
Yep, me too. But I have yet to find anything that hints of official decision to make it so. So perhaps that is just a 'story' and the real reason is cost staving; which I would find disappointing.
This cable is pretty well identical to what we have in Canada, "Non Metallic Sheathed" cable, sometimes called "Romex". Installation methods differ here as to use of, installation , fastening, and sleeving of the bare conductor .. (we don't!)
+REWYRED The requirement to sleeve the bare earth came in here in the UK sometime in the late 60s, before then it was left bare. It was plain green to begin with but in the late '70s it was changed to yellow and green.
snip end open with side cutters grab earth with pliers pull back to required length then ether score and peel or snip outer off using knife risks snagging insulation on conductors
I've seen twin and earth used for extension reels. All home made and wrapped around a short piece of fence wood. The damage to the thing was mad and the people using it were.. mad! Nice vid. More please!
Another well informed video. I will be paying extra attention when a sparky does any work now and know if they are a electrician or a cowboy electrician.
To me as a Swede, having any wires not insulated just looks.... wrong! Where is the single fault protection? Of course, the PE won't carry any current unless there already is a problem somewhere, but.. no lol
@@BPo75 If there is a failure of the insulation in the cable itself, with a neutral to CPE fault, then it will pop the RCD protection (any such insulation breakdown tends to be gradual, although if it's an older installation without RCD protection, then it will be the MCB/fuse that will fail on a line/CPE short, although It's really no different to what would happen if the insulation is breaking down in a cable with insulation on the CPE. It's just going to take a bit longer to find out. In practice, it seems to be extremely rare unless the cable is damage by, for instance, a screw being driven through it.
@ John ward, do you think you could do a video on MICC cable possibly. Your videos are always very informative and lots of the trainees on Electriciansforum.co.uk have mentioned how useful they have found your channel. Thanks. :)
where twin & earth is run on a bare brick or block wall capping should be used to protect the cable from the plasterers trail that's the reason for capping.
Hi John, Love the vids.. Anyway, save time stripping that type of cable. No need to slit it. Just score deep around it, bend it slightly to see if when it actually cuts through the sheath- on both sides. Then grab both sides of the cable with each hand and pull. It'll generally snap and the sheath after the cut will just slide off.
Hi John, another really good video, thankyou. I would love to see a video explaining the relationships/differences between MCB's, thermal overloads and motor circuit breakers. Alex.
+John Ward I tend to loop back the earth wire by doubling it, then poking it into the correct length of sleeving for if it wasn't doubled... thus leaving it completely insulated but present
I've encountered too many cut earths, even on socket outlets. Call me racist, but often in premises owned by foreign types, where I guess they just don't bother with earths in their home countries.
+Green Silver You can find special voltage sense probe which can detect the wires. Like this one www.amazon.com/Fluke-1AC-A1-II-VoltAlert-Non-Contact-Voltage/dp/B000EJ332O/ref=sr_1_1?s=hi&ie=UTF8&qid=1460328074&sr=1-1&keywords=fluke+power+pen
+Green Silver Building regulations state where cables can be run within walls, if the contractor that wired your house followed these regulations you can take an educated guess at where the wires will be run but if in doubt use something like +MegaGreenman28 suggested. As a general rule of thumb do not drill the wall directly above a plug socket or adjacent to it in a vertical or horizontal plane so most wires will be directly up and into the ceiling or make a loop around the room connecting sockets (ring main?) There are also similar guidelines for Gas and Water piping but these are easier to avoid.
+Matt Warrillow Edit, i retract my comment about using the tools recommended by +MegaGreenman28 as this may not detect live cabling behind plaster/plasterboard walls, you will be better off using a stud finder that also detects live AC. www.amazon.com/Zircon-MultiScanner-i520-Center-Finding-Electrical/dp/B000TD1JCQ/ref=sr_1_2?s=hi&ie=UTF8&qid=1460390944&sr=1-2&keywords=electric+and+stud+finder
Little observation.... Placing two cables through different holes in a metal enclosure....was mentioned in a previous video of yours, using meter tails and with regard to magnetic fields being created. It is odd that the powers that be (BS7671) do not recommend this in a consumer unit yet allow it with cables in back boxes.
+ningis21 You shouldn't put the neutral and phase(s) through different holes in a metal enclosure. That what that other video was about. These are are cables that contains both the neutral and a phase, so the they should normaly cancel out., so you don't get any eddy currents. In some cases you might get small
+ningis21 Only will be an issue if you place the line and neutral from the same cable through different holes. This then makes a transformer with the metal box between being the shorted secondary. However much current is flowing in the cable is then flowing in the steel, and heating it up. 20A from a ring main or spur will not do much heating, but in the consumer unit where you can have 60A flowing this then causes a lot of heating. The separate holes here are for separate cables, there will be no circulating current unless you have a broken ring, and even there the intact conductor will tend to balance the current flow so there will be minimum heating.
But the difference here is you're typically going to be running paired Line+Neutrals through, so I believe the EM field should be cancelled out. Single-core tails are a different matter.
Probably. There isn't any one cable to use, it depends on the total load, circuit length and other factors. However 1.5mm² T&E is suitable for most normal installations.
1mm T&E is usually more then adequate. it's easily terminated and much easier to work with. Most recessed lighting is led or low power consumption these days. Unless you are doing a vast amount on a singular circuit 1mm is usually fine. If in doubt consult a qualified electrician. 😉
No. Just use a bonding coat over the capping and leave 3mm shy of the surface. Then use any powdered filler you like but I recommend Gyproc easifill as it's easy to sand. You could use bonding to fix oval conduit either. Then fill as above.
Just a sort-of "in your experience" question, and I realise the answer by some may not agree with others. With regards to scoring the outer jacket, is a sharp blade better or a not-so sharp one? If it's very sharp, a cleaner cut but also easy to nick the wires inside. If it's not-so sharp, not as clean, but less risk of wire damage I would think.
As sharp as possible, scoring then only requires very light pressure and is easily controlled. Blunt knives are useless as the amount of pressure required to score depends on how worn the blade is, and having to apply extra force means it's more likely to slip and cut things you do not want to cut.
John im fitting a cctv camera to the outside of my property. It comes with its own junction box twin and earth connection. Im using standard 1mm cable as its a standard camera low wattage. Immdrilling through from the outside wall into a bedroom. Is it better to use a stiffer cable or flex for that job or doesnt it make a difference
In North America, the active wire is black and the neutral is white. If there are 2 active wires, one is black and the other is red. The earth(ground) is bare with no sleeve.
I've found plasters using plastic floats. This should stop the cable bing damaged. Might even save the plasterers getting arrested should police get into their tool bags !
Another method of stripping the cable I was shown whilst at college was at top of the cable by using a knife and strip down towards the bare earth without trying to cut through the insulation of the wire. I did it initially lol but mastered it in the end
I like the pliers which grips & then strips in one operation... a single-handed job... 😎 U didnt mention the risk of nicking the copper whilst stripping it, thereby leaving a stress-point where the copper can fracture & break away.... seen this many times...😞
Hello John Great Video...........I watched nearly all of your videos But can you advise what best way of joining inline a 10mm cable ie, connector strips etc? Your opinion on this is greatly appreciated. Thanks
Hi John, if this cable was plastered into a wall, it would mean destroying the house to rewire in 40 - 60 years time. Leads me on to a general question, during rewiring does it mean ripping up floor boards and digging through plaster or is the old wiring abandoned and horrible plastic trunking installed all over the house?
Rewiring can be done with surface trunking, but that's normally only used when it has to be done as quickly and cheaply as possible. If the old wiring is in concealed conduit then that could be reused, but if not, or if things are needed in new locations then concealed wiring does mean chasing out walls, lifting floorboards and so on.
Thoughts; I'll use a stanley where convenient if I want a particularly nice finish. Not convenient for C.U. wiring for the most part, where I use the snip-into-the-end-and-pull-the-earth method, then snip the outer with the snips, not stanley, as there's too much risk of slicing into another wire in tight spaces (not advised when working live = often), alongside the distinct possibility of sliced fingers. Also seen too many instances of careless stanley work resulting in exposed live conductors, including some pretty nasty faults in damp environments (blown SWAs at the gland). As a rule, when I use a stanley, if I cut too deep then I cut the length off and start again (assumes you have length to spare in the first place). Score the outer only... Stripping the inners - My 1.5/2.5/+ strippers of choice are my quite old but still awesome Kew Technik snips that snipped through a live 1.5 T+E many years ago ("power off mate?" - "yeah" - *snip, bang* - "nope..."). Amusingly it blew two small holes of different sizes in the blades - one being great for 0.75-1.5mm, other being perfect for 2.5. I always try to double-over exposed conductor ends where the terminal they're being fixed into allows for it (particularly if only hosting a single conductor), especially the thinner earth. I see this as creating a better contact (lower resistance) due to increased contact area, allows for higher clamping force, reduces localised heating at the connection, and increased resistance to breaking the core in the terminal where an over-tightened screw may otherwise crush the copper. T+E cable = for fixed installations only. Don't do as some do and stick plugs on the end of it to be used as a substitute for flex cable... I prefer to use capping if I C.B.A. purely to allow for the possibility of pulling in/out cables at a later date if required (better than having to chop back into that newly plastered/decorated wall...). If I'm dealing with metal back boxes I tend to add a 1.5/2.5 G/Y length of 'singles' wire from it to the socket/switch/etc. where appropriate. Better that have a back-box potentially go live if/when the plate is pulled away sometime. Thanks for taking your time to do these videos, JW. Always informative, and food for thought.
+9ff70f96 Majority of the time i use the snip-into-the-end-and-pull-the-earth method, then snip the outer with the snips as it saves sooo much time and as its always said, TIME IS MONEY!! CK, NWS and a few other brands make snips that have built in 'strippers' for 1.0/1.5 and 2.5mm 2 cable, very handy in tight spaces! Only down side is when you need to cut a bigger cable ie 6mm up, you need to make 2-3 passes as you don't have a full length blade. As for earthing back boxes, I tend to leave an extra 4-6 inches of T+E on cables in back boxes during 1st fix so that during 2nd fix, you snip off the extra cable, remove ONLY the CPC and terminate in the back box with a piece of earth sleeving then to the faceplate weather it be socket, switch, cooker isolator etc.
Sorry if I missed it but what do you think about folding over the ends? I always did it, but on ring circuits to sockets now I'm wondering if it makes a cleaner, more certain/secure connection without, especially when replacing sockets in tight spaces. "Theoretically" a doubled/folded over end could snap under the terminal or when pushing the socket into place.
Depends on the size of the wires relative to the size of the the terminals. With multiple wires it may not be necessary or even possible to fold the ends, but certainly recommended with only a single wire and a relatively large terminal.
@@jwflame Thank you, that's more or less what I thought. I wonder if someone will try inventing a socket which takes wires with a Wago style snap terminal.
I have never seen that green/yellow sleeving before and I can't seem to find it even now. It seems like a handy way to reduce the chance of accidental shorts. Is there another name for it? It is a UK only item?
It's just called PVC sleeving, this is a random example: www.cef.co.uk/catalogue/products/213784-3-0mm-green-yellow-sleeving-100m-reel It's only common in the UK because of the type of wiring - the flat cable doesn't have any insulation over the earth conductor. Other countries use cables with the earth conductor already insulated in green/yellow, so there would be no need to use separate sleeking there.
@@jwflame All the home electrical wire I've seen or worked with in the US has a bare earth conductor. As far as I have seen, they are always just left bare in the box. I'm not sure why we (Americans) didn't get the memo on this. Maybe because our voltage is lower? I can't seem to find that material anywhere and I've never heard of anyone sleeving before watching this video.
Round ones can be obtained but are seldom used, most building wiring is either the flat T&E as shown in the video, or single insulated wires inside metal or plastic conduit.
greetings, in Australia they used to the solid core cable, that changed years ago to multi strand, including the earth wire insulated. Do you see any advantages in solid or multi strand, what are your thoughts on both.
We have NEVER ever had a non stranded earth conductor in Oz, bare yes, solid never, solid cable was only ever used by cheap arse shit contractors because it was around half a beer cheaper than stranded cable per drum to purchase, the earth has always been stranded originally three strands now minimum of seven, the earth is the most importaint conductor in the circuit. On a side note, thats why earth pins are the longest pins in plugs, and why the earth pin is the bottom pin in Aussie sockets, so if the plug is hanging out of the socket the earth disconects last.
Yes ,well my house in Australia is all solid core cable, not stranded at all.....I have lots of friends who I have checked there house and it's all solid core cable.....this is in Brisbane.......what are your thoughts on solid verses stranded cable, what do you think is best....thanks....
Either cut a 45 degree angle in each end (making sure you cut the angle the right way), or just butt one piece up to the other at 90 degrees leaving the ends square (my preferred method), and trim with snips to allow the wire/cable to pass through the bend. Or you could go the quicker but rougher and more expensive route by buying 90 degree caps of the appropriate type (internal/external/etc bends) to cover-up gaps in your cuts (finished job tends to look worse, in my opinion).
Also when removing insulation try not to cut in to the conductor as this could reduce the csa of the conductor and may introduce a fatigue area (where if it bent too much it could fracture on the cut area)
That's a can of worms. Some people claim that you don't need to if there's a solid lug (that's per the regs, I believe.) but to me it's simply unprofessional not to. Because the guy who mentored me when training me [mumble] years ago... would've torn me a new one if I left out the earth flylead!
I moved into a newly built house in 1999. About 5 years after moving in one of our kitchen sockets started playing up - one of the switches gone u/s. On fitting the replacement socket - discovered that no earth lead fitted to the metal box earthing terminal-I rectified that. Being a curious chappie I went round the whole house to check all other sockets- none of the back boxes had the earth lead fitted - they do now! Still my house - my responsibility.
The sockets are designed with metal collars connected to the earth on the socket connector. In principle, when you tighten the fixing screws up, they will also earth the box too. However, for some that's not enough.
@@TheEulerID JW has a video of a BS socket outlet where the ground strap does not extend to the fixing holes and so would not be made to the back box. Better to make a real connection to the box in all cases. ruclips.net/video/kPpX1YXvGcg/видео.html
i managed to stretch couple of earth conductors by pulling throughout the cast copex in concrete, i used metal draw wire and i applied my body force to pull them out from the socket, but that happens only if you attach the earth conduit to the metal draw wire and only for distances like 3-5 meters long, you can spot that the earth wire is longer and thinner but not broken and the 1.6 formula for testing would fail by a small margin
I do love the very formal, proper british tone combined with a family guy t shirt.
I always leave a neat edge on my Strips. It looks better to start with but it also helps a lot if you need to replace a unit. Its a good working practice. The cables go back in much easier, which is helpful when there are a few cables coming in one point such as the spur point of a ring circuit. I rant, curse and rave when I'm replacing a consumer unit and the bell end before me left a big pile of ragged edges for me to battle with. Pride in ones work people, pride in ones work.
Damn you! I used to bend the sheath and chop as shown. Now, because of your comment, I have to slit round and leave a neat end!
How do ragged edges make it more difficult? Certainly don't have long "peels" hanging off - that's unsightly to say the least! - and while it definitely DOES look more aesthetically pleasing with a neat cut , it's also very easy to nick the actual wires. It may look neat, but if it's nicked the connection/wiring is compromised.
Interesting... Now, who doubles over the conductor when terminating?
With me, depends on the terminal/wire combination. Single conductors in terminals designed for 2 (2.5s in sockets, 1mm2 in light switches, yes. 1.5 in light switches: depends on the design. Otherwise usually no.
Now to open it up further... ferrules on flex? :D
@@guineafowl8029 That is how it should be done if there is room inside the terminal to do so.
The practice of using cross-sectional area (metric) is sensible. In the US we use AWG (American Wire Guage) where a larger number means a smaller wire, up to 0000 (4/0 or Four-aught). After that we use an area measure - units are MCM (Thousand Circular Mils) where a Mil is 0.001".
Yeah its you guys and Myanmar and Liberia
A nice little unique club
I have had a couple of rolls that was covered with talc incorrectly, absolute nightmare indeed. Thankfully it's been a few years since i came across the problem.
Sleeve I tend to use a piece of earth wire and strip the sleeve, so as not to need a easy to lose sleeve roll, plus I tend to have extra short offcuts in any case. Here in SA you need to use a cable gland into a box, irrespective of whether it is a flush mount or surface box, so no grommets.
The trunking I buy and put self adhesive tape on separately, as it is not common to get a self adhesive one. Saves a lot of time, plus no sagging ever, especially after 2 paint coats seal it in. A single screwnail every so often helps, especially with the larger sizes where you might run 10 or more inside the trunk. Stick, then drill through and place the screwnail in then gently tap into position.
Those clips can be a pain at times, especially if you have a wall seemingly made out of powder which does not hold, or those walls seemingly harder than granite. Easyhold and cable tie to the rescue, but not as nice looking, but great for a bundle in a roof to make it neat along a wall.
Thank you for destroying the stupid myth about damaging the earth by pulling on it!
TheChipmunk2008 i managed to stretch couple of earth conductors by pulling throughout the cast copex in concrete, i used metal draw wire and i applied my body force to pull them out from the socket, but that happens only if you attach the earth conduit to the metal draw wire and only for distances like 3-5 meters long, you can spot that the earth wire is longer and thinner but not broken and the 1.6 formula for inspection and testing would fail
It's not a myth, it stretches the CPC. If you strip a large amount of twin+earth in a board then notice how much longer the CPC is after you size up the rest of the conductors. You have to be skilled and experienced enough to know when you've damaged it too much.
It will yield/stretch when pulled as the yield strength of copper is 70Mpa or 70N/mm2. If it is 1.5mm^2 CPC that is force of 105N or 10.7 kg. This is much force than needed to tear the cable sheaf so the earth is deforming and stretching. As this will therefore decrease the cross sectional area it should not be done.
@@NebakinezaOG I'm not convinced personally, not saying the copper conductor can't be stretched but i doubt the force used while pulling the CPC to strip a PVC cable could stretch a solid copper core. Whats most likely happening with the CPC being longer is you are pulling the CPC while holding the other cores so it is shifting within the PVC insulation and pulling towards you while the other two cores are not moving.
@@stevoc9930 try it on a fresh drum, there’s no way it would slide within the sheath. Strip a good amount by yanking the CPC through and then straighten out all the cores. You’ll see the CPC will be several inches longer
Here in the US, this type of cable is typically referred to as Romex, named after one of the major brands of it. Ours has a thin brown paper covering the individual wires inside instead of having talc coating. Interesting that cable that is much the same is used in the UK, though.
We also don't have any covering or anything over the earth wire. I do like the idea of having that sleeving though; in a cramped electrical box we have to be somewhat careful to make sure that earth doesn't short out to the live connection on a switch or receptacle, which could be pretty dangerous.
I thought I would mention that our screw terminals in the US are open!
and we also have outdoor/buried rated cabling which is closer, however it seals in the ground conductor in the molding process of the cable sheath.
Go back to some old UK installations, and I can guarantee that many of those won't have earth sleeving on either.
I did always wonder what the white powdery stuff inside was, and now I know. :)
Good ole JW. Basic bog standard electrician info. Why is it that so many can't even get this stuff right?
Thank you JW for another informative video. I take it you are a licensed electrician (I know next to nothing about electrical things but am very curious.) I very much appreciate your attention to detail and soothing voice which is easy on the ears.
Would have been great to end this good video with the different ways to terminate and the ways not to terminate. e.g twisting wires together, bending the end to create loop etc
Bending back of the stripped end is sometimes necessary because the single screw barrel terminals are used in the UK. Provides a better contact especially if a single cable is being connected. Clamping pan head screws with square washers or terminals similar to that used on circuit breakers are probably used elsewhere. If the terminal is just the pan head screw a C loop must be formed on the wire so that it can be placed under the screw head.
Can someone explain to me how mice seem to be immune to 240v AC? They will happily chew away the insulation on all three cores, but never have i found the culprit laying dead at the scene of the crime. The little blighter's seem to get away with it everytime.
+100SteveB Until their pee completes a circuit to earth.
CATIII insulated legs; an evolutionary adaptation.
Double insulated rodents, they don't always get away, love watching the possums run up to the 22Kv at my customers farm, BOOM. I think thats what Freddy Mercury was singing about all those years ago.
Thats real voltage drop, they get to the voltage and drop.
Fixings, such as the clip shown in the video, in escape routes now have to be fire-proof, in practice metal. That means metal clips for surface mounted cables or metal conduit. Most dwelling this is going to mean corridors, stairs and upper storey landings. Regulation 521.11.201 came into force 1 July 2015.
electrical.theiet.org/wiring-matters/issues/58/fire-performance-of-cable-supports/
This is a good video - thanks, but I would like to make some comments. (1) Use of a stanley knife to cut the outer sheath is impractical: it would seem from this that you haven’t carried out much installation work. In a flush box or a c.u. getting the blade round the rear end of the sheath would be mightily awkward and the risk of damaging the conductor insulation would be unaceptably high! (2) You say that metal buckle clips are outdated, but the latest wiring regs require the use of them to preclude cables collapsing in a fire. (3) If a single 2.5sq mm cable is to connect to a s/o, cu,or other termination, the conductors should be doubled back to ensure a good connection. Personally, I dislike 2.5 T&E: in ring final circuits, it’s pretty much impossible to ensure continuity, as twisting the cores does not provide a secure joint, and placing the conductors side by side means continuity is dependent on the security of the screws clamping the conductors in each s/o or “spur unit”. 4mm sq is a better option, in a radial configuration, which has the advantage that ring circuit continuity testing is not required on EICR inspections. For use outside the equipotential zone, T&E in plastic trunking is unacceptable in my view. Pvc/swa/pvc or micc is far safer.
4mm t&e is quite pricey and in practice you would find it difficult to spur off of. You wouldn't be able to put it on a 32amp mcb/rcbo unless it was directly clipped to the the wall. or you down rate to a 20 amp beeaker. In conduit or trunking 4mm t&e is de-aerated to 30amps. 2.5mm t&e is absolutely fine in a domestic environment. radials over rings unless it's high load circuits like kitchens. As it's much easier to trace faults and unless it's a missing cpc they usually don't function.
I was always under the impression That the central earth was left bare so that if the live or neutral was damaged, there was a good chance it would short with the earth, tripping the RCD rather than shorting with each other and potentially causing a fire.
+SLRist It wouldn't cause a fire, would it? as the MCB would trip off at the required breaking current or short circuit capacity?
+Birdiemango1 I guess it depends what kind of combustible materials were nearby at the time the cable was damaged. I did say potentially.
Yep, me too. But I have yet to find anything that hints of official decision to make it so. So perhaps that is just a 'story' and the real reason is cost staving; which I would find disappointing.
Great vid, really helped me with my practical work on my course.
This cable is pretty well identical to what we have in Canada, "Non Metallic Sheathed" cable, sometimes called "Romex". Installation methods differ here as to use of, installation , fastening, and sleeving of the bare conductor .. (we don't!)
+REWYRED The requirement to sleeve the bare earth came in here in the UK sometime in the late 60s, before then it was left bare. It was plain green to begin with but in the late '70s it was changed to yellow and green.
snip end open with side cutters grab earth with pliers pull back to required length then ether score and peel or snip outer off using knife risks snagging insulation on conductors
I've seen twin and earth used for extension reels. All home made and wrapped around a short piece of fence wood. The damage to the thing was mad and the people using it were.. mad!
Nice vid. More please!
Another well informed video. I will be paying extra attention when a sparky does any work now and know if they are a electrician or a cowboy electrician.
Leaving the earth wire bare within the cable, not only makes it a bit cheaper but also a bit thinner too. It may be marginal, but every little helps.
To me as a Swede, having any wires not insulated just looks.... wrong!
Where is the single fault protection?
Of course, the PE won't carry any current unless there already is a problem somewhere, but.. no lol
@@BPo75 If there is a failure of the insulation in the cable itself, with a neutral to CPE fault, then it will pop the RCD protection (any such insulation breakdown tends to be gradual, although if it's an older installation without RCD protection, then it will be the MCB/fuse that will fail on a line/CPE short, although
It's really no different to what would happen if the insulation is breaking down in a cable with insulation on the CPE. It's just going to take a bit longer to find out.
In practice, it seems to be extremely rare unless the cable is damage by, for instance, a screw being driven through it.
@ John ward, do you think you could do a video on MICC cable possibly. Your videos are always very informative and lots of the trainees on Electriciansforum.co.uk have mentioned how useful they have found your channel. Thanks. :)
Such excellent videos for someone starting out. Thank you
where twin & earth is run on a bare brick or block wall capping should be used to protect the cable from the plasterers trail that's the reason for capping.
Hi John, Love the vids.. Anyway, save time stripping that type of cable. No need to slit it. Just score deep around it, bend it slightly to see if when it actually cuts through the sheath- on both sides. Then grab both sides of the cable with each hand and pull. It'll generally snap and the sheath after the cut will just slide off.
Hi John, another really good video, thankyou. I would love to see a video explaining the relationships/differences between MCB's, thermal overloads and motor circuit breakers. Alex.
Good recommendation with not cutting off the earth at the end of the video..
+Colin Richardson The plastic boxes should have a place to slot it in so people are less likely to be a prat .
+Andrew Joy Some plastic boxes do have a terminal, but plenty do not.
+John Ward I tend to loop back the earth wire by doubling it, then poking it into the correct length of sleeving for if it wasn't doubled... thus leaving it completely insulated but present
I've encountered too many cut earths, even on socket outlets. Call me racist, but often in premises owned by foreign types, where I guess they just don't bother with earths in their home countries.
9ff70f96 Even more reason why everyone should follow the vastly superior UK electrical standard
What do you recommend for finding wiring that's been plastered over, I mean when I put up shelves, I don't want to screw into anything bad.
+Green Silver You can find special voltage sense probe which can detect the wires.
Like this one www.amazon.com/Fluke-1AC-A1-II-VoltAlert-Non-Contact-Voltage/dp/B000EJ332O/ref=sr_1_1?s=hi&ie=UTF8&qid=1460328074&sr=1-1&keywords=fluke+power+pen
+Green Silver Building regulations state where cables can be run within walls, if the contractor that wired your house followed these regulations you can take an educated guess at where the wires will be run but if in doubt use something like +MegaGreenman28 suggested.
As a general rule of thumb do not drill the wall directly above a plug socket or adjacent to it in a vertical or horizontal plane so most wires will be directly up and into the ceiling or make a loop around the room connecting sockets (ring main?)
There are also similar guidelines for Gas and Water piping but these are easier to avoid.
+Matt Warrillow Edit, i retract my comment about using the tools recommended by +MegaGreenman28 as this may not detect live cabling behind plaster/plasterboard walls, you will be better off using a stud finder that also detects live AC.
www.amazon.com/Zircon-MultiScanner-i520-Center-Finding-Electrical/dp/B000TD1JCQ/ref=sr_1_2?s=hi&ie=UTF8&qid=1460390944&sr=1-2&keywords=electric+and+stud+finder
Little observation.... Placing two cables through different holes in a metal enclosure....was mentioned in a previous video of yours, using meter tails and with regard to magnetic fields being created. It is odd that the powers that be (BS7671) do not recommend this in a consumer unit yet allow it with cables in back boxes.
+ningis21 You shouldn't put the neutral and phase(s) through different holes in a metal enclosure. That what that other video was about.
These are are cables that contains both the neutral and a phase, so the they should normaly cancel out., so you don't get any eddy currents.
In some cases you might get small
+ningis21 Only will be an issue if you place the line and neutral from the same cable through different holes. This then makes a transformer with the metal box between being the shorted secondary. However much current is flowing in the cable is then flowing in the steel, and heating it up. 20A from a ring main or spur will not do much heating, but in the consumer unit where you can have 60A flowing this then causes a lot of heating. The separate holes here are for separate cables, there will be no circulating current unless you have a broken ring, and even there the intact conductor will tend to balance the current flow so there will be minimum heating.
But the difference here is you're typically going to be running paired Line+Neutrals through, so I believe the EM field should be cancelled out. Single-core tails are a different matter.
Which cable do you need to install recess spots?? I’ve used twin and earth (3 core) 1.5 square mm white cable .. is that right??
Probably. There isn't any one cable to use, it depends on the total load, circuit length and other factors. However 1.5mm² T&E is suitable for most normal installations.
1mm T&E is usually more then adequate. it's easily terminated and much easier to work with. Most recessed lighting is led or low power consumption these days. Unless you are doing a vast amount on a singular circuit 1mm is usually fine. If in doubt consult a qualified electrician. 😉
Would it be safe to do the following:
Install cables into wall
Cover with steel channel
Fill in the hole with expanding foam
?
Thanks
Mr J if you have to ask, you’re probably better off calling a professional.
No. Just use a bonding coat over the capping and leave 3mm shy of the surface. Then use any powdered filler you like but I recommend Gyproc easifill as it's easy to sand. You could use bonding to fix oval conduit either. Then fill as above.
Just a sort-of "in your experience" question, and I realise the answer by some may not agree with others. With regards to scoring the outer jacket, is a sharp blade better or a not-so sharp one? If it's very sharp, a cleaner cut but also easy to nick the wires inside. If it's not-so sharp, not as clean, but less risk of wire damage I would think.
As sharp as possible, scoring then only requires very light pressure and is easily controlled.
Blunt knives are useless as the amount of pressure required to score depends on how worn the blade is, and having to apply extra force means it's more likely to slip and cut things you do not want to cut.
Sharp blades are always the easiest and safest to use whatever you are trying to cut.
John im fitting a cctv camera to the outside of my property. It comes with its own junction box twin and earth connection. Im using standard 1mm cable as its a standard camera low wattage. Immdrilling through from the outside wall into a bedroom. Is it better to use a stiffer cable or flex for that job or doesnt it make a difference
No difference, and 1mm² will be easily large enough.
Why can't they just build a earth wire with sleeve already in.
Because it's not a current carrying conductor. Sleeve is for identification.
They started putting a sleeve onto the earth in 2.5 mm² I think last time I used it only about 1-2 months ago
Jk957 We use those here in Germany, for almost everything. But cables in walls are mostly individual conductors in plastic conduit.
Hi can you clarify for me if I can use 2.5mm yellow Arctic cable (110v) to make a 240v extention lead thankyou.
Yes, it's all rated to the same voltage. Only the colour is different (blue or yellow).
John Ward thanks for the info and speedy reply much appreciated.
One question which might be addressed is how long tails out to be cut.
Great video and very witty I’ve subscribed for more 👌
That was some brilliant instruction and detail. Thanks Mr Ward
In North America, the active wire is black and the neutral is white. If there are 2 active wires, one is black and the other is red. The earth(ground) is bare with no sleeve.
I've found plasters using plastic floats. This should stop the cable bing damaged. Might even save the plasterers getting arrested should police get into their tool bags !
To strip cable push a knife down the .
Middle
3
Another method of stripping the cable I was shown whilst at college was at top of the cable by using a knife and strip down towards the bare earth without trying to cut through the insulation of the wire. I did it initially lol but mastered it in the end
What a long way round to strip a cable neatly.
I like the pliers which grips & then strips in one operation... a single-handed job... 😎
U didnt mention the risk of nicking the copper whilst stripping it, thereby leaving a stress-point where the copper can fracture & break away.... seen this many times...😞
I am doing this just to leave the silver discs on the floor for the kids looooool.....Love This John!
Ha! Even I know it takes a lot of force to stretch copper, and I'm a complete dumbass!
Hello John
Great Video...........I watched nearly all of your videos
But can you advise what best way of joining inline a 10mm cable ie, connector strips etc?
Your opinion on this is greatly appreciated.
Thanks
Hi John, if this cable was plastered into a wall, it would mean destroying the house to rewire in 40 - 60 years time. Leads me on to a general question, during rewiring does it mean ripping up floor boards and digging through plaster or is the old wiring abandoned and horrible plastic trunking installed all over the house?
Rewiring can be done with surface trunking, but that's normally only used when it has to be done as quickly and cheaply as possible.
If the old wiring is in concealed conduit then that could be reused, but if not, or if things are needed in new locations then concealed wiring does mean chasing out walls, lifting floorboards and so on.
Thoughts;
I'll use a stanley where convenient if I want a particularly nice finish. Not convenient for C.U. wiring for the most part, where I use the snip-into-the-end-and-pull-the-earth method, then snip the outer with the snips, not stanley, as there's too much risk of slicing into another wire in tight spaces (not advised when working live = often), alongside the distinct possibility of sliced fingers. Also seen too many instances of careless stanley work resulting in exposed live conductors, including some pretty nasty faults in damp environments (blown SWAs at the gland). As a rule, when I use a stanley, if I cut too deep then I cut the length off and start again (assumes you have length to spare in the first place). Score the outer only...
Stripping the inners - My 1.5/2.5/+ strippers of choice are my quite old but still awesome Kew Technik snips that snipped through a live 1.5 T+E many years ago ("power off mate?" - "yeah" - *snip, bang* - "nope..."). Amusingly it blew two small holes of different sizes in the blades - one being great for 0.75-1.5mm, other being perfect for 2.5.
I always try to double-over exposed conductor ends where the terminal they're being fixed into allows for it (particularly if only hosting a single conductor), especially the thinner earth. I see this as creating a better contact (lower resistance) due to increased contact area, allows for higher clamping force, reduces localised heating at the connection, and increased resistance to breaking the core in the terminal where an over-tightened screw may otherwise crush the copper.
T+E cable = for fixed installations only. Don't do as some do and stick plugs on the end of it to be used as a substitute for flex cable...
I prefer to use capping if I C.B.A. purely to allow for the possibility of pulling in/out cables at a later date if required (better than having to chop back into that newly plastered/decorated wall...).
If I'm dealing with metal back boxes I tend to add a 1.5/2.5 G/Y length of 'singles' wire from it to the socket/switch/etc. where appropriate. Better that have a back-box potentially go live if/when the plate is pulled away sometime.
Thanks for taking your time to do these videos, JW. Always informative, and food for thought.
+9ff70f96 Majority of the time i use the snip-into-the-end-and-pull-the-earth method, then snip the outer with the snips as it saves sooo much time and as its always said, TIME IS MONEY!! CK, NWS and a few other brands make snips that have built in 'strippers' for 1.0/1.5 and 2.5mm 2 cable, very handy in tight spaces! Only down side is when you need to cut a bigger cable ie 6mm up, you need to make 2-3 passes as you don't have a full length blade. As for earthing back boxes, I tend to leave an extra 4-6 inches of T+E on cables in back boxes during 1st fix so that during 2nd fix, you snip off the extra cable, remove ONLY the CPC and terminate in the back box with a piece of earth sleeving then to the faceplate weather it be socket, switch, cooker isolator etc.
“foxes coming along and chewing it...” Gosh that’s made me chuckle...
I really appreciate your expertise in this area. I don't like wire nuts and was interested in learning about other ideas.
Thanks I found that really useful... As a novice it's really helped me
Happy days on the stretching myth glad somebody with some sense said it 👍
old generation loves single wire per line
Really helpful video thank you
Sorry if I missed it but what do you think about folding over the ends?
I always did it, but on ring circuits to sockets now I'm wondering if it makes a cleaner, more certain/secure connection without, especially when replacing sockets in tight spaces.
"Theoretically" a doubled/folded over end could snap under the terminal or when pushing the socket into place.
Depends on the size of the wires relative to the size of the the terminals. With multiple wires it may not be necessary or even possible to fold the ends, but certainly recommended with only a single wire and a relatively large terminal.
@@jwflame Thank you, that's more or less what I thought.
I wonder if someone will try inventing a socket which takes wires with a Wago style snap terminal.
I have never seen that green/yellow sleeving before and I can't seem to find it even now. It seems like a handy way to reduce the chance of accidental shorts. Is there another name for it? It is a UK only item?
It's just called PVC sleeving, this is a random example: www.cef.co.uk/catalogue/products/213784-3-0mm-green-yellow-sleeving-100m-reel
It's only common in the UK because of the type of wiring - the flat cable doesn't have any insulation over the earth conductor. Other countries use cables with the earth conductor already insulated in green/yellow, so there would be no need to use separate sleeking there.
@@jwflame All the home electrical wire I've seen or worked with in the US has a bare earth conductor. As far as I have seen, they are always just left bare in the box. I'm not sure why we (Americans) didn't get the memo on this. Maybe because our voltage is lower? I can't seem to find that material anywhere and I've never heard of anyone sleeving before watching this video.
Informative video.
I love practical videos
My wire strippers are a good time saver and also leave a clean cut end
I wonder if you use round wires, like the NYM standard, in the UK?
I hate flat cables and never use them. Such a pain to strip compared to round ones.
Round ones can be obtained but are seldom used, most building wiring is either the flat T&E as shown in the video, or single insulated wires inside metal or plastic conduit.
John Ward
Thanks for the reply.
why does the earth not come sleeved
Cheaper
Thousand of kilos Ehhhhhh lol
greetings, in Australia they used to the solid core cable, that changed years ago to multi strand, including the earth wire insulated. Do you see any advantages in solid or multi strand, what are your thoughts on both.
We have NEVER ever had a non stranded earth conductor in Oz, bare yes, solid never, solid cable was only ever used by cheap arse shit contractors because it was around half a beer cheaper than stranded cable per drum to purchase, the earth has always been stranded originally three strands now minimum of seven, the earth is the most importaint conductor in the circuit.
On a side note, thats why earth pins are the longest pins in plugs, and why the earth pin is the bottom pin in Aussie sockets, so if the plug is hanging out of the socket the earth disconects last.
Yes ,well my house in Australia is all solid core cable, not stranded at all.....I have lots of friends who I have checked there house and it's all solid core cable.....this is in Brisbane.......what are your thoughts on solid verses stranded cable, what do you think is best....thanks....
Thanks JW another well explained subject.👍
God you're good !
I'm learning loads - Many thanks.
hi john great vid,how do you make a right angle with pvc trunking? many thanks
Either cut a 45 degree angle in each end (making sure you cut the angle the right way), or just butt one piece up to the other at 90 degrees leaving the ends square (my preferred method), and trim with snips to allow the wire/cable to pass through the bend. Or you could go the quicker but rougher and more expensive route by buying 90 degree caps of the appropriate type (internal/external/etc bends) to cover-up gaps in your cuts (finished job tends to look worse, in my opinion).
jw you are a fantastic teacher
Thank You JW. A really good video.
Also when removing insulation try not to cut in to the conductor as this could reduce the csa of the conductor and may introduce a fatigue area (where if it bent too much it could fracture on the cut area)
Thanks this was really helpful
oh and also I use the cheese wire method of striping the insulation!
kind regards Warren
Warren Grey, That method has a bending and straightening process that work hardens the copper conductor, leaving it more brittle.
@@johnbower Doubt it matters.
Hi John, just to chip in its also a good idea to warm cable before installing to avoid breakages
👍👍👍👍👍Great video!
JW superhero
Great video
Are you not supposed to earth the metal back box as well as the outlet?
That's a can of worms. Some people claim that you don't need to if there's a solid lug (that's per the regs, I believe.) but to me it's simply unprofessional not to. Because the guy who mentored me when training me [mumble] years ago... would've torn me a new one if I left out the earth flylead!
yes its should be
I moved into a newly built house in 1999. About 5 years after moving in one of our kitchen sockets started playing up - one of the switches gone u/s. On fitting the replacement socket - discovered that no earth lead fitted to the metal box earthing terminal-I rectified that. Being a curious chappie I went round the whole house to check all other sockets- none of the back boxes had the earth lead fitted - they do now! Still my house - my responsibility.
The sockets are designed with metal collars connected to the earth on the socket connector. In principle, when you tighten the fixing screws up, they will also earth the box too. However, for some that's not enough.
@@TheEulerID JW has a video of a BS socket outlet where the ground strap does not extend to the fixing holes and so would not be made to the back box. Better to make a real connection to the box in all cases. ruclips.net/video/kPpX1YXvGcg/видео.html
i managed to stretch couple of earth conductors by pulling throughout the cast copex in concrete, i used metal draw wire and i applied my body force to pull them out from the socket, but that happens only if you attach the earth conduit to the metal draw wire and only for distances like 3-5 meters long, you can spot that the earth wire is longer and thinner but not broken and the 1.6 formula for testing would fail by a small margin
Thanks J W!
Bad video never use a sharp knife to skin cable. You’ve just cut into the copper core and weakened that wire at that point
Rizwan