This popped up today and I remembered the great April fools joke when they said there was a new cable size. 0.5mm squared Twin and Earth. Well people started asking around at wholesalers, people looked it up on the internet and then even the IET got involved and got funny about it as well. It was a great wind up. Really worth a watch. Moving forward. Gaz always refers to this kind of cable as PVC/PVC twin and CPC cable. Examiners want to see it that way and do not like the term earth cable the rest of us call it Twin&Earth or T&E as it has been know for donkeys years.
Another great video, Just to annoy every body and will prob's get loads of replies but the copper wire that's either bare ore sleeved green /yellow is cpc, earth is what we stand on ,normally muddy in the uk with potatoes growing in it. Earth is also the name of our planet.
In Ireland, and most of Europe T&E is basically just a flat 3 core cable (all conductors insulated, all same cross sectional area). New regs here in Ireland which we refer to as IS10101 also call for a minimum fire rating on cable
@@nsoper19 Here in Germany the CPC is fully insulated within the cable since it must be marked green/yellow over the whole length of the cable run. Exception from that are cables with a concentric CPC. Up to 16mm² the CPC must be the same size as the line. Is the line between 16 and 35mm² the CPC must be at least 16mm², from 35mm² on the CPC must be at least half the size of the line conductor. And the 1mm² isn't permitted. Smalltest copper conductor size for fixed installation is 1.5mm², for aluminium it's 16mm². The aluminium size is since 1973 in West-Germany and 1990 in East Germany. In East Germany they used a lot of aluminium conductors. It's not only about current carrying capacity, this is due to mechanical stability, bending radius, damaging the conductor while stripping and such stuff. And here the conductors are solid up to 10mm², so the stranded versions are starting from 16mm² here.
In Germany most cables are round shaped, not flat. Only type that is flat is NYIF, but no one here uses it anymore. Back in the old days it was a cheap alternative, but you can only use it in dry rooms, only below plaster, must be nailed to the brickwork and then plastered over, no contact to combustible construction materials. The wires are PVC insulated, but the cable sheath is made of rubber. And now these days it's almost more expensive than the more flexible in its application NYM cable. In some countries like France, these cable types aren't permitted at all. They want conduits with single wires in there. That is one of the three cable types that use the old German cable designation system from pre-European harmonisation: NYIF, NYM and NYY. The old NYA for example was replaced by H07V-U.
@@nsoper19no, it ends up being *a little* wasteful. Virtually all our domestic cabling is 2.5mm^2. You guys run 2.2+2.5+1.5 is 6.5 mm^2 of copper. We run 2.5*3=7.5. The difference is utterly negligible. With cables that thin, the price of the copper itself almost vanishes into the cost of competently making them into cables. We’re allowed to start using “size down” CPCs from 16mm^2 and up, IIRC.
Good info Gaz thankyou, though I am surprisedto hear, knowing how you like to be exact in your teaching, to hear you say millimetre squared rather than square millimetre😉Keep up the good work.
Weird, UK still allows bare CPC??? We in europe no longer allow bare cpc since 2017, plus the cross section of the cpc must match the live conductor cross section
I recall in the 60s when I was doing my apprenticeship there was a copper shortage and our contracting company were installing on a new housing estate . We were given solid core aluminium cable instead of 7/029 for ring circuits and all the electricians were moaning about how difficult it was to push solid core cables into a wall box. The shortage ended after about 4 months. Seems amusing now in todays modern 2.5mm use. I wonder if any of you modern day sparks have seen this cable in domestic homes.
The reason is explained in the video. The CPC does not normally carry load current, and if it does, it's under fault conditions and will be for no more than 5 seconds. There simply isn't enough time for 5 seconds of fault current to generate enough heat to damage the cable. As long as the conductor has a low enough resistance to carry enough fault current to trip the breaker (or blow a fuse) on a line to CPC fault within the defined period. With RCDs and RCBOs it's even less likely that there will be a significant fault current as a fault to CPC of more than 30ma will cause those to trip immediately. Whilst it's possible to construct elaborate failure scenarios such that the CPC is carrying a high current, but not enough to trip an over-current breaker, those are extremely unlikely and, as mentioned, will always trip where there's an RCBO/RCD involved, so that would have to fail as well.
@@TheEulerID yes appreciate that but why does it only apply to conductors up to 16mm. Armoured and other industrial cables, Flexes all have equal size earths. ( too old to call them Cpc's) this anomaly only applies to t&e cable. I expect it dates back to the end of the war when materials were short!
@@johnwarwick4105 I don't understand why we would want to make the CPC larger than it needs to be. As for industrial uses, then the parameters are going to be different. SWA doesn't come in the same colour codes as twin and earth, and doesn't have a dedicated CPC as such. It it is often used in three phase installations, sometimes as start, sometimes as delta. Sometimes the armour is used as the CPC. There are simply too many variables and usage patterns. In contrast, twin an earth is used in many domestics and commercial premises where the parameters of the requirements are well known, so it makes sense to make the most economical cable which suits those needs. If you really want to, you could wire up a domestic property using conduits and singles; there's nothing in the regulations to stop you doing so.
Sorry to be a pedant, but it is not 1mm squared, it is one square mm. One mm squared is technically the same but only for one mm squared and one square mm. For 2.5mm squared (for example) this would actually be 5.5 square mm. That is why it is important to distinguish between 'mm squared' and 'square mm'. If we said 2mm cubed what would that mean? It could only really mean 2x2x2mm, being 8 cubic mm. So why would you say 2.5mm squared when you clearly mean 2.5 square mm?
CPC was most probably coined by a government bod whose job it was one day to check all the electrical terms were prim and proper. You can’t fault Gary because he’s teaching apprentices to pass the exams and you have to use CPC to get the full marks.
Even the manufacturers label on the drum has it as flat twin and earth PVC insulated cable . The some of the tables in BS7671 also have as flat twin and earth
Please don't confuse listeners by saying "one millimeter squared", which is incorrect. The error is better shown with a number higher than 1, for example 4. If I were to say "four millimeters squared" it would actually mean 4mm x 4mm = 16 square millimeters. So please say "one square millimeter", or "4 square millimeters" for clarity instead of "one millimeter squared" .
He was a fantastic tutor in college
Thanks for the 👍🏻👍🏻
this guys been invaluable along my journey to become an electrician
Massive thanks for the comment 👍🏻
This popped up today and I remembered the great April fools joke when they said there was a new cable size. 0.5mm squared Twin and Earth. Well people started asking around at wholesalers, people looked it up on the internet and then even the IET got involved and got funny about it as well. It was a great wind up. Really worth a watch. Moving forward. Gaz always refers to this kind of cable as PVC/PVC twin and CPC cable. Examiners want to see it that way and do not like the term earth cable the rest of us call it Twin&Earth or T&E as it has been know for donkeys years.
Thanks for the great comment Sergio 👍🏻
@@GSHElectrical when stripping cable with cable strippers how do you know its size easily
Another great video, Just to annoy every body and will prob's get loads of replies but the copper wire that's either bare ore sleeved green /yellow is cpc, earth is what we stand on ,normally muddy in the uk with potatoes growing in it. Earth is also the name of our planet.
In Ireland, and most of Europe T&E is basically just a flat 3 core cable (all conductors insulated, all same cross sectional area). New regs here in Ireland which we refer to as IS10101 also call for a minimum fire rating on cable
Doesn't that just end up being very wasteful?
@@nsoper19 Here in Germany the CPC is fully insulated within the cable since it must be marked green/yellow over the whole length of the cable run. Exception from that are cables with a concentric CPC. Up to 16mm² the CPC must be the same size as the line. Is the line between 16 and 35mm² the CPC must be at least 16mm², from 35mm² on the CPC must be at least half the size of the line conductor.
And the 1mm² isn't permitted. Smalltest copper conductor size for fixed installation is 1.5mm², for aluminium it's 16mm². The aluminium size is since 1973 in West-Germany and 1990 in East Germany. In East Germany they used a lot of aluminium conductors. It's not only about current carrying capacity, this is due to mechanical stability, bending radius, damaging the conductor while stripping and such stuff. And here the conductors are solid up to 10mm², so the stranded versions are starting from 16mm² here.
In Germany most cables are round shaped, not flat. Only type that is flat is NYIF, but no one here uses it anymore. Back in the old days it was a cheap alternative, but you can only use it in dry rooms, only below plaster, must be nailed to the brickwork and then plastered over, no contact to combustible construction materials. The wires are PVC insulated, but the cable sheath is made of rubber. And now these days it's almost more expensive than the more flexible in its application NYM cable.
In some countries like France, these cable types aren't permitted at all. They want conduits with single wires in there.
That is one of the three cable types that use the old German cable designation system from pre-European harmonisation: NYIF, NYM and NYY. The old NYA for example was replaced by H07V-U.
@@nsoper19no, it ends up being *a little* wasteful. Virtually all our domestic cabling is 2.5mm^2. You guys run 2.2+2.5+1.5 is 6.5 mm^2 of copper. We run 2.5*3=7.5. The difference is utterly negligible. With cables that thin, the price of the copper itself almost vanishes into the cost of competently making them into cables.
We’re allowed to start using “size down” CPCs from 16mm^2 and up, IIRC.
Good info Gaz thankyou, though I am surprisedto hear, knowing how you like to be exact in your teaching, to hear you say millimetre squared rather than square millimetre😉Keep up the good work.
Thank you for your work 🎉
Excellent video as always. Thank you 🙏
GREAT VIDEO!!!!
Thanks
The terms used to describe the cable - remembered until 1.5 microseconds after license acquired...
Does the twin 4mm also come in 2.5 cpc ? Or always 1.5 ?
Should we not be using the low smoke zero halogen as the standard?
Great question 👍🏻. Thanks for watching. Gaz
Weird, UK still allows bare CPC???
We in europe no longer allow bare cpc since 2017, plus the cross section of the cpc must match the live conductor cross section
Interesting that !
Good cable
👍🏻
I recall in the 60s when I was doing my apprenticeship there was a copper shortage and our contracting company were installing on a new housing estate . We were given solid core aluminium cable instead of 7/029 for ring circuits and all the electricians were moaning about how difficult it was to push solid core cables into a wall box. The shortage ended after about 4 months. Seems amusing now in todays modern 2.5mm use. I wonder if any of you modern day sparks have seen this cable in domestic homes.
Thanks for the information Gary 👍🏻
Nice video 👍👍👍
Thank you 👍
Can we get the size by looking at the cable for somebody who is not experienced? Are there any markings on the cable showing the size?
It is marked on the sheath.
I don’t know where the CPC comes from. Even the manufacturers call their cable Twin and Earth .
Circuit Protective Conductor,aka earth conductor..
Government busybodies
My personal opinion is that all cable should be LSF.
Thanks for your opinion 👍🏻
Well for the last 3 years ish I been using LSF in multi occupied premises even though it’s not specified
@@andysims4906 pretty much so have we.
Never understood how the earth can be less than half the line conductor and comply with even the old regs 14 th when I started.
The reason is explained in the video. The CPC does not normally carry load current, and if it does, it's under fault conditions and will be for no more than 5 seconds. There simply isn't enough time for 5 seconds of fault current to generate enough heat to damage the cable. As long as the conductor has a low enough resistance to carry enough fault current to trip the breaker (or blow a fuse) on a line to CPC fault within the defined period.
With RCDs and RCBOs it's even less likely that there will be a significant fault current as a fault to CPC of more than 30ma will cause those to trip immediately. Whilst it's possible to construct elaborate failure scenarios such that the CPC is carrying a high current, but not enough to trip an over-current breaker, those are extremely unlikely and, as mentioned, will always trip where there's an RCBO/RCD involved, so that would have to fail as well.
@@TheEulerID yes appreciate that but why does it only apply to conductors up to 16mm. Armoured and other industrial cables, Flexes all have equal size earths. ( too old to call them Cpc's) this anomaly only applies to t&e cable. I expect it dates back to the end of the war when materials were short!
@@johnwarwick4105 I don't understand why we would want to make the CPC larger than it needs to be.
As for industrial uses, then the parameters are going to be different. SWA doesn't come in the same colour codes as twin and earth, and doesn't have a dedicated CPC as such. It it is often used in three phase installations, sometimes as start, sometimes as delta. Sometimes the armour is used as the CPC.
There are simply too many variables and usage patterns. In contrast, twin an earth is used in many domestics and commercial premises where the parameters of the requirements are well known, so it makes sense to make the most economical cable which suits those needs. If you really want to, you could wire up a domestic property using conduits and singles; there's nothing in the regulations to stop you doing so.
3 x class 1, 4 x class 2, 😁👍
100% - see description plus a link at the end of the video to class 5 cables 👍🏻
Sorry to be a pedant, but it is not 1mm squared, it is one square mm. One mm squared is technically the same but only for one mm squared and one square mm. For 2.5mm squared (for example) this would actually be 5.5 square mm. That is why it is important to distinguish between 'mm squared' and 'square mm'. If we said 2mm cubed what would that mean? It could only really mean 2x2x2mm, being 8 cubic mm. So why would you say 2.5mm squared when you clearly mean 2.5 square mm?
Where’s the new 0.5mm?? 😜
😂😂😂👍🏻
Ok… without watching the video….
Cable sizes in the thumbnail..
1.0mm , 1.5mm, 2.5mm, 4mm, 6mm, 10mm, 16mm.
Do I win a prize? 😁
CPC sizes?
PS mm2
@@GSHElectrical lol couldn’t be arsed to put the 2 on the end of them all..
@@GSHElectrical off the top of my head,.. no you got me there.. I’ll watch the video lol.
Good video but just repeating the same thing 20 times
Blimey, I’m not even a spark and calling the earth CPC annoys me - why use one word when you can use three 🤔
Beacause that's what it's called
It's been shortened to earth over the years
CPC was most probably coined by a government bod whose job it was one day to check all the electrical terms were prim and proper. You can’t fault Gary because he’s teaching apprentices to pass the exams and you have to use CPC to get the full marks.
Thanks Lee 👍🏻
I’m a Sparky and I don’t ever call it a CPC . As far as I’m concerned it’s a Earth wire and always will be.
Even the manufacturers label on the drum has it as flat twin and earth PVC insulated cable . The some of the tables in BS7671 also have as flat twin and earth
Please don't confuse listeners by saying "one millimeter squared", which is incorrect. The error is better shown with a number higher than 1, for example 4. If I were to say "four millimeters squared" it would actually mean 4mm x 4mm = 16 square millimeters. So please say "one square millimeter", or "4 square millimeters" for clarity instead of "one millimeter squared" .