The Earth Wire is Missing! - Can You Use Steel Conduit Instead?

День тому

In our Conlok conduit installation video, we explored the electrical continuity of the full electrical installation. In most electrical installations today, most circuits are wired with a dedicated circuit protective conductor (CPC). Do you have to include a CPC conductor when using a metal conduit?
We'll explore the use of steel conduit as an earth conductor and how it's applied to multiple circuits contained within the same conduit or trunking.
Check out the Conlok Conduit System
👉 • CONLOK: Will You Ever ...
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🕐 TIME STAMPS 🕕
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00:00 Can I use steel conduit as a CPC
01:06 What can we use as a protective conductor
02:54 CSA is important
04:43 More than one circuit
06:35 Line conductor size (S)
08:14 k1 and k2 values
09:03 Table 54.5 k value for steel conduit
10:38 Calculation
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#efixx #electricians #conduit

КОМЕНТАРІ: 138

@efixx Рік тому

Check out the Conlok Conduit System 👉 ukposts.info/have/v-deo/pWd_dmONkXiTumg.html

@andysims4906 Рік тому

I was on a job in a garage a couple years ago . The conduit appeared ok but I was a bit sceptical. . On pulling in new cables I found the existing conduit under the concrete floor was In fact very rusty and as I pulled the old cables out they were very wet and stained by the rust. Moral of the story is unless you can see the whole length of the conduit don’t trust it for earthing.

@sergiofernandez3725 Рік тому

Lots of good stuff there. My opinion is run a separate CPC in the conduit and the same for SWA and stop trying to save money at the design stage. A main reason is that it may work and be ok when first installed but what happens when some of the joints start to work loose or the conduit/SWA armour starts to carode/rust

@Maureen-kc4cm Рік тому

The system should be periodically tested so that would be picked up on but I'm just being arguemnetative because I fully agree with you run the CPC

@leeroberts5193 Рік тому

Love these videos and the way Joe explains them. Anything that simplifies and better explains the regs and their application is worthwhile 👍

@jamesbrett5010 Рік тому

Different terms with the NEC over across the pond. We no longer allow mechanical means from faulty connections. We run an equipment grounding conductor with every run and bond every box with a splice. Simple and redundant.

@StreamFeeds Рік тому

I’d run the separate CPC just for good measure. I have never ran it any other way. When doing my 2365-2 they taught me that way so that’s the way I’m going to do it but never the less joe, amazing information you have provided

@bambibigboy Рік тому

Thanks Joe. Brilliant video as always. Cheers Craig 🙂👍🏼

@Ant86744 Рік тому

I never got taught on how to do this calculation at college so thank you. During my apprenticeship I just got told it’s fine for sockets to use the steel for the earth but never why in steel conduit. I never did though rely on this and always added that 2x1.5 or 2x2.5 earth in.

@gbelectricks Рік тому

Bloody clever stuff Joe!! 👏 👏

@efixx Рік тому

Nah, just lots of reading! 😂

@gbelectricks Рік тому

@@efixx that’s the problem they pass you from pillar to post and back again before you get the answer!! Top work men👍

@dennisphoenix1 Рік тому

The issue here would be the Zs values measured at the farthest point and the likely hood of an increase in resistance from corrosion or vibration etc . Just install a copper cpc and don't worry about it

@paulmatthews5470 Рік тому

Could use an RCD as you would with a TT install as they seldom meet the required Zs as well

@dennisphoenix1 Рік тому

@@paulmatthews5470 yes you could .

@bernardcharlesworth9860 Рік тому

Have found corrosion reduces zs so I alway include a earth cable

@dennisphoenix1 Рік тому

@@bernardcharlesworth9860 reduces Zs ??? Surely increases Zs , decreases fault current ?

@andrewwhite3793 Рік тому

I served my time on the 14th edition that stated the containment must be electrically & mechanically sound. When the 17th came out a lot of young sparks were failing installations as the "CPC" was missing and some ran them and removed the earth leads from the back of the conduit box

@johnburns4017 Рік тому

The socket retaining screws will make the earth to the back box and hence the conduit.

@cal5566 Рік тому

If I was doing my own workshop I'd work everything out and give it a go, but doing it for some one else running in a separate cpc is definitely more sensible.

@efixx Рік тому

Yeah we tended to lean that way on site as well. 😊

@essdee9143 Рік тому

Using the new conlock conduit system and assuming all freshly cut conduit ends have been painted (to prevent corrosion) then wouldn't the conlock grub screw be the only true metal to metal connection...? So shouldn't this whole calculation be based around the CSA of the conlock grub screw..? Or am I missing a trick where the protective coating of conduit paint is actually conductive..? Your thoughts please..? Great video as always guys 👍🏼

@JimWhitaker Рік тому

Conduit zinc coated? If so that leaves the contact being the grub screw and a line contact at the opposite point from the grub screw. Also what torque are you using for that screw? Not convinced.

@eddie_pegasus_electrical Рік тому

Good explanation Joe 👍

@JamesCurnowElectricalEngineer Рік тому

Interesting topic. Most of the projects I've worked on over the years, the contractors have always used a separate cpc, as it's easier. However it's definitely worth bearing in mind situations where we can use conduit as cpc, especially if you find it when carrying out an eicr.

@efixx Рік тому

Yeah, we tended to run an extra CPC in steel conduit as well, quite interesting to see where the cut off point is for using 20mm conduit as the CPC too.

@johnburns4017 Рік тому

Using the conduit as the CPC is only done in big commercial jobs. Done in a big job I was at in the Middle East - to US standards which were more 1930s. Saves a lot of earth wire on a big job though. Quicker to wire up as one less conductor to manipulate dress and tighten up. Done a lot in ye olden dayes when copper was very expensive.

@essdee9143 Рік тому

@johnlloyd3377 Рік тому

@@essdee9143 Great observation.

@seandempsey7351 Рік тому

If I remember correctly you can use metal conduit as an earth conductor really it’s no different to using pyro, but I think it’s would be better to run a separate earth lead , just to make sure Fantastic video as always Joe 👍👍👍❤️

@efixx Рік тому

Thank you sir.

@seandempsey7351 Рік тому

When is the next live show? Is it tonight or next week ?

@mikeselectricstuff Рік тому

But with that grubscrew-fixed system, all it would take is one loose grubscrew, or a bit of corrosion etc. at the fixing point and suddenly you have no cpc.

@TeamSimpsonRacing Рік тому

Thats only the same as the first cpc connection coming lose (if a radial)

@dglcomputers1498 Рік тому

I suppose adding grounding straps at each join in the conduit could be mitigation against that, although if going to that kind of detil you might as well just add an extra earth wire.

@njwareing6408 Рік тому

This is handy for an EICR on older Installations intended to use the conduit for the CPC, a lot of electricians would automatically fail the installation based on no seperate earth

@batmanpaul1 Рік тому

Fantastic video 👌🏼👍🏼

@christastic100 Рік тому

This is an absolutely brilliant vlog . Very informative and helpful. I have never in the years used the conduit or trunking as the CPC but I would consider it. The only question I have is where the trunking enters the accessory/consumer unit/ dis board or whatever require special attention regarding cleaning off paint to ensure a proper long term connection. It’s a bit like the question of SWA gland tags not being used on a steel enclosure.

@efixx Рік тому

Good question, we'll do some digging. 😊

@StreamFeeds Рік тому

That’s a well good question… hope we get some good answers as normal back!

@mastergx1 Рік тому

When I was taught this in college - it boiled down to one simple fact for me... when it comes to 20 & 25mm steel conduit. If you can fit the line conductors in the bloody pipe, it will always be a suitable earth.

@jimbojones9813 Рік тому

Your comment made me chuckle, unless you got a paper thin conduit

@tsheritageengineering Рік тому

About 50 years ago I used to find a lot of gripfast conduit which used clamps to join fittings, the paint had to be scraped off to ensure continuity and it was wired in singles VIR cable. Guess that was from the 20s. Looks like conlock is the modern equivalent!

@AbdulAminGani Рік тому

Doesn't the grub screw reduce the cross sectional area? It only makes contact that you can rely on on the tiny screw, not the whole conduit

@cncshrops Рік тому

I had the same thought. I certainly don't think that the contact between conduit and fitting in this sort of push-in setup should be relied on as a dependable connection.

@jfbeam Рік тому

There's also the the part being pushed against the back of the housing, but yes, the entire conduit is not the contact point.

@BrianWrenn Рік тому

so the CSA might be only 60/70%... earthing conduits is a must, but in my view always run in a earth also

@dononebullen Рік тому

@@jfbeam the painted part

@johnburns4017 Рік тому

I have seen square metal trunking as the CPC with cable bolted to the trunking at the corners and tees. Seen one where the trunking was played about with, having the cable CPC left off. Big break in the CPC.

@efixx Рік тому

Sounds like a problem... 🤔

@johnburns4017 Рік тому

@@efixx Always check, that the trunking is linked by bolted conductors.

@leewakefield8658 Рік тому

While the CSA of the conduit itself is sufficient, what about at the joints? As the joints are held together by a set screw, do you need to calulate the area of said screw as that is like to be less than the area of a conduit?

@TitchgamerRG Рік тому

I have used the SWA as a CPC before on very large cables, But only when forced to do so and never used conduit or trunking as one. Otherwise I run in a CPC every time! Having seen some conduit installs I would never trust them to be a earth personally.

@njwareing6408 Рік тому

I have done a job a few months ago and the client wanted galvanized conduit, I wish that I had discovered this conduit system, it would have saved a lot of time threading the conduit. lol

@dannyte83 Рік тому

Great refresh from college 👍🏼😂 but definitely don’t get paid enough for all that lol

@dansheppard2965 Рік тому

This bit of the regs seems crazily weak. The end-to-end resistance of runs must be very unreliable even if you manage to get a good reading at installation. This stuff gets knocked and there's ingress of dirt, corrosion, etc, all the time especially there steel conduit is specified. What's the point of getting the torque correct to the nearest 0.1Nm in a distribution board and then relying on a grub screw or on-site threading and attaching it to a 2m lever arm? I guess it would be ok for RCDs where the CPC is just needed to sink enough current to trip it, but where you're talking about equipotential bonding or relying on fault overcurrent to trigger protection you need your CPC to be treated with the same respect as line conductors (except that you can assume its loads are transient in terms of heating).

@essdee9143 Рік тому

To be fair as an X electrical sub contractor, I have never once relied on any metal conduit or trunking for a CPC for two reasons that superseded all other considerations... 1, when you are on price work time is money and you simply don't have time to waist on another calculation.. 2, when a simpler solution already exists (ie running a separate CPC) then all you'll be doing is waisting time and money exploring anything else.. Real world electrics fellas..! However this is a very interesting topic, keep up the great work 👍🏼

@tilidie5272 Рік тому

at the consumer unit side of things would you connect the conduit to the earth terminal or no? or dont you need to because its fixed to the consumer unit?

@andrewwhite3793 Рік тому

I served my time on the 14th edition and the regs stated the containment should be electrically & mechanically sound ie an earth. When the 17th came out there was young sparks failing an installation due to no CPC .

@dangraves7808 Рік тому

I did an eicr on a school years ago when I was an apprentice and the conduit was used as the cpc all the readings were better than expected due to the conduit and parallel earth paths of the metal fabric of the building Had the nic assessor out at one point and he was arguing saying our readings couldn’t be correct! The sparks I was working with ran rings around him😂

@PhilipVeale 6 місяців тому

Is there no significant difference in resistance/impedance between the steel conductor and copper when making these calcs?

@peterconnolly4608 Рік тому

Better to install copper cpc in the event of external fixtures been added later on , Bit like underfloor heating pipes now in plastic covered and aluminium layer inside ,after time on radius the lining will have wore away with aluminium in contact with water , future problems ,

@christopherhume8896 Рік тому

When I was first on sites we used the conduit and trunking as cpc but after a few years running a cable was specified. I can only assume it was down to the designers, the same muppets who wanted us to get 6 x 4mm singles round 20mm pipe bends. Real Fairy Liquid job that one. 🤣

@efixx Рік тому

😂 Having been on both sides of that fence I totally sympathise Christopher.

@Mike_5 Рік тому

The relatively cheap cost of a copper CPC versus the Court Appearance for Health & Safety failings makes economic sense for any professional

@richjones2767 Рік тому

How do you ensure a low impedance ground connection to the surface mount boxes, they're usually painted inside and out but no one ever mentions removing the paint, do conduit fittings cut through the paint reliably? Am I overthinking it?

@deang5622 11 місяців тому

Remove the paint or don't use that type of box. Commonsense should tell you you shouldn't be making an electrical connection with a layer of paint in the middle - unless it is purposely designed as electrically conductive paint... You are allowed to think for yourself.

@dvrn86 Рік тому

Perfectly fine in canada to use steel conduit as your cpc.

@noworriesnoproblems6382 Рік тому

I ve used plastic conduit for the earth before.

@easayas123 Рік тому

🤣🤣

@mb-electricalservices Рік тому

🤣🤣🤣😁

@muzikman2008 Рік тому

I struggle to find pvc 20mm banjos though.. Or I would too 🤣👍

@noworriesnoproblems6382 Рік тому

@@muzikman2008 wrap it around the thread of the male adapter derrr

@muzikman2008 Рік тому

@@noworriesnoproblems6382 good idea, I'll use that technique on my next high integrity earthing install 💡😂 maybe some pvc cement to hold it in place as a safety measure..

@TheManLab7 Рік тому

I wouldn't personally. I've always used an earth wire and fly leads for armoured, even if it's in metallic. Pyro's a little bit differently as the outside is the earthing and it's connect at both ends for the earthing.

@jfbeam Рік тому

I know code allows it, but I hate seeing people "cheap out". All it takes is one loose screw to break the ground. Or a conduit being cut, or section of plastic being introduced to screw everything up. And of course, sparky's and inspectors never actually check. (I've seen lighting circuits where the conduit wasn't secured at couplers or boxes. Inspectors never climb into the ceiling and pull on things.)

@johnhoward2104 Рік тому

Interesting video, as always. To save people time measuring/calculating conduit/trunking CSA's, Table D5 of GN 1 gives the values for common sizes - simples😃

@garethfraser5211 Рік тому

If I was going to consider using the conduit for the cpc, I definitely wouldn't be happy with a small grub Screw making a secure connection and continuity. Crap system, much better job to thread the pipe. Quicker is definitely not better in this case.

@JimWhitaker Рік тому

Depends why you are using conduit surely? Mechanical protection? - frankly a slip joint would be fine. Electrical continuity? Whether CPC or to meet Tempest requirements, screwed seems much more robust.

@stevethomas5849 Рік тому

that picture of the Bush into the box looks like a black plastic ring

@juliancantarelli Рік тому

Where do you study to become an electrician in England? Do they accept foraigners? I'm from Argentina and looking for "new horizons".

@leewinters606 Рік тому

Yes as long as you are pleasant.

@nw5835 Рік тому

@@leewinters606 and don't insist that the Falklands..................

@daviddearden6372 Рік тому

What happens when you have dissimilar metals,say steel conduit and an alluminium box/enclosure. In this example crystaline corrosion will set in with even a little dampness. Do the regulations say anything about this?

@deang5622 11 місяців тому

It's called galvanic corrosion.

@jamespunchard7106 Рік тому

How would you ensure that the conduit itself is connected to an earth?

@deang5622 11 місяців тому

Drill a hole into it.

@blobstrom Рік тому

Old commercial buildings use the conduit/trunking as the CPC

@efixx Рік тому

Yup!

@_eusty Рік тому

Yup and I work in a factory like that. Seen lots of missing trunking and corroded conduit. 😳 Always have put a separate CPC apart from large SWA's when installing.

@stevendouglas3860 Рік тому

No . I think. 🧐🤔 I'll check the code

@johnburns4017 Рік тому

How are you connecting the steel conduit to the earth bar in CU?

@reddie8130 Рік тому

Connect a fly lead using the banjos bolt and nut

@johnburns4017 Рік тому

@@reddie8130 I assume that can drop to 1.5mm if using 2.5mm rather than 6mm.

@rossthompson1936 Рік тому

@@johnburns4017 you can’t mix and match the calculated CSA and selection. If you are using selection as the video, then you should use the same CSA as the circuit line conductors. In which case it would be 2.5mm to the socket earth terminal. If you used less then you would need to prove it by the calculation. Although in practice you will almost always be able to reduce it.

@johnburns4017 Рік тому

@@rossthompson1936 So using the conduit it would be min' of 6mm cross section area of the conduit. If mixing it with cable the minimum size of the CPC is the size of the conductor in the cable, say 2.5mm

@rossthompson1936 Рік тому

@@johnburns4017 it’s important to remember what you’re trying to do. In the video the CSA of the cpc is to be selected rather than calculated. If you were using copper, it would be the same size as the line - 2.5mm. But here steel is being used hence the k1/k2 calculation, which says the steel must be 6mm min. But if you are connecting the conduit to the accessory earth it’s going to be copper. Hence 2.5mm same as the line as per selection. If you calculated instead both the steel and copper would be less. Therefore you’d probably get away with 1.5mm. But you started with selection and should continue to do so unless you make the calculations.

@Maureen-kc4cm Рік тому

Soooooooooooooooo. Can we use the conduit as CPC or what

@johnlloyd3377 Рік тому

All very true no doubt....but not the kind of thing to spring on a chap in the morning with a sore head😄😄😄

@efixx Рік тому

🤦🏻‍♂️👍🏻

@phildxyz Рік тому

So really, for all likely sizes of conductor in a 20 or 25 mm steel conduit the conduit will be fine as the CPC...

@efixx Рік тому

Yur, the cable needs to get pretty maohoosive before it becomes non-compliant to use the conduit.

@dononebullen Рік тому

No flying lead one thing no earth is another ... I wouldn't rely on that now days when I find old systems like this I add an cpc personally

@jamesandrews8391 Рік тому

That was how we used to do it,conduit was the earth. Waitrose supermarkets was the last place I used conduit as earth,their spec,that was 25 years ago. There was a specific tester for conduit earthing if I remember correctly.

@odinnln5694 Рік тому

My head hurts.

@efixx Рік тому

It is a bit heavy

@muzikman2008 Рік тому

Adiabatic equations or just run a cpc? Hmmm... Good practice to just run a cpc me thinks 🤭

@MrSJT Рік тому

Don't you have to divide that figure by 8 due to poor conductivity of steel compared to copper like you would when using the armour of an SWA cable for your CPC?

@cal5566 Рік тому

Looks to me like the k2 value here factors in the lower resistance but I may be wrong.

@efixx Рік тому

This. 👆👍

@MrSJT Рік тому

@@efixxcool 😎

@AAW-Electrics 3 місяці тому

Interesting to also watch this video: ukposts.info/have/v-deo/rJSCf6mihYN_w6s.html by John Ward. Although, I personally (or professionally) wouldn't use that ConLock system if using the conduit as the CPC, only the traditional screw in type.

@AAW-Electrics 3 місяці тому

? Pi x 8.63^2 = 233.98 and not 244.95???? Still, makes no difference to your proof that the steel conduit is plenty fine to be used as the CPC in this instance. (314.16 - 233.98 = 80.18 mm^2 CSA for the CPC...)

@computeraddic675 Рік тому

Use plastic sockets!In Europe it works,so why not in the UK?

@seanthespark Рік тому

We use metal where the environment demands it, mainly in commercial and industrial sites as it stands up to any potential damage from fork trucks etc, plastic would just smash. However there's is a increasing trend to install metal conduit and metalclad accessories within homes for aesthetic value (the industrial look).

@computeraddic675 Рік тому

@@seanthespark I have bin in lots off factories in the Netherlands and no metal sockets seen or installed!

@AndrewLumsden Рік тому

Would seem sensible to earth any metal trunking/conduit etc. anyway, whether or not there is a cpc. Back boxes are generally earthed and a cable could get snagged when passing it through the trunking/conduit, making it live.

@efixx Рік тому

If the conduit is the CPC would that snagged cable situation not then disconnect the protective device? 🤔

@AndrewLumsden Рік тому

@@efixx Indeed, but if not earthed it would remain live (?) Is it not the equivalent of a water or gas bond? - even if it doesn't go fully into earth.

@johnlloyd3377 Рік тому

@@efixx Being pedantic here.....but you mean TRIP the protection device😁

@markbradley5746 Рік тому

I do appreciate all the math and science that goes into cable calcs and one reg that that refers to another reg providing 2 other regs are met and they all satisfy another reg....🤨 Do you know what..... my time is better spent on the tools rather then at a desk with a calculator and 9 of my fingers in different pages of the reg book and its tables... Sorry but im just gonna buy a couple of coils of earth wire.... If you have a few guys in your company and one of them can do all the paperwork and calcs then crack on.... but if your on your own then you need to be earning the monies.... And beside the most important fact....Bar none is conduit , bushes, couplers nuts etc are absolutely a load of cheap crap.... and it dont matter where you buy it from... its crap, threads are very loose and surface areas on bushes are minimum as are gutter nuts..... you compare containment quality from late seventies early 80s to modern metalwork and your mind will be blown... British Standards must be getting brown envelopes from someone on a regular basis because quality has gone down the toilet... FACT... I wouldnt fancy a fault current being trusted down the conduit and accessories....

@efixx Рік тому

OK.

@Benzknees Рік тому

If the neutral & earth meet back at the transformer, why do you even need an earth.

@bigissue9179 Рік тому

LIKE WATCHING A DOG SHIT ON YOUR PATHWAY WHEN YOUR SITTING IN YOUR PANTS AND ITS PISSING DOWN WITH RAIN

@jamesandrews8391 Рік тому

If electricians did conduit tightly you got no problems,,with the size of the tube it'll always be big enough for use as earth,just don't do it like that anymore,same as not having flyleads to ceiling grids or radiators,not done anymore,different times.