Capping or no capping?

[Calebp43]

Do you use capping to protect your cables? I recently watched a YouTube video explaining why you should use capping to protect your cables. I personally don't think it's needed for the following reasons;

- it's not in the regs. Although there are things in the regs saying to protect the cable from environmental factors and mechanical protection, it never says to use it. You could make a case for the regs implying too use it but I think it would be a poor case.

- very little extra mechanical protection, if any!

- a lot more time consuming.

- It's more expensive. this can be a real factor for a lot of people. Not a lot of people have the money for a rewire and adding that extra cost could be the difference.

But on the hand it does have its benefits;

- easy to replace cables. If that leg has an issue it's much easier to replace that leg or repair it when the cable has been capped all the way to the box.

- metal capping has more mechanical protection.

- prevents plaster deteriating cables.

All things considered when the choice is mine I think I will put it as an option for the customer for a fee of course, listing the pros of having it.

I'm an apprentice. Should be qualified next year. I would really value your opinions on why I should or shouldn't use capping. I've worked for 3 sparks and neither one have used capping. So I've only ever really heard one side of the argument. Thanks in advance.

 

[Dustydazzler]

Reality is on a 3 bed standard rewire the cost of capping as in cost to buy capping would be 50 quid , so on a £10,000 rewire the cost of capping is neither here nor there

I always tube / cap cables in chases , always have and always will , not using capping would be like not using grommets

 

[Calebp43]

Reality is on a 3 bed standard rewire the cost of capping as in cost to buy capping would be 50 quid , so on a £10,000 rewire the cost of capping is neither here nor there

I always tube / cap cables in chases , always have and always will , not using capping would be like not using grommets

Okay so £50 isn't a whole lot tbh. Taking into account not using cable clips etc. Fair enough. But then there's the fact that it takes longer to fit that, than to clip the cables. You told me earlier it would take like an extra minute to fit that in a chase than clip cables.. is that exadurating on your part? Taking into account all different types of walls how they're all easier or harder to clip or fit the capping.

I strongly disagree about comparing it to not using grommets though I must say. Grommets are much more effective at preventing mechanical damage and that's a fact.

 

[Dustydazzler]

Okay so £50 isn't a whole lot tbh. Taking into account not using cable clips etc. Fair enough. But then there's the fact that it takes longer to fit that, than to clip the cables. You told me earlier it would take like an extra minute to fit that in a chase than clip cables.. is that exadurating on your part? Taking into account all different types of walls how they're all easier or harder to clip or fit the capping.

I strongly disagree about comparing it to not using grommets though I must say. Grommets are much more effective at preventing mechanical damage and that's a fact.

To 'me' not using some tube or capping would be 'like' not bothering to use a grommet

 

[Calebp43]

To 'me' not using some tube or capping would be 'like' not bothering to use a grommet

But.... Okay

 

[nicebutdim]

I don't want this to seem untoward, but reading a discussion among electricians on the relative merits of capping is like debating which type of rock is best for hunting deer with.

There are better ways of containing and protecting cables, now please excuse me while I take cover for the remainder of this debate

 

[Calebp43]

There are better ways of containing and protecting cables, now please excuse me while I take cover for the remainder of this debate

Before you go... What are the other ways? Genuinely curious. Don't mean for this to be an argumentative discussion. Again I am only an apprentice and value everyone's opinion

 

[nicebutdim]

Before you go... What are the other ways? Genuinely curious. Don't mean for this to be an argumentative discussion. Again I am only an apprentice and value everyone's opinion

I'm also an apprentice, albeit of the reasonably mature variety.

The relaitve merits of plastering clipped cables, capping and oval or round conduit have been discussed here before, and some compelling arguments have been put forward for each, but in NI all solid wall cable drops are enclosed in round conduit and bushed into boxes and it would be inconceiveable to do anything else.

While I accept there are valid reasons why people might choose not to do this, it protects from trowels and future proofs installations to a reasonable degree. It's also fairly inexpensive.

 

[brianmoooore]

Oval conduit is the obvious 'other' method that comes to mind. Used it all my working life. Take the end of the conduit right into the metal box, then no grommet required.
Cables buried direct in plaster is the mark of a cowboy to me.

 

[SparkySy]

I have always used metal capping or plastic tube, the time it takes to fit nowadays why wouldn't you. With modern screws and building materials and allband/ allround most of the time you can screw straight into block ect where a clip would just pull out again. Even drilling if it's hard and self gripping screws takes no time to do + you can usually pull cables out again if the customer change their minds.

 

[Pretty Mouth]

Capping is there to prevent damage by the plasterer, no other reason. Necessary back in the day when wet solid plastering was the norm, as it was likely the trowel would make contact with the cable. The risk of this happening is much lower with dot n dab, and with chases in existing plaster, so not needed so much now. My preferred plasterer asks me to omit it, as he says it causes problems for him.

Easy to replace cables? Sometimes possible, but by no means guaranteed.

Mechanical protection? Not really, see the note on P77 of the OSG that explains why not.

Plaster deteriorating cables? This is a new one to me, can you link to something to back that up? I believe that PVC cables are fine with plaster, and T+E is specifically mentioned in the OSG as being suitable for being embedded in plaster.

I still use it sometimes, as it can be easier/quicker than clipping on some walls, and also for customer expectations. If I'm plastering the chases myself, I don't usually bother.

 

[Dustydazzler]

We could use some nice black plastic flexi-con bushed to each box and taken up into the floor / ceiling void which would make pulling in new cables nice and easy for the next bloke

 

[nicebutdim]

We could use some nice black plastic flexi-con bushed to each box and taken up into the floor / ceiling void which would make pulling in new cables nice and easy for the next bloke

Or rigid conduit and avoid all the snagging that comes with cheap flexible conduit.

Cross the Irish Sea and you'll find this in all homes built during the last couple of decades - prior to that it was oval conduit squeezed into knockouts, but always extending into ceiling voids.

 

[Calebp43]

Capping is there to prevent damage by the plasterer, no other reason. Necessary back in the day when wet solid plastering was the norm, as it was likely the trowel would make contact with the cable. The risk of this happening is much lower with dot n dab, and with chases in existing plaster, so not needed so much now. My preferred plasterer asks me to omit it, as he says it causes problems for him.

Easy to replace cables? Sometimes possible, but by no means guaranteed.

Mechanical protection? Not really, see the note on P77 of the OSG that explains why not.

Plaster deteriorating cables? This is a new one to me, can you link to something to back that up? I believe that PVC cables are fine with plaster, and T+E is specifically mentioned in the OSG as being suitable for being embedded in plaster.

I still use it sometimes, as it can be easier/quicker than clipping on some walls, and also for customer expectations. If I'm plastering the chases myself, I don't usually bother.

This is why I have been taught to chase in deep enough so the trowel doesn't hit. Use the full length of the grinder.

Yes it is easier to replace the cables this way MOST of the time if done correctly. That is with oval conduit though. I should've been more specific.

Mechanical protection is provided with metal conduit. Again that's me not being specific, I assumed you'd pick up what I meant.

Yeah the plaster deteriating was something I literally learned quite recently. Take a look at guidance note 1 - 4.7 materials likely to cause such attacks include:
Plaster coats containing corrosive Salts: lime, cement and plaster.
Some examples of this
Placticisers migrate to ploystyrene from thermoplastic and also other types of plaster (see 7.5 also)

That's fair enough. I have never done it but I've been doing this for 3-4 years only and worked with 3 separate sparks whove never done it. I would be curious to see if it really is quicker because most people I speak to on this tell me that it takes a lot longer.

Thanks for taking the time to create a detailed comment.

 

[nicebutdim]

This is why I have been taught to chase in deep enough so the trowel doesn't hit. Use the full length of the grinder.

Yes it is easier to replace the cables this way MOST of the time if done correctly. That is with oval conduit though. I should've been more specific.

If already chasing deep enough, I'd go the few extra pence on round pvc conduit and female bushes. Much easier to get cables through.

 

[Calebp43]

If already chasing deep enough, I'd go the few extra pence on round pvc conduit and female bushes. Much easier to get cables through.

Can't really argue with that. Easier than oval I would assume. How would you fix it in the chase? All round band or something?

 

[Pretty Mouth]

This is why I have been taught to chase in deep enough so the trowel doesn't hit. Use the full length of the grinder.

Yes it is easier to replace the cables this way MOST of the time if done correctly. That is with oval conduit though. I should've been more specific.

Mechanical protection is provided with metal conduit. Again that's me not being specific, I assumed you'd pick up what I meant.

Yeah the plaster deteriating was something I literally learned quite recently. Take a look at guidance note 1 - 4.7 materials likely to cause such attacks include:
Plaster coats containing corrosive Salts: lime, cement and plaster.
Some examples of this
Placticisers migrate to ploystyrene from thermoplastic and also other types of plaster (see 7.5 also)

That's fair enough. I have never done it but I've been doing this for 3-4 years only and worked with 3 separate sparks whove never done it. I would be curious to see if it really is quicker because most people I speak to on this tell me that it takes a lot longer.

Thanks for taking the time to create a detailed comment.

Ah, I see. When people say capping, I always think of the metal or plastic stuff that you fix over the cables, rather than oval/tube stuff that you thread the cables through (which I call conduit).

I shall have to buy a copy of guidance note 1 then, but it is the first time I have heard of problems with plaster on cables, and I have never come across any obvious damage to cables embedded direct. There is a passage in the OSG app. C warning about possible corrosion by plaster, lime, cement etc, but it is concerned with metal sheaths, conduit, armour and so on, rather than plastic cables.

Just a though - it couldn't be a typo in that text could it? If the word 'plaster' was replaced with 'plastic' the sentence would make more sense.

 

[SparkySy]

I don't think modern Plaster is as harsh on cables. The older lime Plaster and the likes was more of an issue. (Don't quote me on this) But still I would put some containment round it!

 

[DPG]

Ah, I see. When people say capping, I always think of the metal or plastic stuff that you fix over the cables, rather than oval/tube stuff that you thread the cables through (which I call conduit).

I shall have to buy a copy of guidance note 1 then, but it is the first time I have heard of problems with plaster on cables, and I have never come across any obvious damage to cables embedded direct. There is a passage in the OSG app. C warning about possible corrosion by plaster, lime, cement etc, but it is concerned with metal sheaths, conduit, armour and so on, rather than plastic cables.

Just a though - it couldn't be a typo in that text could it? If the word 'plaster' was replaced with 'plastic' the sentence would make more sense.

Agree - I suspect a typo there.

 

[7029 dave]

I like to use oval conduit on my first fix, however depending on the situation nothing sometimes.

 

[AJshep]

Plastic capping on bare blockwork.
Oval Egatube in chases.
Always extended into the ceiling an inch and tight to the KO box, although not considered a rewireable method you can quite often attach and pull new cables down at a future date if needed.

 

[littlespark]

I don’t have much call for capping these days.

Agree that something needs to be used, not just clipped into the channel which can be a job in itself when the blocks are too hard to nail and the mortar is too soft.

A bit of plastic, or tin capping isn’t going to stop a nail or drill, but then, no one should be nailing or drilling into a safe zone directly above a switch anyway.

 

[Calebp43]

Ah, I see. When people say capping, I always think of the metal or plastic stuff that you fix over the cables, rather than oval/tube stuff that you thread the cables through (which I call conduit).

I shall have to buy a copy of guidance note 1 then, but it is the first time I have heard of problems with plaster on cables, and I have never come across any obvious damage to cables embedded direct. There is a passage in the OSG app. C warning about possible corrosion by plaster, lime, cement etc, but it is concerned with metal sheaths, conduit, armour and so on, rather than plastic cables.

Just a though - it couldn't be a typo in that text could it? If the word 'plaster' was replaced with 'plastic' the sentence would make more sense.

Ive never heard of plaster affecting the cables like that either. Someone made the point to me and referenced that..

Yeah sorry plastic I meant to say. Typing this in a hurry whilst working haha

 

[brianmoooore]

It's not just renewing or altering cables that's enabled by using round or oval conduit. How many times have you come across a burnt out socket that's damaged the last couple of inches of wire? If it's in conduit, it's often possible to gently pull down (or up) enough to get back to clean copper.
I've worked on a lot of domestic properties with walls anything up to three foot thick, so often need to position a switch well inside a door reveal. For these, I use convoluted flexible 20mm round conduit, chased into safe zones, to get up into the ceiling void.

 

[BiddeldyBwah]

Don't see the point of it. People say about it preventing plasterers nicking the cables but if they're doing that on a cable set down into a chase they're crap plasterers and i wouldn't use them anyway.

 

[nicebutdim]

Don't see the point of it. People say about it preventing plasterers nicking the cables but if they're doing that on a cable set down into a chase they're crap plasterers and i wouldn't use them anyway.

Little consolation when testing indicates a damaged cable that subsequently has to be replaced. Doesn't matter who pays for the remedials - no one wants to unnecessarily find themselves doing the same job twice.

 

[LastManOnline]

Plaster deteriorating cables? This is a new one to me

I, m obliged to run cables in wavin. I also think it,s better to have that extra layer of protection. That said I have never experienced cables damaged by plaster. Nor heard a fellow spark experience it.
Now a word about capping. Never knew it existed before joining this forum. I think it has great advantages over oval and round conduit. Running cables through oval can be time consuming and rewiring through oval can be extremely difficult.
I just completed my first kitchen renovation using capping. Have been able to leave slack in ceiling and at floor level underneath floor presses which is moving freely behind the capping and can easily be pulled up or down . It's nice to have a little insurance in case any extra slack is required in the future for heat damaged sockets etc

 

[nicebutdim]

I, m obliged to run cables in wavin. I also think it,s better to have that extra layer of protection. That said I have never experienced cables damaged by plaster. Nor heard a fellow spark experience it.
Now a word about capping. Never knew it existed before joining this forum. I think it has great advantages over oval and round conduit. Running cables through oval can be time consuming and rewiring through oval can be extremely difficult.
I just completed my first kitchen renovation using capping. Have been able to leave slack in ceiling and at floor level underneath floor presses which is moving freely behind the capping and can easily be pulled up or down . It's nice to have a little insurance in case any extra slack is required in the future for heat damaged sockets etc

Do you have a link to the Wavin product you use and is it not possible to leave slack in the ceiling with it?

 

[LastManOnline]

Do you have a link to the Wavin product you use and is it not possible to leave slack in the ceiling with it?

Of course you can leave slack in the ceiling with oval wavin but as regards being able to freely pull it down at the socket box?? Difficult at best. With the capping you are basically freeing up a significant amount of space. You in NI use round conduit which is a step up from oval. The capping I find to be a step up again.
I should confess that my capping is customised. I basically use reverse installed trunking minus the lid. It's worked a treat.
Sorry I don't have a link to hand for oval conduit but just Google it on electrical wholesalers.ie

 

[nicebutdim]

Of course you can leave slack in the ceiling with oval wavin but as regards being able to freely pull it down at the socket box?? Difficult at best. With the capping you are basically freeing up a significant amount of space. You in NI use round conduit which is a step up from oval. The capping I find to be a step up again.
I should confess that my capping is customised. I basically use reverse installed trunking minus the lid. It's worked a treat.
Sorry I don't have a link to hand for oval conduit but just Google it on electrical wholesalers.ie

This stuff? Have to say I detest oval conduit for the very reasons you describe and all this time I thought round conduit was used in IE!

Your custom made capping would certainly leave more space than usual to pull slack through. I take it you're familiar with the stuff commonly used in GB?

 

[LastManOnline]

This stuff? Have to say I detest oval conduit for the very reasons you describe and all this time I thought round conduit was used in IE!

Only advantage of oval conduit over round is the shallower chase required. After that it's all disadvantages.

. I take it you're familiar with the stuff commonly used in GB?

No.Have yet to order some

 

[nicebutdim]

No.Have yet to order some

It's very shallow, with a wide edge - the only place I've seen used was on poorly installed pvc windows, where a large window was replaced with two small units and this capping was siliconed over the join. Never seen it used over cables.

 

[BiddeldyBwah]

Little consolation when testing indicates a damaged cable that subsequently has to be replaced. Doesn't matter who pays for the remedials - no one wants to unnecessarily find themselves doing the same job twice.

Someone would have to be unfathomably horrendous at their job to damage a cable to the extent that it needs replacing in that situation. I'm struggling to imagine how one would even manage to do that with a trowel (especially a worn in one) even when purposefully trying to do it. Non issue in my opinion and imo capping is just unnecessary.

 

[nicebutdim]

Someone would have to be unfathomably horrendous at their job to damage a cable to the extent that it needs replacing in that situation. I'm struggling to imagine how one would even manage to do that with a trowel (especially a worn in one) even when purposefully trying to do it. Non issue in my opinion and imo capping is just unnecessary.

I also feel that capping is unnecessary and have stated many times that round conduit is my preferred method of containment, where cables are to be buried in walls.

 

[BiddeldyBwah]

I also feel that capping is unnecessary and have stated many times that round conduit is my preferred method of containment, where cables are to be buried in walls.

Is that what you do in Ireland?

I find that weird that people would feel cable needs containment at all. The outer sheathing is there for a reason otherwise we'd all just use singles.

 

[telectrix]

I don’t have much call for capping these days.

Agree that something needs to be used, not just clipped into the channel which can be a job in itself when the blocks are too hard to nail and the mortar is too soft.

A bit of plastic, or tin capping isn’t going to stop a nail or drill, but then, no one should be nailing or drilling into a safe zone directly above a switch anyway.

but then, no one should be nailing or drilling into a safe zone directly above a switch anyway.

so when is somebody going to tell Kevin Kitchen fitter that?

 

[littlespark]

Would kev the kitchen stop drilling when his drill starts making that ting ting ting sound as it bounces off any capping?

Nooooo…. Just keep going

 

[BiddeldyBwah]

Would kev the kitchen stop drilling when his drill starts making that ting ting ting sound as it bounces off any capping?

Nooooo…. Just keep going

I'm not up to date on domestic regs but i thought the RCD protection was what mattered? Still don't see much use for capping when it can just be drilled through and is RCD protected.

 

[pc1966]

I'm not up to date on domestic regs but i thought the RCD protection was what mattered? Still don't see much use for capping when it can just be drilled through and is RCD protected.

Yes, in most cases if the cable is not at least 50mm deep then RCD protection is needed (exceptions being the likes of SWA or cables to BS 8436 or IS 273 standards such as Flexishield).

Metal capping is not enough. If it were reliably earthed then it would allow safe disconnection without a RCD, but that is not likely. Traditional metal conduit would do, as it is designed to be the system CPC anyway.

The on-site guide suggests at least 3mm thick steel is needed for physical protection of cables. Even then I feel that it should be properly earthed as somebody could still penetrate it with a power tool and lack of care (or maybe nail-gun?) and having a large chunk of buried metal go live is I suspect worse. So my own choice would be plastic & RCD as most domestic circuits need that anyway.

 

[Deleted account]

A fifth option. It depends.
I did put no needed, but only if I am doing a light skim covering of my cables. If someone else is working around my cables after me and covering them I’d want to protect them From light tools and trowels.

its real easy to slice through insulation with a trowel. Ive done it myself.