Amd 3 and plastic wall plugs

[SimonH2]

Do I take it that no-one thinks that what I thought might be the reason (that the buckle clips could conceivably become 'live') had anything to do with their 'vanishing'?

Personally I don't think that's a reason - only the economics of installation.

 

[JohnW2]

Personally I don't think that's a reason - only the economics of installation.

Fair enough - as I said, it was just what occured to me at the time. There was quite a long period during which both buckle clips and plastic clips were available and then, seemingly fairly suddenly, the former suddenly appeared to have vanished. At the time, I therefore suspected that some regulation had 'banned' them (probably because of the 'becoming live' risk), but I now know that that was not the case.

The risk I was considering is obviously a very small one, and one which would only result in something very small 'becoming live' even if it did happen - but, mind you, people sometimes get concerned about the heads of accessory faceplate screws, which are even smaller! I must say that, irrational though it may be, when I have put, say, T+E cable in metal conduit for mechanical protection (as in my garage), it probably would not have occurred to me to 'disregard that risk' and therefore not bother about earthing the conduit.

Kind Regards, John

 

[ban-all-sheds]

The LINIAN FIRE CLIP looks like the way forward for securing cables.

AFAIR, that's the first time I've seen this:

And with the disclaimer that I've not looked at the product at all, how is it superior to not having non-buried cables?

 

[ban-all-sheds]

I must say that, irrational though it may be, when I have put, say, T+E cable in metal conduit for mechanical protection (as in my garage), it probably would not have occurred to me to 'disregard that risk' and therefore not bother about earthing the conduit.

I would say that while the the original decision to use conduit might be irrational, the decision to earth it falls under the heading of "doing it properly".

 

[JohnW2]

I don't see anything irrational about putting T+E in metal conduit to protect it from mechanical damage in a potentially 'hostile' environment. Earthing it is what I would do (and have done) but I don't see any sense in which that is required to 'do it properly' - after all, we don't (and can't) earth every piece of metal with which an insulated-and-sheathed cable might come into contact.

 

[333rocky333]

I think i mentioned it here before and it was dismissed as nonsense. I recall, possibly the NICEIC once published an article in the PE magazine that T +E does not conform in pipe, as all 3 conductors of a circuit in Tube or Trunking must be the same size, and the formula for the reduced earth csa to be allowed, does not apply, though I have never found any reg to confirm it.

 

[333rocky333]

AFAIR, that's the first time I've seen this:

View attachment 151087

And with the disclaimer that I've not looked at the product at all, how is it superior to not having non-buried cables?

It cannot be superior.
Most of them look like they would be rubbish unless you have a good wall to start with, i am sure we have all at some time struggled with Wallplugs not gripping in crap walls, I don't see how these things with small sharp teeth will not suffer the same fate when the fixing wall if made of certain materials gets up to temperature, surely there only ideal in concrete or substantial brick, at the end of the day its only the installer at the time that can determine if it has fixed substantially.

 

[JohnW2]

I think i mentioned it here before and it was dismissed as nonsense. I recall, possibly the NICEIC once published an article in the PE magazine that T +E does not conform in pipe, as all 3 conductors of a circuit in Tube or Trunking must be the same size, and the formula for the reduced earth csa to be allowed, does not apply, though I have never found any reg to confirm it.

That sounds very odd, and I'm pretty certain that BS7671 (17th or 18th) doesn't say anything like that. I'm not even sure I've seen anything like that (as a reg) even in relation to singles, although I presume the practice then is to use conductors all of the CSA.

What BS7671 does say about CPCs (by implication, in any situation) is that although the lazy can use Table 54.7 (and therefore end up with the CPC having the same CSA as the line conductor,at least for conductors up to 16mm²), it is also permissible (better?) to utilise an adiabatic calculation, which will often end up indicating that a CPC smaller than the line conductor is acceptable - and that calculation takes no account of what CSA the line conductor may have.

At first sight, it seems to make little sense that the requirements for the required CSA of a CPC should vary according to how the cable is routed.

If there were a reg saying that it is not acceptable to put T+E into some sort of tube/trunking to protect it from mechanical damage in a 'hostile environment', then I think I would have to say that the regs were being more daft than usual! Indeed, there are regs requiring cables to be protected from mechanical and environmental damage - if that can't be done (with T+E) by putting it 'inside/behind something', how on earth can one comply with that reg?

Kind Regards, John

 

[SimonH2]

I recall, possibly the NICEIC once published an article in the PE magazine that T +E does not conform in pipe, as all 3 conductors of a circuit in Tube or Trunking must be the same size, and the formula for the reduced earth csa to be allowed, does not apply, though I have never found any reg to confirm it.

If it were true, then there would be a heck of a lot of installations that don't meet regs - T&E in conduit or trunking is not exactly rare !
I cannot see any logic to why the CSA calculations would be be different for what is just a different installation method. I wonder if someone got confused between different aspects ...
I'm assuming that the rules for singles (and earth CSA) in conduit or trunking are different to those for T&E ? Perhaps someone saw that (say) 2.5mm² singles in conduit need a 2.5mm² earth - and extrapolated that to not allowing the reduced CSA earth in T&E ?

 

[mattylad]

They look crap to me.
IMO the plastic from this crappy plastic conduit will simply melt around them.

I think the regs need to ensure that everything is piped in 100% steel conduits and trunks.

mwahahaha!

 

[333rocky333]

That sounds very odd, and I'm pretty certain that BS7671 (17th or 18th) doesn't say anything like that. I'm not even sure I've seen anything like that (as a reg) even in relation to singles, although I presume the practice then is to use conductors all of the CSA.

What BS7671 does say about CPCs (by implication, in any situation) is that although the lazy can use Table 54.7 (and therefore end up with the CPC having the same CSA as the line conductor,at least for conductors up to 16mm²), it is also permissible (better?) to utilise an adiabatic calculation, which will often end up indicating that a CPC smaller than the line conductor is acceptable - and that calculation takes no account of what CSA the line conductor may have.

At first sight, it seems to make little sense that the requirements for the required CSA of a CPC should vary according to how the cable is routed.

If there were a reg saying that it is not acceptable to put T+E into some sort of tube/trunking to protect it from mechanical damage in a 'hostile environment', then I think I would have to say that the regs were being more daft than usual! Indeed, there are regs requiring cables to be protected from mechanical and environmental damage - if that can't be done (with T+E) by putting it 'inside/behind something', how on earth can one comply with that reg?

Kind Regards, John

I so which i could find the article ,it was some time back, although to me anyway it seems right to use same size in singles and i have only encountered smaller earths twice, the article even condoned using say a 4" trunking to enclose the T+E cables into the top of a DB.
Afaik no other cable types use a smaller earth and the article was focused on T +E, i wonder if they were getting mixed up with grouping facters or something

 

[securespark]

And with the disclaimer that I've not looked at the product at all, how is it superior to not having non-buried cables?

I'm not sure where you're going as you believe that buried cables (at least in my example) can quickly become unburied in a fire.

 

[JohnW2]

I so which i could find the article ,it was some time back, although to me anyway it seems right to use same size in singles and i have only encountered smaller earths twice ...

Indeed, as I said, although I'm not at all convinced that there is a reg which requires it, my understanding is that standard practice is to have CPC singles as the same CSA as the L&N. Mind you, the whole discussion would become more complicated, and potentially a bit silly, if a conduit/trunking contained multiple singles relating to different circuits with different CSAs!

If, as is the case, the 'reduced CSA' CPC of T+E is deemed to be acceptable with any other installation method, I really can't see how/why that couyld cease to be the case if it was within conduit or trunking!

Kind Regards, John

 

[SimonH2]

Back to the original topic ...
I suddenly remembered that I've seen (and possibly used ?) in the past a metal equivalent to the plastic wall plug. And on checking, I see that there are indeed such things still available. So in that respect, if the question is whether the plastic plug in the wall is a weak spot in a fire, then metal ones are available and therefore don't need any changes in working practices to use.

 

[SUNRAY]

Back to the original topic ...
I suddenly remembered that I've seen (and possibly used ?) in the past a metal equivalent to the plastic wall plug. And on checking, I see that there are indeed such things still available. So in that respect, if the question is whether the plastic plug in the wall is a weak spot in a fire, then metal ones are available and therefore don't need any changes in working practices to use.

Would they be Alex Plugs? post#12