Mechanical protection

[D Skelton]

Just out of interest, how many steel capping lengths stacked on top of each other would you consider to be suitable to provide mechanical protection to switch drops on non-RCD protected lighting circuits?

I've always been lead to believe that 3mm of steel is thick enough to be defined as mechanical protection against screws and nails which by my measurement would make it about 5-6 steel capping lengths stacked. Would you stack more or less? Would you even consider it suitable?

And before you mention it, lets say for example that steel conduit is out of the question.

Debate...

 

[trev]

As it's layered perhaps some could be surplus to requirements. A penetrating object would have it's velocity reduced by the first layer, then the second slows it some more etc etc. Wouldn't like to try it though

 

[Des 56]

I suppose you could judge "how many" whilst fitting
If you can easily bang your fixing nail through the sheathing you may need more :smile5:

 

[Silly Sausage]

I've always been lead to believe that 3mm of steel is thick enough to be defined as mechanical protection against screws and nails which by my measurement would make it about 5-6 steel capping lengths stacked.

Not with my Hilti used in anger! :smiley2:

 

[D Skelton]

I suppose you could judge "how many" whilst fitting
If you can easily bang your fixing nail through the sheathing you may need more :smile5:

Fixing nail??? Steel capping??? lol

No, I would probably drill the stack me thinks and combine with screws and plugs

 

[Des 56]

Fixing nail??? Steel capping??? lol

No, I would probably drill the stack me thinks and combine with screws and plugs

Ah,you are now copying my usual method,but we need to use capping nails for the considered opinion of "how many"
Bringing drills and such to the issue would be infecting the experiment with high technology, that would render the result invalid

 

[Richard Burns]

Take a piece of steel conduit and cut in half lengthways and drop over the cable, fix with pipe clips, sorted!!

 

[Silly Sausage]

.......................

 

[Strima]

Take a piece of steel conduit and cut in half lengthways and drop over the cable, fix with pipe clips, sorted!!

Plenty of lube and good blades then... Sounds like a good night out in Liverpool.

 

[Guest55]

How can steel conduit be out of the question , but 6 layers of capping is a considered alternative ?
Fit as many as you want lol , bs7671 still wont recognise it as proper mech protection ;-)
its not just thickness either , conduit steel is considerbly harder than capping tin-foil.

 

[Guest55]

Take a piece of steel conduit and cut in half lengthways and drop over the cable, fix with pipe clips, sorted!!

good luck with that :-/

 

[D Skelton]

How can steel conduit be out of the question

Coz it is

but 6 layers of capping is a considered alternative

6 layers of capping would only be about half the thickness (overall width wise) of the diameter of 20mm steel conduit. If mounted on a wall, it is just as thick as 1/2" plasterboard and can easily be plastered over. Steel conduit would protrude too much to plaster over.

bs7671 still wont recognise it a proper mech protection ;-)

Correct me if I'm wrong but as far as I'm aware, BS7671 has no guidance for what can and can't be considered mechanical protection, only that mechanical protection must be suitable for each individual situation.

its not just thickness either , conduit steel is considerbly harder than capping tin-foil.

Hence why I said 6 layers. I've used 3mm steel plate to protect cables before and you aint never getting a nail through that unless you're using a Paslode! Then again, with a Paslode you could quite easily penetrate galv conuit as well I just wondered if enough capping was stacked together to an overall thickness of 3mm, surely that wold be the same as 3mm plate steel anyway?

 

[Guest55]

you're dreaming.
;-)

 

[D Skelton]

Dreaming of a solution to a problem that doesn't involve steel plate

 

[Guest55]

and youre wrong about bs7671 guidance on mech protection.
dont want rcd's ? then its EARTHED steel conduit or swa. thats your lot.
gonna be earthing your 6 layers of capping then ?
thought not lol.