Changing direction of cable routing
- Thread starter Snark
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If that is the case, why is SWA, Flexishield and Pryo considered to be adequately protected against exactly the same risks in exactly the same location?
Do you really think that T/E with 1mm of steel between it and screws and nails is not as well protected as the cores of SWA, Flexishield or Pyro?
Do you really think that T/E with 1mm of steel between it and screws and nails is not as well protected as the cores of SWA, Flexishield or Pyro?
Because the conductors are totally surrounded by an earthed armour, foil or similar.
The 1mm steel plate may not be earthed.
The 1mm steel plate may not be earthed.
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Sorry, I'm reading and replying on a mobile and missed that part.
It all comes down to your interpretation of adequate mechanical strength and its ability to withstand penetration from nails, screws and suchlike.
It all comes down to your interpretation of adequate mechanical strength and its ability to withstand penetration from nails, screws and suchlike.
I think the pitiful protection allowed via flexishield is a useful guide - a thumb-powered drawing pin would probably defeat that...
I'm not saying my idea complies with the regulations without a judgement call, but 522.6.6 (iv) just says "sufficient" protection, and although the steel plate would not be incorporated in the cable it would provide much better protection in the direction in which there was a <50mm distance to the surface than any of the cables allowed in 522.6.6 (i).
To put it another way, assuming the cable is at least 50mm from the top of the skirting board, which is likely to be safer - a BS 8436 cable behind just 15-20mm of wood, or a PVC cable behind 1mm of earthed steel?
And what about the fact that PVC skirting trunking is sold?
I'm not saying my idea complies with the regulations without a judgement call, but 522.6.6 (iv) just says "sufficient" protection, and although the steel plate would not be incorporated in the cable it would provide much better protection in the direction in which there was a <50mm distance to the surface than any of the cables allowed in 522.6.6 (i).
To put it another way, assuming the cable is at least 50mm from the top of the skirting board, which is likely to be safer - a BS 8436 cable behind just 15-20mm of wood, or a PVC cable behind 1mm of earthed steel?
And what about the fact that PVC skirting trunking is sold?
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Interesting idea, Banal. I too have asked about using EARTHED steel capping over concealed cables to avoid RCDing them, but was shot down in flames. This is another one of those areas where the regs don't seem to make a great deal of sense:
Say you have a nice thick wall, on one side you chase a cable in >50mm - the regs say that's fine, no RCD protection required.
On the other side you chase in a cable <50mm and cover it with EARTHED steel capping (which you have shown meets the requirements for a CPC), but that is NOT OK to avoid RCDing, because the cable needs to be surrounded by the earthed metallic covering. Why?
Are they saying that someone might knock a superlong nail through from the other side? In which case the cable >50mm will get it too. Or in the reg writing world do they have nails that bend 180deg back on themselves?
The problem is that, traditionally, capping was regarded as offering no mechanical protection at all, being so thin.
But even that is thicker than the foil layer in a BS 8436 cable.
522.6.6 says that it is quite safe to run a cable anywhere you like, following any old route, at shallow depth, as long as it has a foil layer which provides b****r-all mechanical protection, but will ensure that anything penetrating the cable gets earthed on the way in.
Since earthed galvanised capping would perform at least as well as a bit of foil, and would ensure that anything penetrating the cable from any direction where it was <50mm from the surface got earthed on the way in I'm inclined to think that it should be acceptable.
But even that is thicker than the foil layer in a BS 8436 cable.
522.6.6 says that it is quite safe to run a cable anywhere you like, following any old route, at shallow depth, as long as it has a foil layer which provides b****r-all mechanical protection, but will ensure that anything penetrating the cable gets earthed on the way in.
Since earthed galvanised capping would perform at least as well as a bit of foil, and would ensure that anything penetrating the cable from any direction where it was <50mm from the surface got earthed on the way in I'm inclined to think that it should be acceptable.
You could have issues creating an accessible earthing point assuming you use a nut, bolt and eylet crimp. I'm not sure a pop rivet would make a suitable connection.
A pop rivet is applied using an appropriate compression tool.... 
I know but I'm not convinced that it'll hold an eylet crimp adequately. Granted, I've never tried it though....
pop rivets aren't applied using a compression tool..
the stems break off at differing tensions so there's no way of ensuring that the pop will always be at at least a given tension / pressure..
you have to select the proper pop for the thickness of material too..
the stems break off at differing tensions so there's no way of ensuring that the pop will always be at at least a given tension / pressure..
you have to select the proper pop for the thickness of material too..
As you were - see //www.diynot.com/forums/viewtopic.php?p=1630620#1630620 - capping is not acceptable.
Sorry.
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