Mechanical protection

[Strima]

Epoxy resin between capping sheets and you'll have the poor mans version of Chobham armour... :lol:

 

[D Skelton]

I'm thinking of other scenarios as well biff, although you're right on the RCD front.

What about cables not in safe zones?

 

[Guest55]

stop being lazy and chase out the conduit drops.
we both know thats the real reason lol.

 

[Guest55]

What about cables not in safe zones?

option a -steel conduit
option b - swa
option c - steel conduit
:-D

 

[D Skelton]

stop being lazy and chase out the conduit drops.
we both know thats the real reason lol.

Ah, with regards to that, the block was waaaay too thin to chase, hence why I asked.

With regards to the other situation, I was thinking of CU changes that involve moving the CU thus rendering the cables buried in the wall out of their safe zone.

- - - Updated - - -

option b - swa

I never would, tis way too easy to penetrate with nails IMHO

Edit: I should add, these are hypothetical future situations that could potentially be made easier with steel capping than when I've been faced with these same situations in the past.

 

[Guest55]

Ah , no worries.
just make up the solutions as you go along , works for me. ;-)
as for swa , its a permitted type for rcd free circuits so dont discount it.

 

[Guest55]

is micc / pyro allowable for rcd free circuits ? hmm not sure , might be.

 

[D Skelton]

is micc / pyro allowable for rcd free circuits ? hmm not sure , might be.

I should hope not. Might be indestructable to a hammer and flames but it would be pretty easy to ram a nail thru it.

 

[Guest55]

I should hope not. Might be indestructable to a hammer and flames but it would be pretty easy to ram a nail thru it.

It doesnt have to , as with swa , neither will stop a nail but they are allowed because having a completely surrounding metallic covering guarantees to activate the circuit device on penetration.

 

[D Skelton]

It doesnt have to , as with swa , neither will stop a nail but they are allowed because having a completely surrounding metallic covering guarantees to activate the circuit device on penetration.

Not if the nail creates a path between earth and neutral

No in all seriousness, I totally get what you're saying and I'm aware of the reasons why SWA is considered suitable mechanical protection for a non-RCD protected circuit, however in my mind, I like to either protect a cable with an RCD, or I like to protect it from damage all together.

I'm not saying you're not right, I just don't like using SWA to protect buried cables, underground or in walls unless RCD protected also, this is purely down to personal preference

 

[Richard Burns]

is micc / pyro allowable for rcd free circuits ? hmm not sure , might be.

I raised this one on here a while ago and was told NO.
However the csa of the metallic sheath is suitable for use as a cpc, so I think, but should not say, that you could use this to omit RCD protection.
This is only my opinion and is not supported by others.

DS have you never touched earth and neutral together on an isolated circuit and tripped the RCD?

 

[madmac]

1 Layer of earthed metallic sheathing is all that is required to meet the old "EEBADS" method of protection for vulnerable cables.
As long as it's earthed, it provides EEB.
And as long as the the circuit is protected by the correct rating of fuse/circuit breaker then it is protected by ADS.
It also has a degree of mechanical protection for ordinary persons using tacs etc for fixing pictures, but if a drill is used or heavy nails etc then it will be pierced but that just brings us back to making sure it is "earthed".
It behaves in exactly the same way as an swa cable.
It's mentioned in the regs about conduit or swa or "earthed metallic protection".

 

[D Skelton]

DS have you never touched earth and neutral together on an isolated circuit and tripped the RCD?

I was talking about making a connection between neutral and earth on a non-RCD protected circuit. My point was that nothing would disconnect.

 

[Guest55]

I raised this one on here a while ago and was told NO.
However the csa of the metallic sheath is suitable for use as a cpc, so I think, but should not say, that you could use this to omit RCD protection.
This is only my opinion and is not supported by others.

i agree with that , and i've put that assessment into to practice this week.
tidying up wiring in grans house this week including re-jigging circuits in CU.
noticed that garage supply is actually pyro cable fed from the ring main mcb on the rcd side of split board.
Wanted to put garage on its own mcb ( plenty of spare ways ) but on the non-rcd side so freezer in garage doesnt trip the whole house if fault.
May not comply strictly speaking but did it anyway as its the most practical solution without spending big money.
i did a mental risk assessment and micc in ducting under block paving is unlikey to get damaged anytime soon

 

[D Skelton]

i agree with that , and i've put that assessment into to practice this week.
tidying up wiring in grans house this week including re-jigging circuits in CU.
noticed that garage supply is actually pyro cable fed from the ring main mcb on the rcd side of split board.
Wanted to put garage on its own mcb ( plenty of spare ways ) but on the non-rcd side so freezer in garage doesnt trip the whole house if fault.
May not comply strictly speaking but did it anyway as its the most practical solution without spending big money.
i did a mental risk assessment and micc in ducting under block paving is unlikey to get damaged anytime soon

It's all down to common sense most of the time aint it. Regs are regs.. but from time to time, we all realise that sections of the regs were never written by people living on this planet

Given that situation, I would have probably done the same thing, but I would still have used an RCBO.