Buried cables.

[pb8]

Your thoughts please lads and lasses. I'm assisting a local spark who's is fitting quite a few outside lights to a large kitchen/diner extention. When I've done them in the past I've always managed to get the cable run in line with a socket or switch so the cable is in the safe zone run that extends to both sides of a wall. But in this instance this will not be the case and I think we should run the cables in earthed metal conduit. Local sparky chum says not necessary as it's rcd protected? It will be buried less than 50mm deep by the way. Who's right??

 

[Mr Mark Sparks]

i am afraid to say he is
metal pipe would be great but total overkill

 

[glasgowspark]

yep, if a cable is buried less than 50mm deep and not in safe zones the use of a 30mA RCD is all that is required.

 

[lockhes]

so basically the safe zones dont really matter as long as there is an rcd present or have i read that wrong


personally id still try get it in safe zones

 

[m4tty]

I think the same as you mate but think it is good practice to keep in the safe zones but as you said does it matter as long as its covered by rcd??

 

[roukel01]

have a careful read of Reg 522.6.6, 522.6.7 & 522.6.8

I read it that if you are out of the permitted "Safe Zone" then you either need to use a cable with an earthed metalic covering OR metalic earthed Conduit, RCD protection is an ADDITIONAL requirement.

As mentioned, otherwise, there would be no need for the "Safe Zone"

 

[Mac]

Where a cable is buried in a wall or partition at a depth of less than 50mm on either side it must be sufficiently mechanically protected against penetration or Rcd protected and installed either horizontally within 150mm of the top of the wall or vertically within 150mm of the angle formed where two walls meet or run horizontally or vertically to an accessory, luminaire or ccu.522.6.6,522.6.7 This applies to a cable in a partition constructed using metallic parts other than fixings irrespective of the cable depth.522.6.8

 

[pb8]

Thanks for reply Mac but we're not in the safe zones you refer to, and thats the crux of my unease. Reading the other replies it would seem that as long as the cct. is rcd protected you can run cables where you like so the advice given in the osg and regs guides are only "nice to haves" and not essentials. Confusing and open to some dangerous practices I fear.
Thanks to all for your advice.

 

[roukel01]

Thanks for reply Mac but we're not in the safe zones you refer to, and thats the crux of my unease. Reading the other replies it would seem that as long as the cct. is rcd protected you can run cables where you like so the advice given in the osg and regs guides are only "nice to haves" and not essentials. Confusing and open to some dangerous practices I fear.
Thanks to all for your advice.

No you can't run cables anywhere, thats why we have safe zones. If you are within a safe zone then only and RCD is required for Additional protection. If you are OUT of the safe zone, then earthed metalic conduit or some kind of metalic sheathed cable should be used. RCD's are not allowed to be the sole means of protection.

There are now cables produced that have a metalic covering that allow you to run them outside of the safe zones.

 

[seanthereg]

I must agree with Rouke01 if you read the Regs 522.6.7 it states that if you install the cable in accordance with Reg 522.6.6 (v) which is within the Safe Zones and not complying with Regs 522.6.6 (i), (ii), (iii) or (iv) which is protection with a conduit, then additionl protection by means of an RCD should be provided while in the safe zones, and does not mean that if you put an RCD on you can place cables anywhere. That would be my interpretation.

 

[Spudnik]

There are now cables produced that have a metalic covering that allow you to run them outside of the safe zones.

Got a link?

The reason i ask is that there is a cable on the market that negates the need for ADDITIONAL protection from RCD's (cables buried less than 50mm etc), but not one that permits it to be installed out of safe zones.

 

[roukel01]

Dunno Jason, we're probably on about the same stuff. I assumed that because it has an earthed metalic sheath, it could be used outside of the zones

 

[Des 56]

Flexishield Cables

Is this what you are refering to perhaps

 

[roukel01]

Thats the stuff. I thought you could wap that stuff in anywhere!