Safe zones question

[Blue Fox]

Hello all,

Just a quick question about safe zones, the safe zone is horizintally or vertically from any accesory and I believe its on both sides of the wall, does this include external walls. The reason I ask is looking at a cable route for an extension to a kitchen, the extension is on the side of the house and am going to break into the existing ring main, fortunatly in the original kitchen there is a socket on the wall where I can drill straight through what was the external wall and into the extension, but the customer doesn't want any sockets on this wall only on the opposite wall internally. Its the same for the return there is a socket at the other end of the current kitchen where I can join back into the ring (the 2 sockets are next to each other in the ring so will just be extending a ring), but is this covered by the safe zones as it is through a double brick formally external wall? Additionally to this they also want an outside socket for the lawn mower if I fit this to the outside of the wall of the extension can I then run the cable internally and poke it through straight into the socket or is this not covered by safe zones as its an external wall?

 

[Robojin]

Hello all,but is this covered by the safe zones as it is through a double brick formally external wall? Additionally to this they also want an outside socket for the lawn mower if I fit this to the outside of the wall of the extension can I then run the cable internally and poke it through straight into the socket or is this not covered by safe zones as its an external wall?

So I presume you intend adding this as a spur to the ring?, I'll ask the obvious covered by an RCD?, external sockets with appropriate IP rating? and not forgetting any hole should be angled to prevent water penetration into the cavity and beyond, and the hazard of drilling near to installed cables.

As I read the OSG Safe zones refer to internal walls, but I'd suggest you read through 522.6.6 for you own peace of mind

 

[Blue Fox]

Thanks for the reply, no its not a spur, the socket that I will be breaking into the ring at connects straight to the socket I will be rejoining at so am just going to disconnect the cable between the 2 so extending the ring. I thought it was internal walls but wasn't sure so if its an internal wall how does the formally external wall which is now an internal wall come into this do I now just class that is an internal wall and can run cables the other side of it in line with an existing socket. RCD etc not a problem - doing c/u change at same time.

 

[Andy™]

'Safe zone' only applies to the side of the wall that the accessory is on

 

[NozSpark]

'Safe zone' only applies to the side of the wall that the accessory is on

unless the wall is <100mm thick!!

 

[green-hornet]

What you need to do is a risk assesment, rules and regulations are there as a guide to which you can work to, remember any deviation is not a contradiction of the rules.

A safe zone "will" extend to the reverse of a wall if the cable is less than 50mm from the surface, however this does not extend to the outside wall because of the structure of a cavity renders any cable un-likely to be within 50mm from the surface of that wall.

Drilling through the wall to the new extention means you are now on an "internal wall" so will need to be in a safe zone, however read the 17'th regs again and low and behold if RCD protected you are allowed to "deviate" from regulations.

 

[Oracle]

eh?

I'm with nozspark, i thought the 100mm rule applies - or is this just internal?

 

[green-hornet]

A zone formed on one side of a partition wall of 100mm or less thickness extends to the reverse side only if the location of the accessory can be determined from the reverse side.

 

[Blue Fox]

Have now re-read the reg in the big red book as was taking it out of the OSG, the 100mm rule does apply if the location of the point or accesory can be detirmined from the other side, so in my case going through a former outside wall that won't be a safe zone, will have to look into another route now then. The RCD protection only applies if the cable is less than 50mm in the wall AND meets the 150mm rule for corners or safe zone vertically and horizontally from accesory.

Thanks for your comments

 

[NozSpark]

A zone formed on one side of a partition wall of 100mm or less thickness extends to the reverse side only if the location of the accessory can be determined from the reverse side.

Exctly what I was saying,,,, but is contrary to what you said in post #7

 

[springcrocus]

I would suggest that "safe zones" are there for the benefit of the sensibly-minded. If a socket is flush-mounted in a wall, how does the cable get to it? Logically, up, down or from the sides in a straight line.

If you are on the other side of the wall, there is no socket visible so no reason to assume there are any buried cables in the wall you are about to drill into.

My take on this is that safe zones are ONLY on the side of the wall that you can see an outlet.

Therefore, your method is unacceptable unless you put a blanking plate on the other side to warn that there are buried cables.

Hope this makes sense?

 

[green-hornet]

Exctly what I was saying,,,, but is contrary to what you said in post #7

I will try to explain.

When you bury a cable in a wall and connect a switch or socket you have used a safe zone this safe zone is permitted because the accessory is visible.

Now lets say that the wall is only 50mm thick and you have buried the cable 20mm. On your side of the wall its fine you are in a precribed safe zone.

However the reverse side is NOT classed as a safe zone because there are no accessories to be seen. It CAN be classed as a safe zone however if the accesory can be determined from the other side of the wall.

When you create a safe zone it applies to that side only, you do not create a safe zone on the other side of the wall, unless the socket or switch can be determined.

I hope I have explained it clearly.

 

[batty]

I don't think any zone is safe. DNO have stopped installing incoming cables up cavity as people have been killed drilling through main cable. The world is full of idiots so be warned.

Batty

 

[NozSpark]

I think that the <100mm rule is really meant for paramount partition walls where you have a doorway that allows you to look at both sides...