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M

mike

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hi. ive been told than on the new regs that cables less than 50mm deep in the wall have to be rcd protected. does any know if this includes where you know there are cables like above switches. thanks
 
isn't it, if the cables arent 50mm deep, then mechinical protect it, or rcd it or both. An electrician may know they could be cables above the switch, but what about a home owner drilling through the wall to hang his pants on?
 
C

Cirrus

  • Thread Starter Thread Starter
  • #3
I've just seen the NIC DVD on this tomight and basically it says that if the cables are less than 50mm deep they must be RCD protected - UNLESS in trunking and then you do not have to place on an RCD
 
M

mike

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  • #4
really seems a bit over the top does any one konw what size rcd? hope its not 30ma
 
S

Shakey

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  • #6
Basically:

buried cable less than 50mm deep:-

within safe zone:30mA

within safe zone WITH earthed metallic protection (SWA, earthed conduit - NOT capping) - no RCd required (for cables)

Outside safe zone: 30mA WITH earthed metallic protection

Outside safe zone: must be earthed metallic covering (not allowed without)

Of course, if the cables feed sockets of 20A of less for use by ordrinary persons, or bathroom electrics, or equipment outside equipotnetial zone: RCD 30mA

UNLESS specifically labelled socket (ie Freezer only)

surface mounted CABLES do not need RCD but of course the circuit they are supplying may do (as above, bathrooms etc)

Obviously this will pretty much 'bin' the 100mA protection against fire RCD for TT's as well!
 
M

mike

  • Thread Starter Thread Starter
  • #7
thanks for that, but what do you mean by safe zone?
 
G

Grae79

  • Thread Starter Thread Starter
  • #8
like the twilight zone but less weird...

safe zones extend horizontally & vertically from wiring accessories (sockets/switches), the width of the zone relates to the length/width of the applicable accessory.

also have a safe zone of 150mm (6") at the top and corners of walls.
 
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M

mike

  • Thread Starter Thread Starter
  • #9
I see. if knowing the cables are not 50mm deep on a existing instalation, should i put in a rcd or just put in a rcbo on the circuit i workrd on?
 
C

Cirrus

  • Thread Starter Thread Starter
  • #10
Until June you don't have to do anything but when the 17th comes in then, you gotta do it.
 
M

mike

  • Thread Starter Thread Starter
  • #11
is there such a thing as a s type 30ma rcd if so would this acheive discrimination with a standard 30ma rcd. if so i suppose this could be used on a split board. dont fancy chasing all cables 50mm deep
 
G

Grae79

  • Thread Starter Thread Starter
  • #12
don't believe u can get 30mA S type RCD's
 
D

deano

  • Thread Starter Thread Starter
  • #13
S type RCD's start at 100mA appendix 3 of the 17th regs
 
D

DadofTwo

  • Thread Starter Thread Starter
  • #14
Until June you don't have to do anything but when the 17th comes in then, you gotta do it.
It doesn't have to be applied retrospectively does it? Basically, after June, if you go to do a job in a house and the cables of the existing wiring are buried less than 50mm (which of course they will be less) then do you need to RCD / RCBO protect that circuit even if you've not worked on that particular circuit?

I hope not! Can you imagine the problems that would cause!!!
 
S

Shakey

  • Thread Starter Thread Starter
  • #15
A 30mA s type would not trip within the required time, so would not comply

And the 17th is out now - you can use either.

And retrospective???? YES!!!!!

rather an answer here, i will start a new post, it will be of interest to a lot of people, i think. i will title it Retrospective application of the 17th edition
 
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