Addition to ring main circuit

bulby · Nov 23, 2011

Hi, if im adding to a ring main circuit on a minor works cert do i have to change the bs3036 fuse to a rcd protection. Adding to the ring main entails coming off back of excisting socket creating a spur having cable through wall less than 50mm deep.

Can you please advise

IQ Electrical · Nov 23, 2011

bulby said:
Hi, if im adding to a ring main circuit on a minor works cert do i have to change the bs3036 fuse to a rcd protection. Adding to the ring main entails coming off back of excisting socket creating a spur having cable through wall less than 50mm deep.

Can you please advise

Have a read of this: Alterations and additions in domestic and similar premises : Electrical Safety Council

bulby · Nov 23, 2011

IQ Electrical said:
Have a read of this: Alterations and additions in domestic and similar premises : Electrical Safety Council

Yes i have now thanks, this unit is for a charger for a stairlift, so it is for a specific piece of equipment, it says it doesnt need specific rcd protection but it does say the extended part of the circuit does ? can you clarify ? I am not undertsanding this very well , does it mean instead of a fuse spur i need to fit an rcd fuse spur ?

telectrix · Nov 23, 2011

it's the cable buried in wall less than 50mm deep that needs RCD.

stuart569 · Nov 23, 2011

522.6.6 - Cables Installed in a Wall or Partition. This says that: 'A cable installed in a wall or partition at a depth of less than 50mm from the surface of the wall or partition shall':
Incorporate an earthed metallic covering which complies with the requirements for a protective conductor of the circuit concerned, the cable complying with BS 5467, BS 6346, BS 6724, BS 7846, BS EN 60702-1 or BS 8436, or;

be enclosed in earthed conduit, or;
be enclosed in earthed trunking or ducting, or;
be mechanically protected against damage, sufficient to prevent penetration of the cable by nails, screws and the like, or;
be installed in the traditional 'safe zones' - 150mm from the top of the wall or partition or within 150mm of an angle formed by two adjoining walls/partitions, and horizontally or vertically to any point, accessory and switchgear.

bulby · Nov 23, 2011

stuart569 said:
522.6.6 - Cables Installed in a Wall or Partition. This says that: 'A cable installed in a wall or partition at a depth of less than 50mm from the surface of the wall or partition shall':
Incorporate an earthed metallic covering which complies with the requirements for a protective conductor of the circuit concerned, the cable complying with BS 5467, BS 6346, BS 6724, BS 7846, BS EN 60702-1 or BS 8436, or;

be enclosed in earthed conduit, or;

be enclosed in earthed trunking or ducting, or;

be mechanically protected against damage, sufficient to prevent penetration of the cable by nails, screws and the like, or;

be installed in the traditional 'safe zones' - 150mm from the top of the wall or partition or within 150mm of an angle formed by two adjoining walls/partitions, and horizontally or vertically to any point, accessory and switchgear.

Hi ive just read this on the Electrical safety council website, i know what your saying but what interpretaion do you get from this :
Q4. A switched, fused 13 A connection unit is to be added to an existing circuit. The work is not being carried out in a special location and the existing circuit has no RCD protection. The incoming services are bonded and the new switched fused connection unit is to be flush mounted 150 mm horizontally from an existing socket, and connected with wiring concealed in the wall. What is the reasonably expected for the installer to do to comply with the 17th Edition?
The connection unit does not require additional protection by RCD, though at least the extended part of the existing circuit will need to be suitably protected (by RCD or other means).

Regulation number(s)

522.6.101 to 522.6.103

stuart569 · Nov 23, 2011

I'm bored lol.Just bloomin RCD it

WDMDL · Nov 23, 2011

The SFCU is for a specific piece of equipment, st that's why IT doesn't need RCD protection.

BUT the new bit of cable is buried in the wall. So THE CABLE must be RCD protected. Which inherently makes the SFCU RCD protected!

You could change the existing socket to an RCD fused conn unit, then put a socket adjacent if you still need one there, and connect your new addition to the RCD fused conn unit.
Maybe if the existing socket is a double, change to a DUAL back box...

There's always a way!

Simon.