Consumer's Tails > 3 metres - RCD or not RCD

[Timotei]

I have been going over this for some time, and every time I think I have it sorted I read something else which sows doubt in my mind again!

TT system.

CU to be replaced and moved to new location as not enough room where currently sited.

New location will result in tails being approx 5m in length and running short distance under floorboards.

Current set up would be DNO Fuse > Meter > DP Isolator > CU with 100mA TD RCD and 2 x 30mA RCD.

To reach new location I had planned DNO Fuse > Meter > DP Isolator > Switch Fuse > 25mm SWA > CU with 100mA TD RCD and 2 x 30mA RCD.

Do I need up front RCD protection of these "extended tails"?

I have read 522.6.204 (iv) to mean it is not required.

Would appreciate thoughts of those wiser than myself to stop me going round in circles.

Timotei

 

[westward10]

What is providing fault protection to this new supply.

 

[Wilko]

My thought would be to move the 100mA S into the upfront DP isolator position. Just confirm it's of a type that is approved for use as DP isolator (Wylex make a nice one, for example).

 

[Darkwood]

I would fit a 100mA DP rcd with adjoining overload protection next to the cutout.
I would then wire DB supply using a method like SWA etc to ensure the need to cover at 30mA is not required and then supply a standard main switched board with 30mA cover where required.

Result is, all sides of your butt is covered regarding the regs and installation safety.

 

[Timotei]

Thanks, bit of a "can't see the wood for the trees" - upfront RCD it is then!

Didn't seem right without it, but kept coming back to that reg and then running round in ever decreasing circles!

Appreciate your help.

Timotei

 

[Deleted member 26818]

You will need to provide fault protection for the SWA.

 

[NDG Elecs]

A Wylex 110m would do the job nicely. Just swap over the DP iso for your S RCD, as per Wilkos post really.

Also it has plenty of room for your SWA glanding.