RCD Protection of tails to flat

[Badged01]

1st floor flat on PME supply. Service head on lower floor below G/F flat. Tails to 1/F flat some 10m away protected by switched fuse after meter. Cant see run of tails but 99.99% sure they are buried in the wall as no conduit/trunking evident and they also go through the communal staircase area.

Questions:
1) Should these tails to the flat be RCD protected from the switched fuse? and
2) Should this RCD be time delayed to discriminate with the RCD's in the flat consumer unit?

I believe they should be RCD protected and time delayed to meet regs but would be interested to know if there is an alternative rationale for why they shouldnt.

 

[somersetsparks]

No the tails were already there, probably been in some 20+ yrs!

- - - Updated - - -

No the tails were already there, probably been in some 20+ yrs!

Well I would leave them be then, if you put a 30mA rcd on them you are IMO, worsening the installation

 

[Spazz]

I am installing these tails - the issue I have is that the landlord wont think about double layering the stud wall increasing the gap between the plasterboards to over 150mm. I remeasured it yesterday and the partitions are 75mm plus 7mm for each plasterboard (80mm (ish)) So only 30-40mm to the tails.

The other flats are easier because they are installed behind plasterboard and against a solid wall giving me over 50mm of protection.

The flat in question is on 1 level and one floor up - and covered by emergency lighting and on its own CU so that wont be effected if the RCD trips. I will have to put a note on the CU to check other CU in electric cupboard.

Thanks again.

 

[tony mc]

If you are responsible for the install then IMO I would be looking at ways of protecting the tails and getting away from a single RCD at the front end.

I would imagine a dual RCD 17th edition board is fitted in this flat and if so the RCD's are not going to be effectivein relation to division of installation.

It will be a lottery as to which RCD trips if a fault develops'

Even with emergency lighting in place IMO I would try and sort this issue out before the tails are installed as it could be a nightmare for a owner occupier of the flat in the future and it is a departure from the regs !

 

[Richard Burns]

I am installing these tails - the issue I have is that the landlord wont think about double layering the stud wall increasing the gap between the plasterboards to over 150mm. I remeasured it yesterday and the partitions are 75mm plus 7mm for each plasterboard (80mm (ish)) So only 30-40mm to the tails.

The other flats are easier because they are installed behind plasterboard and against a solid wall giving me over 50mm of protection.

The flat in question is on 1 level and one floor up - and covered by emergency lighting and on its own CU so that wont be effected if the RCD trips. I will have to put a note on the CU to check other CU in electric cupboard.

Thanks again.

As you are installing the tails then you need to use SWA to avoid the requirement for an RCD at the supply, then you can wire as normal thereafter. The cost for 3 core SWA versus 2 x tails plus earth is going to be minimal over one floor.