EICR coding (C1,C2,C3,N/A)

[gazdkw82]

Just doing some mock exams for the upcoming 2391 course.

Confused on this question as I got it wrong.

Q. If a lighting circuit installed in metal conduit in a shop supplied from a TNS system had no RCD provided for fault protection but achieved disconnection times what would the outcome be on the schedule of inspections.

I put it as a C3. Improveme needed.

The answer has come back as N/A.

Can any explain this?

 

[Deleted member 26818]

Ok so it has to in an EARTHED conduit system. So conduit must be EARHED
Unless the conduit is sufficient to protection to prevent penestration by screw or nail. Then NO EARTH is required.
Now I would of said that all the metal conduit I have used would stop a screw or nail but is there any metal conduit that could be penertrated?
I

I have seen some very thin walled conduit whilst working on older installations. Sort of stuff you could literally squash with your fingers.
Nowadays I think light gauge conduit is something only found in places like the USA and Canada, or in the UK when it’s Stainless Steel.
The Galv steel conduit I use has a wall thickness of 3mm, though I understand it is possible to obtain a thickness of only 2mm.
Of course, there is flexible steel conduit (kopex), but that would only be suitable for use at a depth greater than 50mm, or within prescribed routes along with RCD protection.

Upon reflection, the question is probably based on the 18th edition, as it makes reference to ‘circuit’ and goes on to say the installation is non-domestic.
At present, the only circuits which require RCD protection, are those referenced in Part 7 Special locations.
Circuits of a location containing a bath or shower, etc.