Max loop reading using RCD

[boballum]

How about this for a ponder.....
Lighting circuit wired in metal conduit buried in concrete, conduit used as the earth no seperate CPC

Replaced board reconnected conduit to main earth but readings are 45ohms obviously the conduit has broked down

My question is this, before RCD's on lighting circuits we would have rewired it but now it has an RCD with a max permissable loop of 1551ohms (roughly!) is this reading acceptable????

The circuit has class 1&2 equipment on it

 

[IQ Electrical]

The metal conduit is still an exposed conductive part containing live conductors and has therefore still to be properly constructed and provide good continuity throughout it's run and be earthed.

 

[boballum]

That I understand but this conduit system is totally buried in concrete??

 

[Farmelectrics]

personally i would recomend pulling earthing conductors in peace of mind

 

[Deleted member 9648]

As above....regardless of the measured Zs the R2 must be an acceptably low value....pull a cpc in and earth the conduit at both ends.

 

[Johno]

I agree, obviously it's not what you or the customer want to hear, but it does want sorting.

I hate that part of the job, breaking bad news to customers, you worry that they will think you're trying it on, but at the end of the day you have got to cover your arse!