PIR issues encountered.......assistance please

[Octopus]

Hi,

Been doing a PIR today and the first circuit I tested I could tell that things were going to be difficult:

1. The ring circuit had no continuity end to end on, on live, neutral or CPC. After much investigation it would see that 1 short leg went to a 2 gang socket, and the other leg appears to be a long radial (both connected into a 32A MCB).

On trying to understand the "radial/ring" I did earth loop tests on all sockets and got the following readings (the list is in the "logical" order but who knows what people over the years have got up to) its split over 2 floors so D = down and U = upstairs:

D6 2.29
D7 2.19
D8 1.71
D9 1.14 (this is the one on its own)
D10 1.57
D11 1.09
D12 1.18
D13 1.21
D14 1.51
D15 1.42
D16 1.38
D17 1.38

U7 1.43
U8 1.27
U9 1.34
U12 1.88
U13 1.92
U14 2.01

Any thoughts on how best to confirm that the radial is a radial, I'm suspicious that its a radial with bits added at different points like a mind map!

Also the RCD (fitted between the DNO and the main CU) wouldn't trip in 30ms. Its a TT system by the way.

Couldn't see any main bonding from main CU to the earth electrode - a continuity check revealed a 1.09 ohms reading - scary!

Gentlemen - ideas and thoughts would be useful.

Thanks.

 

[Sparky Ninja]

To determine the radial just locate the final socket.
TT system, I believe the RCD wants to operate within 0.2 seconds
Is that 1.09 ohms continuity from electrode to CU?


Out of interest, what Ze did you measure?

 

[Deleted member 9648]

I think you are getting in too deep,if the circuit has a 32a protective device and end to end readings confirm it is not a ring,slap a code 2 on it..end of story.It is up to the recipient of the PIR to decide whether they want to sort the problem.Your job as inspector is simply to identify that there is a problem.
As above....a 30ma rcd should trip in 200ms @1x...and 40ms@5x.
There is no main bonding to an electrode,that would be the main earthing lead,I assume that is what you mean.....as above,what is the Ze reading?

 

[IQ Electrical]

I'll be honest here, you refer to main bonding instead of an earth conductor, 30ms trip times on an rcd, are you competent to be carrying out a periodic inspection?

If the electrode reading (Ra) is 1.09 Ohms then it's better than any I've ever seen and I've seen a few!

If the rcd is a BS4293 then the max trip times are 200ms on 1X and 40ms on 5X

If the rcd is a BS61009/61008 then the max trip times are 300ms on 5X and 40ms on 5X

Was the rcd time delayed ? (an 's' symbol in a square box on the rcd)