High R1&R2 readings

[robert27207]

Hi all new to this so hopefully i can borrow some wisdom. I am currently carrying out a periodic inspection and testing of a commercial property. I have a db with 40 of the same circuits. The circuit is a 6mm radial to a junction box then a 2.5mm ring for 20 sockets. The circuit is wired in 6mm singles radial then 2.5mm singles in a ring. This is protected by a 40a RCBO 30ma type c. I am getting readings of around 1.20 for my R1 & R2 readings. This is the same for all these circuits. Connections are all tight inside sockets. How can i lower the readings to allow me to keep the same size of RCBO.

Thanks in advance.

 

[Pete999]

How are you testing the RFCs R1 and R2? sorry r1 and r2

 

[Guest77]

Regardless of the reason of the readings that is another topic, just to chuck a grenade in, and just to point out that 1.20 is fine for a RCBO if a zs, can't imagine it being much more for a R1+R2, because it is an RCD I suspect it will be fine, and anything under 100 ohms ZS wise, will keep the NICEIC happy, under 200 ohms the regs and 1667 will confirm it trips with in the required disconnection time lol, and why consider changing the size of the RCBO????

 

[Hellmooth]

If it's a ring to radial it isn't going to be straight forward end to end, how have you tested it?

 

[Leesparkykent]

Should it be on a 40A?

 

[robert27207]

I am testing R1 & r2 by connecting the earth and live at the db and testinbg on ohms at the sockets (furthest point). My Ze is 0.09 and my zs readings were roughly between 0.20 and 0.35. The RCBO's are tripping in time for x1 and x5. I may be wrong but i thought these R1 & r2 readings were high. Apologies if this is not the case.

 

[Guest77]

My point is if the ZS readings are that low 0.20-0.35 and is covered by RCD and it isn't tripping then so what, actually the circuit may have some cable length hence the reading, so zs = R1& R2 plus ZE

ZS-0.09
R1&R2 1.20
ZE= 0.35

????

 

[Simonslimline]

I am testing R1 & r2 by connecting the earth and live at the db and testinbg on ohms at the sockets (furthest point). My Ze is 0.09 and my zs readings were roughly between 0.20 and 0.35. The RCBO's are tripping in time for x1 and x5. I may be wrong but i thought these R1 & r2 readings were high. Apologies if this is not the case.

Have you taken any sockets off and tested on the terminals?

 

[Guest77]

How have you determined the ZE?

 

[Guest77]

Have you taken any sockets off and tested on the terminals?

Probably is a loose cable but I would like to see how the ZE was got?

 

[robert27207]

Yes i tested on socket terminals for my readings. Also checked connections were tight when i thought the readings were high. I think i may have thought the readings were high when it doesnt matter judging by the above posts.

 

[Guest77]

Yes i tested on socket terminals for my readings. Also checked connections were tight when i thought the readings were high. I think i may have thought the readings were high when it doesnt matter judging by the above posts.

Well it doesn't add up, however the ZE?

 

[robert27207]

My ze for the db was 0.09 tested with main earth disconnected. My zs for the circuits was varied between 0.20 to 0.35.

 

[robert27207]

I am getting similar readings for every circuit on the db.

 

[Simonslimline]

Edit...

Beaten to it.

 

[Guest77]

My ze for the db was 0.09 tested with main earth disconnected. My zs for the circuits was varied between 0.20 to 0.35.

To determin the ZE at the board, you would need to test the main earth and disconnect all other Earthing and Bonding conductors to avoid parallel path readings.

 

[Guest77]

he said the Ze is 0.09 mate.

yes and your point is?

 

[Simonslimline]

yes and your point is?

I was just reading what you wrote in an earlier post


ZS-0.09
R1&R2 1.20
ZE= 0.35


Was not sure if you had mixed up Zs with Ze reading thats all.

 

[Guest77]

I was just reading what you wrote in an earlier post


ZS-0.09
R1&R2 1.20
ZE= 0.35


Was not sure if you had mixed up Zs with Ze reading thats all.

LOL, yes I did mix up the readings chuckle, still interested in how he obtained the reading, although 0.09 sound good if it is a TNC-S system in any case.

 

[Leesparkykent]

do you have access to the junction box where the ring is connected to the 6mm cable? have you done a r1,rn and r2 continuity test of the RFC?