Problem with zs test

[coatesykid]

TNS earthing arrangement. tested ZE 0.18 ohms tested ring final circuit R1+R2 = 0.35 ohms so that makes the calculated ZS for the ring 0.53 ohms, but when I test the zs with my 1 month old fluke multi the reading comes out at 7.4 ohms can anyone tell me why this is the case

 

[Guest 004]

how did you get your R1R2?
what are your continuity reading's for P-P, and E-E?

 

[topquark]

Have you reconnected your main earth after checking your Ze (maybe all you're seeing is any parallel paths when Zs testing your circuit).

 

[coatesykid]

got my r1 r2 by cross linking in cu and testing at sockets, P-P 0.3 ohms E-E 0.4 ohms aprox yes reconnect main earth

 

[Guest 004]

are you getting an high reading on all the sockets? or just one?

 

[coatesykid]

all sockets do u think the tester could be faulty

 

[coatesykid]

also first time i tested it was the same and they was a fault on the circuit so I re-wired the whole ring and put new socket fronts on

 

[Guest 004]

all sockets do u think the tester could be faulty

no because you got a low Ze reading. Trusting that you reconnected the earth at the DB, it sounds like further investigation is required. I would test your meter on another circuit, like cooker, and a lighting circuit, and see what readings you are getting there. Better still test in your home.

 

[Guest 004]

also first time i tested it was the same and they was a fault on the circuit so I re-wired the whole ring and put new socket fronts on

you have rewired the WHOLE ring? better get your meter checked then

 

[coatesykid]

how could reading be high on just 1 socket when all the sockets was less than 0.4 ohms r1 r2 test and the main earth is 0.18 ohms wouldn't that mean no mater the socket tested the zs reading should be no more than 1 ohm

 

[topquark]

Have you reconnected your main earth after checking your Ze (maybe all you're seeing is any parallel paths when Zs testing your circuit).

I'll try asking again, please confirm that you have reconnected your main earth.

 

[coatesykid]

sorry yes reconnected main earth

 

[Guest 004]

one socket could have been spured off, with a loose connection, also your earths could be twisted together thus giving a good continuity, but have come away from the socket terminal

 

[topquark]

How are you testing at the socket, are you using an adapter or directly at the terminals on the rear of the socket?

 

[coatesykid]

could a conductor have come lose between testing r1r2 and testing zs

im thinking of retesting the circuit from scratch as well has ze

 

[coatesykid]

sorry about the slow response its taking an age to refresh

 

[coatesykid]

no spurs and no twisted c.p.c i have just re-wired

 

[coatesykid]

yea im using an adapter

 

[topquark]

If it's with an old socket then try inserting and withdrawing it a few times (to clean the contacts). Before restarting your test take the socket off and test at the rear of the socket and let us know your findings. It could also be a faulty socket.