Zs on ring issue.

[Gc1971]

Hi all 

I've a ring which passes all the tests upto Zs whereby it trips out. My IR test would surely show any possivle leakage? A Martindale shows the circuit as fine too, but put any load on it and it trips. 

Can anyone help me isolate the problem? 

Thanks 

 

[SPECIAL LOCATION]

What trips?   Wire fuse, Cartridge Fuse, MCB, RCD, RCBO..???

What exactly do you mean by passes all tests up to Zs?

Surely dead test which would give you R1+R2 values..

which could then be added to you Ze would confirm if Zs is within max permissible values..?

:C

Do you mean your meter Zs function trips the RCD?

 

[kerching]

What's tester are you using?

why do,you feel the need to test the circuit?

did It just start tripping after previously working correctly?

have you done any work on the circuit and made/altered connections in the distribution board?

at first sight, and it seems difficult to see from here, it's fairly obvious what the fault may be.    But I will,await your response to the above questions

And what setting have you got the meter set to?

do you understand how RCDs RCBOs ( I doubt if it is RCBOs, but anyway....) function?

what sort of board is it?non compliant dual,RCD jobbie?

 

[kerching]

Holds on "no load"

trips on "load"

 

[Gc1971]

Hi, yes the rcd trips. The circuit has had a change of socket fronts. It's not a rcbo and the meter is set to non trip, thanks!

 

[Murdoch]

IR readings?

 

[Gc1971]

Sorry, I meant to say it's a megger 1552.

Ir readings are >299 on live-CPC, live-neurral and neutral-CPC too.

 

[kerching]

Have you done ANY work inside the board?

What are R1 +. R2.      And r1 + r2 values?

 

[Gc1971]

Hi all, sorry for delay I'm on kids tea duty being Mothers day. I did pretty well apart from the veg apparently..

So this was first fixed ages ago and I'm not experienced in testing (can u tell haha).

I've got some figs for you, 

r1 0.21

rn 0.21

r2 0.33 so all looking ok

R1-R2 0.22 at board and 0.23 at sockets (they're in the same room) so still looking ok

Insulation Resistance was all clear (<299) on L-N, L-CPC and N-CPC Still looking good 

Ze was 0.5, but Zs just tripped the rcd. It's a older plastic split load job and it trips both sides.

Been ages since I did my course (16th) but i think its gonna trip both as it's a neutral shared and it's got an imbalance on l-n? Is that right?

Thanks again everyone 

Gc

 

[kerching]

Mmmmm

split/borrowed neutral off different bus bars possibly

those R and r values don't equate if it's a true ring

 

[Sidney]

IR done with accessories fitted?

 

[Gc1971]

Mmmmm

split/borrowed neutral off different bus bars possibly

those R and r values don't equate if it's a true ring

Mate that's it isn't it. Shoulda actually put my brain back in when I said split board and shared neutrals. Blimey I've been such a div.. I put the neutrals into the wrong side!

Thanks everyone for your help. Its sorted now, got a Zs of 63 so well under my table value. Have a lovely evening. I can relax now and have my beer.

 

[kerching]

Just remember     'None of us ' knows as much as 'all of us!'

been there done that

giveaway was when you said it tripped when on load

and you are one of the few that ever get back to us after the problem has been fixed!.....respect

 

[Gc1971]

Too true. I was just saying to my wife how amazing the internet can be. It's so refreshing when complete strangers put effort into helping you out, it reminds you the human race is still decent at heart.

Thanks to everyone again. You're great!

 

[kerching]

Hang around, it's quite good on here mostly!   There are some wazzockS but you soon work out who the oxygen thieves are

 

[Gc1971]

Will do mate. Thinking of getting my 18th and going solo actually. I did a little update to get my 17th but I dont think you can do that for a 17th to 18th certificate anymore. I'll do an online jobbie after work I think.