Zs tripping rcd

[jord35davies]

hi guys,
Hoping for a little advice.
Been working on a property this week and have been having trouble getting zs readings as it trips the rcd on a 17th edition cu.
Property is pme. I've tried testing idividual circuits one by one and completely disconnecting all the others but it still trips. It doesn't seem to matter what circuit is tested it trips on every one.
I've checked absolutely everything and all tests leading up are fine. Zs tests however trip rcd.
I've done a ramp test on rcd to check that and it's fine.
I've got a feeling it's a Dno issue but they have now confirmed there are no faults on the line. Anyone had similar issues.
Thanks in advance

 

[jord35davies]

Try clamping the tails to see what leakage is there before you test as even on No Trip your still injecting 15mA into the cct so you may have a leakage which puts the RCD above its Ramp value just a thought!

Thanks Tony at last some decent advice. Thank you

 

[Octopus]

It doesn't trip the 2 rcds. It trips the rcd to which that circuit I'm testin is covered by. Make sense??

Let me rephrase the question.

What happens when you test the "other" RCD!

 

[Midwest]

My meter does not give me the option of 3 lead test or 2 lead lest although it will carry out the test with two leads.
P-le on low or hi
And p-n on hi only.

I thought you said you had a Megger 1730?

 

[jord35davies]

Let me rephrase the question.

What happens when you test the "other" RCD!

Well if you read what I wrote it obviously stays on.

 

[jord35davies]

Yes

I thought you said you had a Megger 1730?

I have. It does not give me options of a 3 lead test or two lead test.

 

[jord35davies]

Most likely answer I think is a N-E fault somewhere in the installation.
Unless it's got a different type of RCD installed, either an A or B type instead of AC?

Yes that's the conclusion I came to. Thing is I've completely disconnected all circuits and tested them one by one, started with radials and it trips the rcd no matter which circuit I test.

 

[buzzlightyear]

now jord 35 witch tester have got.

 

[buzzlightyear]

is it a split load !
and when you tested did you do ring c/test .

 

[Octopus]

Well if you read what I wrote it obviously stays on.

I think you misunderstood my question.

The cu in question has 2 x rcd's, did you actually test the other one, and if so does it test properly,?

 

[buzzlightyear]

me and max are trying to get my head round this, the possibility he has over sensitive rcd ,he needs to put the tails from where rcd trips to the other side ,and see if that trips. swap rcd's if possible.

 

[Midwest]

Yes

I have. It does not give me options of a 3 lead test or two lead test.

I'm confused, which test option do you have? As I said before, my Megger 1730, gives the options of;
3 lead low, 2 lead low & 2 lead high Zs/Ze tests. I can't understand how yours does not? I'm really trying to help.

 

[jord35davies]

I think you misunderstood my question.

The cu in question has 2 x rcd's, did you actually test the other one, and if so does it test properly,?

I understood what u wrote, the rcds are fine under rcd test. They trip and comply with bs7671. Zs is the issue I'm having.

 

[jord35davies]

Yes

I'm confused, which test option do you have? As I said before, my Megger 1730, gives the options of;
3 lead low, 2 lead low & 2 lead high Zs/Ze tests. I can't understand how yours does not? I'm really trying to help.

there are two types of 1730. The earlier version does not give you the options. Yours is the new version 1730

 

[Midwest]

Yes

there are two types of 1730. The earlier version does not give you the options. Yours is the new version 1730

I see, I didn't realise that. Yours must have a really old firmware version, I purchased mine in 2012. Have you considered getting a firmware update? Megger offer that option with their calibration service £69 + vat.

 

[jord35davies]

I see, I didn't realise that. Yours must have a really old firmware version, I purchased mine in 2012. Have you considered getting a firmware update? Megger offer that option with their calibration service £69 + vat.

Think I'll have to. Thanks for your patience and feedback

 

[Midwest]

Your post has nudged my elderly memory. I seem to remember before I bought mine, of issues with the early 1730 firmware causing problems with certain RCD's, amongst other things. I've googled back a few pages, and there's quite a few references to that around 2012. Might be your issue? What is the make of RCD's?

 

[telectrix]

56 POSTS AND NOBODY'S SUGGESTED THE USE OF A HAMMER. I'M IMPRESSED.

 

[Octopus]

You should call the manufacturers technical help line!

 

[jord35davies]

Your post has nudged my elderly memory. I seem to remember before I bought mine, of issues with the early 1730 firmware causing problems with certain RCD's, amongst other things. I've googled back a few pages, and there's quite a few references to that around 2012. Might be your issue? What is the make of RCD's?

contactum

 

[Midwest]

Lot of shouting going on. You should all calm down, otherwise you'll have a coronary.

 

[Midwest]

contactum

It was Wylex. What version firmware have you got?

 

[buzzlightyear]

I had the same problem on the 1502/2 soft ware issue they said they had fix it
would not do zs test sent it sent it back sent a new megger

 

[tony mc]

I would want to get this job sorted so would just do it the old way on a high loop test bypassing the RCD!

Then I would sort my MFT issue out IMO !

 

[Davisonp]

When I had a problem with my 1730 tripping various RCD’s with a two lead low test, Megger suggested that different RCD windings react differently to testing, and to swap the live and earth leads for the test (send current the other way through the RCD), and it worked. Would it be possible to swap live and earth on one of your Zs tests sending the current the other way through the RCD?

 

[Davisonp]

.

 

[jord35davies]

When I had a problem with my 1730 tripping various RCD’s with a two lead low test, Megger suggested that different RCD windings react differently to testing, and to swap the live and earth leads for the test (send current the other way through the RCD), and it worked. Would it be possible to swap live and earth on one of your Zs tests sending the current the other way through the RCD?

Yes I could try that. TBH I've just used the alternative method of test sent by tel on one of the first posts and that has worked. It's given me my readings.
Thanks tho if it happens again I'll try that definately.

 

[jord35davies]

Been

I had the same problem on the 1502/2 soft ware issue they said they had fix it
would not do zs test sent it sent it back sent a new megger

in contact with megger and they're looking in to it. Thanks for all your posts seems they've had a lot of issues like this.

 

[Midwest]

If it's anything more than a firmware update, Meggers default repair charge is £220+carriage+vat. Just thought I'd mention that That does include calibration & firmware update.

 

[buzzlightyear]

jori 35 how is the land of my fathers, I would ring megger tell them the problem, and see what say and tell them its no point having
a tester if it can not do the proper functions like I did .

 

[Davisonp]

Yes I could try that. TBH I've just used the alternative method of test sent by tel on one of the first posts and that has worked. It's given me my readings.
Thanks tho if it happens again I'll try that definately.

I realised this morning that this will only work with the 2 lead testing.

 

[thomasgratton86]

hi guys,
Hoping for a little advice.
Been working on a property this week and have been having trouble getting zs readings as it trips the rcd on a 17th edition cu.
Property is pme. I've tried testing idividual circuits one by one and completely disconnecting all the others but it still trips. It doesn't seem to matter what circuit is tested it trips on every one.
I've checked absolutely everything and all tests leading up are fine. Zs tests however trip rcd.
I've done a ramp test on rcd to check that and it's fine.
I've got a feeling it's a Dno issue but they have now confirmed there are no faults on the line. Anyone had similar issues.
Thanks in advance

Hi for anyone still interested in this post.
I had a similar problem after replacing a bathroom fan and wanted to Zs but it kept tripping the RCD. I new my tester was on the correct setting and working fine.
Went to the circuit origin where the rcd was located. It was a split board. Tested the load side of the RCD with a Zs test and it tripped.
Turned off all the circuits and tested again at same point and it didn't trip. Turned on the circuit I want to test and test again and it didn't trip. When back to where I wanted to test from at the fan and it didn't trip.
Something on one of the socket ciruits was back feeding some how.

 

[Midwest]

You might have an IR fault on another circuit connected to that RCD.

 

[RichardM]

Disconnect all relevant circuits and test the RCD in the c/u. I have had a couple of instances where brand new RCDs have been faulty. (speaks volumes of todays q.c. procedures).
I read somewhere in the dark distant past that electrical / electronic items fail in the first couple of weeks or last a lifetime.

 

[brianmoooore]

I read somewhere in the dark distant past that electrical / electronic items fail in the first couple of weeks or last a lifetime.

Commonly known as the 'bathtub curve'.