Rcd tripping when doing zs test

[Delboy247]

Rcd tripping while doing zs test any suggestions would be great.

 

[IQ Electrical]

What tester are you using?

Are you using it on 'no trip' setting?

Are you using all 3 leads if required?

If all else fails, can you measure R1+R2 and calculate Zs?

 

[Sintra]

As IQ says you need to give us more info on what test meter you are using and how you are performing the test.

 

[Hawk81]

Have you done a ramp test?

 

[malcolmsanford]

You can also test the ZS at the board.

Isolate your circuit and at the circuits furthest point cross connect the LINE-CPC, as you would if doing a R1=R2 test at your CU.

Set the MFT to the EFLI test and place the black probe on the load side of your isolated protective device ie MCB and your red probe on the supply side of your RCD and test as normal.

 

[Delboy247]

The tester is a fluke 1652 using a 3 lead test for zs it seems strange as it's never happened before if anyone come across it before cheers.

 

[sparkinlee]

You can also test the ZS at the board.

Isolate your circuit and at the circuits furthest point cross connect the LINE-CPC, as you would if doing a R1=R2 test at your CU.

Set the MFT to the EFLI test and place the black probe on the load side of your isolated protective device ie MCB and your red probe on the supply side of your RCD and test as normal.

I like that... a two wire Zs test for RCD protected circuits (if I've followed correctly it will work for a radial simply by connecting L-cpc at the remote end of the circuit).

Is this method described in the books anywhere - I don't remember seeing it before

 

[tony mc]

I think Chris kitcher has it in his Practical guide to Inpection & testing.

Sometimes when you get high ZS readings on the no trip you can use this method to bypass the RCD and get your expected reading of your dead tests plus ZE.

Its only a 2 wire test if your meter can do that on my second meter I have to join the earth and neutral leads or it will not function.

Don't forget to remove your link from the CPC to Line at the end of the test !!!

 

[gap30]

whats the rating of the rcd? could it be a rcd? have you tried swapping the breaker/rcd to see if its a problem on the circuit, or as posted earlier work it out by calculation

 

[telectrix]

if you are performing the test as you have done before, and had no problems, i suspect that there is leakage on the installation and/or an RCD that is tripping at too low a current. so that your test current is taking it over the threshold, and so it trips. a ramp test on the RCD will verify this.

 

[bleach]

I have a Kewtech KT62 MFT which doesn't have the 'no trip' setting. Does this mean I will have no choice but to always calculate zs? Am I right in thinking that bypassing or short cicuiting RCDs is not allowed?

So does this mean I will be able to measure zs with a no trip tester?: Isolate your circuit and at the circuits furthest point cross connect the LINE-CPC, as you would if doing a R1=R2 test at your CU.

Set the MFT to the EFLI test and place the black probe on the load side of your isolated protective device ie MCB and your red probe on the supply side of your RCD and test as
normal.


Thanks

 

[plugsandsparks]

I have the KT65 and it defaults to anti trip for every reading, most of the time i am not needing anti trip and it is so annoying to have to keep pressing the function button to get rid of the anti trip, which BTW takes about 5 times longer to compute. I spoke with kewtech to see if there was a way i could alter the default but apparently not.

 

[needasparks]

Would have thought he had sussed it by now. check the date.

 

[plugsandsparks]

Was just having a moan about the KT65 to Bleach

 

[bleach]

Hi plugsandsparks

Thanks. I am fairly new and still learning. I did think maybe I would be better off with the KT65. I am still confused though about measuring a zs with my KT62 which doesnt have the no trip function. Does it mean it will trip an RCD every time I test zs and prevent a genuine reading?