How to do Ze test

[seanpress]

How to do Ze ie two lead high test using the Robin kts 1620 instruction, not sure what settings to use ie 20 ohms 200 ohms or 2000 ohms and for the psc ie 200a 2000A or 20KA any help is much appreciated

 

[seanpress]

How to do Ze ie two lead high test using the Robin kts 1620 instruction, not sure what settings to use ie 20 ohms 200 ohms or 2000 ohms and for the psc ie 200a 2000A or 20KA any help is much appreciated

Does no one want to help or give an answer

 

[pc1966]

Maybe no one has used that model? Presumably you don't have the instruction book now?

Recent MFT auto-range so you just connect up, double-check no one is doing anything to the electrics elsewhere, and press the test button.

As a rule any TN-S or TN-C-S is going to be less than 20 ohms if in good condition so you could assume that, where as TT you might start on 2k and then go down to 200 ohms if (as it should be) the rod is below 200 ohms.

I don't know if that model has any safety features to stop > 50V on the earth under test, so starting high R and dropping down ought to keep the volts to a level that is safe.

 

[westward10]

Been using Robin for years, not that model but they normally need three leads.

 

[seanpress]

Maybe no one has used that model? Presumably you don't have the instruction book now?

Recent MFT auto-range so you just connect up, double-check no one is doing anything to the electrics elsewhere, and press the test button.

As a rule any TN-S or TN-C-S is going to be less than 20 ohms if in good condition so you could assume that, where as TT you might start on 2k and then go down to 200 ohms if (as it should be) the rod is below 200 ohms.

I don't know if that model has any safety features to stop > 50V on the earth under test, so starting high R and dropping down ought to keep the volts to a level that is safe.

Thank you
The Robin kts 1620 has two sets of Leeds one is for testing at the socket and one is for testing at the consumer unit this set is a three lead one red probe one black with crocadial clip and one green with crocadial clip book says nothing about external loop impedance testing just zs

 

[pc1966]

book says nothing about external loop impedance testing just zs

Measuring Ze is exactly the same as Zs, except you need to have the supply to all circuits off and have isolated the incoming earth to test to it.

Normally Zs is slightly lower than Ze due to parallel paths to Earth from bonding to water, gas, etc. It can be significantly lower if you are in a block of flats, etc, so all of the extraneous pipes are also well-bonded to the supply earth and are not just relying on metal in ground.

 

[seanpress]

Been using Robin for years, not that model but they normally need three leads.

Thank you for your help
So do we need to do Ze test I keep hearing about doing the external earth loop impedance as two lead high ie remove the main 16mm earth from the cu connect one leed with crocadial clip to that and with the red lead probe on to the incoming line

 

[dodger421]

Apparently it’s a very similar tester to the Kewtech KT62, manual for which is here;

https://www.electriciansforums.net/attachments/kt62_manual-pdf.13959/

From a post on a similar subject here

https://www.electriciansforums.net/threads/robin-kts-1620-manual.1514/

 

[westward10]

That is correct but ensure the dist board is switched off with the earthing conductor disconnected.

 

[pc1966]

You really should check Ze as Zs can magically become higher in the future when someone changes a service pipe to plastic and those parallel paths are largely gone! Much more so on TT when the rod might be rubbish and so far the installation has really been relying on the water pipe, etc.

Some MFT will do two-lead tests, other demand all 3 are connected. If accessing the supply N when isolated for a 3-lead test is difficult then put N & E together to the supply CPC and then the probe to L for the test.

 

[GBDamo]

Does no one want to help or give an answer

Personally, I haven't a clue, sorry.

 

[seanpress]

You really should check Ze as Zs can magically become higher in the future when someone changes a service pipe to plastic and those parallel paths are largely gone! Much more so on TT when the rod might be rubbish and so far the installation has really been relying on the water pipe, etc.

Some MFT will do two-lead tests, other demand all 3 are connected. If accessing the supply N when isolated for a 3-lead test is difficult then put N & E together to the supply CPC and then the probe to L for the test.

Thank you that's a big help

 

[seanpress]

When doing a psc test using the Robin kts 1620 MFT what do you set the PSC dial to 200A 2000A or 20KA? or should I start with 20KA and then work down the scale? TNC-S SYSTEM

 

[pc1966]

When doing a psc test using the Robin kts 1620 MFT what do you set the PSC dial to 200A 2000A or 20KA? or should I start with 20KA and then work down the scale? TNC-S SYSTEM

Start on the lowest 200A range, and if it is over that go up.

That way if it lacks any safety features to limit the earth rise during test you keep it to a minimum.

 

[Vortigern]

So when you are doing a Ze or Zs the expected ranges are <0.8 ohms or <0.35 ohms unless testing a TT system. So it is a low range test. You are not actually testing the PFC, you calculate that from the measurement found on doing the above tests.