R1 + R2 expected readings

[Lt1990]

Has anyone got a table of expected R1 + R2 readings that give a guide to what readings we should be getting when testing

 

[timhoward]

Okay, if i had a radial circuit wired in 6mm/6mm swa and the measured R1/R2 was 0.16ohms. What table or resistance value would you personally use to calculate the length of that circuit as a reference point, and what length would you calculate?

Since you disagree with using the onsite tables and the procert one, im curious what you would use?

I think we have ended up slightly at cross purposes. I have no issue with anyone using OSG, BS7671, Pro Certs, or any other reliable reference of the resistance of copper in order to work out expected R1+R2 values.

My emphasis was intended to be on the "all the OP needs".
I'm a little bit concerned that anyone is having to undertake EICRs and asking some of the questions above, apparently without being provided with the latest regs book or OSG.
I don't mind using this forum to further my own understanding and in turn to try and help other people increase their understanding, but sometimes it feels like people are put in impossible situations by their employers and are expected to run before they can walk.

 

[loz2754]

Two things concern me about this thread:
1. The OP is conducting EICRs but not doing any live testing.
2. The OP is conducting EICRs without knowing basic things like how to calculate R1 and R2 values.
3. Sorry there is no third thing

 

[DPG]

Two things concern me about this thread:
1. The OP is conducting EICRs but not doing any live testing.
2. The OP is conducting EICRs without knowing basic things like how to calculate R1 and R2 values.
3. Sorry there is no third thing

The third thing for me is that the OP doesn't seem to see the problem of the first two points.

 

[buzzlightyear]

The op can grasp the concept on testing
R1+R2 and calculations on how to do it
My advice is to get a good book on testing.

 

[Lt1990]

I have a good understanding on electrics and testing and what I should be looking for and testing
The company I now work for only require us to do dead testing and then calculate the zs readings
All I was wondering is if they was a table about I could use as a guide for r1 r2 readings so I know my readings are correct or slightly high and I need to do abit of further investigation on circuits
Previously I’d do dead and live testing and I’d be able to check check the r1 r2 results by the zs readings

 

[Lt1990]

If I had my own way I’d be doing dead and live testing but when the company doesn’t want us doing it and to just calculate zs results then I’m going to do what I’ve been told to

Two things concern me about this thread:
1. The OP is conducting EICRs but not doing any live testing.
2. The OP is conducting EICRs without knowing basic things like how to calculate R1 and R2 values.
3. Sorry there is no third thing

 

[DPG]

Does nobody do any live testing?
Who signs the certs?

 

[timhoward]

All I was wondering is if they was a table about I could use as a guide for r1 r2 readings so I know my readings are correct or slightly high and I need to do abit of further investigation on circuits

For EICR purposes, the two things that come to mind are how close the calculated Zs is to the limit for the device, and a sense of how big the property you are in is and whether a reading seems plausible. The more you do the easier that gets.
e.g. if you're re in 2 up 2 down and you get 1.5 ohms for an immersion heater circuit then a bit of head scratching is due.

The other thing you can do is try RN+R2 or use a wander lead to obtain a 2nd frame of reference, and whether it's R1, R2 or both that have a loose connection.

I'm assuming that you are allowed to do Ze, Zs@DB and RCD tests, and your company only prohibits live Zs readings?

 

[ipf]

This is so basic for someone qualified. Whether dead or live testing, you should know the methods of carrying them out (and working them out) without thinking.

 

[westward10]

This is a 'modern' take on Zs testing that you don't do it live except for socket outlets where there is no risk of exposed live parts but as @timhoward asks do you carry out Ze and rcd tests.

 

[cireland]

Previously I’d do dead and live testing and I’d be able to check check the r1 r2 results by the zs readings

Surely a bad connection is going to make BOTH readings off.
How does live testing confirm anything is ok?

 

[Lt1990]

For EICR purposes, the two things that come to mind are how close the calculated Zs is to the limit for the device, and a sense of how big the property you are in is and whether a reading seems plausible. The more you do the easier that gets.
e.g. if you're re in 2 up 2 down and you get 1.5 ohms for an immersion heater circuit then a bit of head scratching is due.

The other thing you can do is try RN+R2 or use a wander lead to obtain a 2nd frame of reference, and whether it's R1, R2 or both that have a loose connection.

I'm assuming that you are allowed to do Ze, Zs@DB and RCD tests, and your company only prohibits live Zs readings?

Yea I generat know what I’m looking at what seems high and things but I just wanted something to work towards incase I was been slightly generous and over cautious chasing faults that didn’t really need further investigation.

And yea so we do ze zsdb And rcd tests
It’s literally just only zs readings that we can’t do

 

[Lt1990]

This is so basic for someone qualified. Whether dead or live testing, you should know the methods of carrying them out (and working them out) without thinking.

I do know the methods for carrying them and things,
I was just asking to know so I knew if I was over cautious or to generous when it came to the readings

 

[Lt1990]

This is a 'modern' take on Zs testing that you don't do it live except for socket outlets where there is no risk of exposed live parts but as @timhoward asks do you carry out Ze and rcd tests.

Yea we carry out ze and rcd tests
It’s just the zs we don’t carry out

 

[Vortigern]

You are either going to be carrying Zs on lights or sockets principally. Spurs come into it as well. I always do live tests at sockets, spurs and lights. I use the lightmate by Kewtech for Zs test. On courses it has been put to me this is a Lim, as you have to go up a ladder and H&S forbid this in many scenarios. I just get on with the job and test it all. When I put the Zs reading for each circuit I like to be sure I did actually read it with my MFT, I can't imagine any other way to operate. Maybe I am missing something, but I don't think so. Convince me! I mean how do you fill in the forms? Yes calculation, but I am not convinced that is kosher. For instance you can find that there are big variances between R1/R2 + Ze calculation and Zs measured with an MFT.