Hi guys just a post wondering how people conduct their r2 tests. In the OSG it says to do it with a long lead attached to the met and test cpc at various points, what happens if you don't have a longlead? Is there an alternative?
R2 tests
- Thread starter Jacobssi
- Start date
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If you need to use that method, you can make up a wander/long lead out of singles cable, and null or deduct the resistance from the reading.
Or use a 240 or 110v extension lead.
Most people would do the R1+R2 instead (using the live as a 'wander lead'), as the live is present at all points.
R2 is generally only used for bonding.
Most people would do the R1+R2 instead (using the live as a 'wander lead'), as the live is present at all points.
R2 is generally only used for bonding.
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R2 testing can be used quite a lot when carrying out PIR's, especially on commercial or industrial premesis where parallel earth paths are in existance meaning an R1+R2 test is useless unless you can remove all parallel paths.
Either R1+R2 (test method 1) or R2 (test method 2), one or the other.
When using test method 1, polarity is confirmed as a matter of course whereas if you opt for R2 testing then you need to carry out a separate polarity test.
I assume you mean R2 and not r2?
r2 is the cpc end-to-end resistance of a ring final circuit.
How does that remove parallel paths? It can't.
A run of SWA from a DB to a socket. The DB and the socket are fixed to the steel structure of the building. How is the R2 going to do what the R1+R2 can't? To get the true R1+R2, you would disconnect the earth at the socket and test between the live and the earth in the cable only. If there where more than one socket in the circuit, you would need to disconnect them all, but in practice you would not.
Doing an R2 would make to difference.
Maybe not but an R1+R2 test would be just as meaningless.
R2 testing is faster and involves less disruption to the installation.
R2 testing is faster and involves less disruption to the installation.
I use either, it depends on the situation.
There's no right or wrong option.
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If this test is only carried out once in the sequence list in BS 7671 it does not confirm polarity. In fact no test can actually confirm polarity - because testing cannot reveal all faults.
GN3 says
"For radial circuits the (R1 + R2) measurements, made as in test method 1 (Section 2.7.5), should be made at each point."
Note that GN3 does not suggest that an (R1 + R2) test conducted to satisfy 612.2.2 can be used. The reason is that it might give a false positive due to a neutral to earth fault. This fault would not be revealed unit the tests in 613.3 are carried out. GN 3 is actually suggesting another additional test.
The sequence of testing is there for a reason.
Thats my point.
It is far easier to do an R1+R2. No cables to trail around, which can be impossible in some larger installs. I can't say I have seen anyone doing an R2 test other than for main bonding, and TBH, people even ommit that. (which is ok to do if you can confirm it visually).
Doing an R1+R2 also confirms polarity which allows you to miss a step in the testing.
Which is my point.
Dismantling was the word I was looking for at the time but it wouldn't come to me!
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