IET logo
 
IET
Decrease font size
Increase font size
Topic Title: R2 Testing Method
Topic Summary:
Created On: 30 July 2012 10:26 PM
Status: Post and Reply
Linear : Threading : Single : Branch
1 2 Next Last unread
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 30 July 2012 10:26 PM
User is offline View Users Profile Print this message



misterben

Posts: 415
Joined: 11 June 2007

Hi,

I have been informed that it is not acceptable to test using the R2 method rather than R1+R2. This is news to me, does anyone have opinions on this?

Misterben
 30 July 2012 10:38 PM
User is offline View Users Profile Print this message



daveparry1

Posts: 6094
Joined: 04 July 2007

Well, EIC's ask for either R1 +R2 or R2 and state that at least one of the columns must be completed so as far as i'm concerned an R2 reading is perfectly acceptable. I use R1 + R2 by choice but sometimes it's not practicable in which case it gets an R2 measurement?
As a matter of interest who said it's not acceptable?

Dave.
 30 July 2012 10:44 PM
User is offline View Users Profile Print this message



misterben

Posts: 415
Joined: 11 June 2007

Hi Dave,

A QS on a site I worked on, I always use R1+R2 where practical. The R2 method where I have had light fittings at a substantial height, I have used a pole/ wander lead. I dont see a problem with it?
Sometimes on particular decorative fittings it can be a pain using R1+R2, but have also used BC and ES adaptors.
I suppose a wander lead could be quicker

Misterben
 30 July 2012 11:22 PM
User is offline View Users Profile Print this message


Avatar for sparkiemike.
sparkiemike

Posts: 1529
Joined: 24 January 2008

Testing for what?

If you are only testing for "continuity of protective conductors" then either method will surfice.

However if you are going to use the results to test for polarity or use it determine Zs (by adding R1+R2 to Ze) then you will need the R1+R2 measurement.
 31 July 2012 06:53 AM
User is offline View Users Profile Print this message



MrP

Posts: 831
Joined: 24 March 2006

Ben
 31 July 2012 06:53 AM
User is offline View Users Profile Print this message



MrP

Posts: 831
Joined: 24 March 2006

Ben
 31 July 2012 06:57 AM
User is offline View Users Profile Print this message



MrP

Posts: 831
Joined: 24 March 2006

Ben
From your op I believe that it's an inspection of an existing installation that you are referring to therefore its what's agreed with the client prier to commencement of the inspection and testing if any
on an existing installation you dont have to do 1+2or 2+3 you do whats agreed

Sorry as above button got stuck

MrP
 31 July 2012 03:23 PM
User is offline View Users Profile Print this message


Avatar for jsa986.
jsa986

Posts: 472
Joined: 08 February 2011

Who was it that says R2 are not acceptable?

I have an opinion..a part p assessor misinformed again?

-------------------------
www.icertifi.co.uk
Electrical & Gas Certificates on iPhone & iPad
 01 August 2012 10:24 AM
User is offline View Users Profile Print this message



MrP

Posts: 831
Joined: 24 March 2006

Not got they latest green dot GN3 but is there still reference to inspecting and testing of an existing installation that excludes out of reach from a standing platform, in other words you don't need a wire on a pole or off a pair of steps if you are carrying out an inspection and test of an existing as per to GN3

I like the idea of a gold clad inspector swooping down to carry out the inspection

MrP
 01 August 2012 04:47 PM
User is offline View Users Profile Print this message



John Peckham

Posts: 7371
Joined: 23 April 2005

You might want to splash out on a new GN3 as there is a nice new health warning in there about R2 and R1 + R2 testing from those wise old buzzards from the IET.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 02 August 2012 06:48 AM
User is offline View Users Profile Print this message



MrP

Posts: 831
Joined: 24 March 2006

John
Not got the green dot and have no access to it
What is the R2 D2 health warning pray tell
Is the out of reach from a standing platform still in

MrP
"Splash out on a new book" do you think I'm made of money
 02 August 2012 10:34 AM
User is offline View Users Profile Print this message



jcm256

Posts: 1840
Joined: 01 April 2006

With statutory inspections, (for example Quarries) R2, measurements (with a wander lead) are determined six monthly, in-between the three-year cycle Re-validation of the line resistance. Although the wander lead method not be stated on a document under law, it is left open to common sense, would the inspector be popular or practices his trade every six-months by pulling covers of hundreds of motors, some of which are unreachable, blockage, upside down and seized lid screws. BS7671 is none statutory; why not use common sense with R2 inspections.

http://www.hse.gov.uk/quarries/electricity.htm
 02 August 2012 10:43 AM
User is offline View Users Profile Print this message


Avatar for jsa986.
jsa986

Posts: 472
Joined: 08 February 2011

Originally posted by: jcm256

why not use common sense with R2 inspections.



http://www.hse.gov.uk/quarries/electricity.htm


and with all aspects of BS 7671

-------------------------
www.icertifi.co.uk
Electrical & Gas Certificates on iPhone & iPad
 02 August 2012 12:51 PM
User is offline View Users Profile Print this message


Avatar for Parsley.
Parsley

Posts: 960
Joined: 04 November 2004

Originally posted by: MrP

John

Not got the green dot and have no access to it

What is the R2 D2 health warning pray tell

Is the out of reach from a standing platform still in

MrP

"Splash out on a new book" do you think I'm made of money


Mr P, There's a new note warning about the effects of parallel paths caused by exposed and extraneous conductive parts, metal stud walls etc that my bring the R2 value down towards zero. and the impracticalities of removing the parallel paths whilst carrying out testing.

I assume the original post refers to new installations and not EICR's where it's acceptable to verify earth continuity by earth fault loop impedance test. What suprises me is that I have seen R1+R2 readings entered on PIR/EICR sheets that have been calculated from Zs-Db readings. whilst I accept if its stated in the limitations that the R1+R2 values have been calculated; I don't see the point in entering a value that hasn't actually been measured.
There's also a note in the periodic testing section stating generally, accessibility may be considered to be within 3 m from the floor or from where a person can stand. Which I guess is what you were referring to.

Regards
 02 August 2012 01:55 PM
User is offline View Users Profile Print this message



misterben

Posts: 415
Joined: 11 June 2007

I was referring to an EICR , obviously any new works would be r1+r2.
I guess doing the R2 method does not take into account high line resistances, therefore apart from testing metal light fittings , motors and impracticable accessories i.e at height, is it acceptable?
I have tested several light fittings in a church via a wander lead on a pole, but am now wondering whether it is an effective method

Misterben
 02 August 2012 02:54 PM
User is offline View Users Profile Print this message



daveparry1

Posts: 6094
Joined: 04 July 2007

I don't really see much of a problem, it's true that you might not just be measuring the circuit's cpc but parallel paths too, but they are in place when the circuit is working so what difference does it make? If we're being really "picky" I suppose there may not be a continuous cpc and the R2 reading is being seen through some other path, eg water pipe etc. but rather unlikely i would think,

Dave.
 02 August 2012 04:07 PM
User is offline View Users Profile Print this message



MrP

Posts: 831
Joined: 24 March 2006

Parsley thank you very much for the information

Ben
What was agreed regarding the scope of your inspection before commencement?
And as another is questioning your inspection process I suspect that nothing was agreed other than the premises is to be inspected so you could be there some time and could be lead you a marry dance
The limitations box is by far the most important part of the document and lays out how the inspection is to proceed

Just for info and I'm sure you already know
Had you stated the inspection was too and as per GN3 accessible from where a man can stand, the light fittings would have outside the inspection scope

MrP
 03 August 2012 12:12 AM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 11268
Joined: 13 August 2003

if you are going to use the results to test for polarity .... then you will need the R1+R2 measurement.

Consider what an R1+R2 test will show if L and PE had been swapped over somewhere.

R1+R2 only verifies polarity (e.g. L is in the right place) if PE can be known to be good (it doesn't spot L and PE reversal).

R1+R2 only verifies PE continuity if L can be known to be good (it doesn't spot L and PE reversal).

Bit of a catch 22.

There was a suggestion that we should do a R1+Rn test (i.e. bridge PE and N at the DB and test between N and PE) in addition to R1+R2 (a bit like we do for rings) - that way a L-PE reversal would be detected (the R1+R2 test would show open circuit) and it would also detect any bad connections in N (something we seem to obstinately ignore and then ask why is it always N that burns out?)

Another alternative would be R1 (wander lead) in addition to R1+R2.

- Andy.
 03 August 2012 07:24 AM
User is offline View Users Profile Print this message



MrP

Posts: 831
Joined: 24 March 2006

Andy
That's why testing is part of a process (CRIPPER)
You cant just perform R1+R2 as a stand alone test. R1+R2 should be a by-product of conducting continuity and polarity at every point of utilisation, utilising a low res ohm metre and the best instrument your eyes

Bens problem is not the back sheet R2-D2 of the documentation but the front sheet where he did not lay down the scope of the inspection and test and unfortunately is endemic in the industry where proper electricians think that you have to pull the job apart and fill the back page with lots of meaningless numbers, in reality you don't have to test anything, you agree the scope of the inspection and that lays out the procedure and what tests if any are to be applied

It would be interesting to know what Ben agreed with the client and what is the scope of his work hopefully not just inspect and test the property

MrP Ram a dam a ding dong and not a lot happening in the 40's at 7.30am going to be a hot one
 06 August 2012 04:08 PM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 11268
Joined: 13 August 2003

That's why testing is part of a process (CRIPPER)
You cant just perform R1+R2 as a stand alone test. R1+R2 should be a by-product of conducting continuity and polarity at every point of utilisation, utilising a low res ohm metre and the best instrument your eyes

Yes, but physically how do you carry out continuity & polarity tests? Some have suggested that the "R1+R2" test (i.e. "Test method 1" in GN 3 speak) does both. Connections can be made a several locations, not just at the DB and point of utilisation, so eyes (checking right coloured wires into right terminals) aren't necessarily a sufficient safeguard.
- Andy.
IET » Wiring and the regulations » R2 Testing Method

1 2 Next Last unread
Topic Tools Topic Tools
Statistics

See Also:



FuseTalk Standard Edition v3.2 - © 1999-2014 FuseTalk Inc. All rights reserved.