what tests are you doing on consumer unit change.

[daz1963]

Hi all. when changing a consumer unit,what tests are you doing for eic?continuity of ring and bonds,insulation resistance,polarity,zs and rcd tests. or are you doing R1+R2 as well? i normally do the R1+R2 tests as well but takes extra time and is it really nessesary? on the ring mains i can understand the end to end, i,ve seen a few forums where some peeps are testing Zs but not R1+R2. i can,t find anything that says otherwise so not really sure whats right and whats wrong. any advice would be very welcome.
Regards Daz.

 

[Sparky Ninja]

Measuring R1&R2 or R2 is an absolute necessity on a consumer unit change.

Measuring Zs and obtaining R1&R2 from the measured value is cowboys work.


Make sure you fully understand the purpose of carrying out these individual tests then you should realise why they are essential.

 

[spark 68]

Hi,

I couldn't say what is right or wrong, but I usually test and record the lot, as there is rarely, if ever, prior paperwork.

I don't do a 'formal' EICR before hand, but still do a quick pre-test, how much depends on the condition of the installation, but I don't record this other than maybe the Ze and PFC which would go on the EIC, unless I need to change something that would affect this, ie. Earthing conductor or new rod, Main bonding or tails.

 

[Amp David]

I always find the titles of the columns on a schedule of results is a give away as regard what test are required. hone:

 

[Octopus]

Hi all. when changing a consumer unit,what tests are you doing for eic?continuity of ring and bonds,insulation resistance,polarity,zs and rcd tests. or are you doing R1+R2 as well? i normally do the R1+R2 tests as well but takes extra time and is it really nessesary?

Absolutely scarey.

If it takes extra time are you allowing sufficient time to do the job correctly? Cutting corners isn't the way forward.

 

[Mark_Burgess]

READ THIS THREAD http://www.electriciansforums.net/e...ctrical-regulations/12971-cu-changes-you.html

 

[daz1963]

who said anything about cutting corners. read my post again and you will see i test R1+R2. what i said was some people on this forum and other forums don,t. if you do a forum search on here you will see for yourself. but as i understand it R1+R2 is a dead test to verify a circuit is safe to energise and would meet disconnection times, Zs is is the live test what will also give you a value to ensure disconnection times are met. if you have a Zs reading and a Ze reading why do R1+R2? surely that should be enough. on a ring final yes to find any cross connections, or a full rewire.but on a previously installed radial? thats already been energised before it was switched off before commencing a cu change. correct me if i'm missing something here.
regards daz.

 

[pencilpusher]

Daz, I think he is referring to this comment "i normally do the R1+R2 tests as well but takes extra time" It comes across as a time issue TBH. Do all the tests. You are changing the nature of all the circuits by changing the CU. I treat that as a new install when testing. Safety first 'cos it has my (your) name on the EIC!

 

[daz1963]

Sorry. it does sound a bit that way. i never seem to be able to type what i want to say.
regards daz.

 

[roukel01]

Well, RCD's are installed nowadays so no need to do insulation resistance test, cos yer RCD won't set if there's a problem. Then a couple of Zs tests here and there to make sure you've got an earth.

The rest of the testing is carried out at home. :behead:

 

[brman]

Sorry. it does sound a bit that way. i never seem to be able to type what i want to say.regards daz.

I got what you meant!

sounded like a reasonable question to me - what do you get from an R1+R2 on a radial circuit that you don't get from a Zs?
If the answer is that you need the dead test 1st to check it is safe before energising then you can just do it before you isolate the installation before the CU change.

Personally I don't do a Zs measurement on radial circuits if I can help it. I use Ze+(R1+R2). Particularly on lighting circuits I don't like removing roses etc to get to the earth when the cct is live.

 

[plugsandsparks]

I like ZS tests cos after all the unscrewing and screwing of terminals i can test it last when its all done, gives me a warm comfy feeling i have left it all good.

 

[SirKit Breaker]

I like the new model EICR forms, and the generic test result schedule, takes away all the guess work as to what tests you should do, and it even has a tick box for operating the RCD test button.

Cheers...........Howard

 

[Des 56]

This is the ESC advise
10.2. In addition, as a minimum, the following testsshould be carried out to the existing circuits
connected to the replacement consumer unit.
• A continuity test of the protective conductor of
each circuit, to the point or accessory electrically
furthest from the consumer unit and to each
accessible exposed-conductive-part.
• A continuity test of all ring final circuit
conductors.
• A measurement of the combined insulation
resistance of all the circuits. The measurement
need only be made between the line and neutral
conductors connected together and the
protective conductor connected to the earthing
arrangement.
• A test of the polarity and a test to establish the
earth fault loop impedance (Zs
), at each
accessible socket-outlet and at least one point or
accessory in every other circuit, preferably the
point or accessory electrically furthest from the
consumer unit.



Note
R1+R2 values are not mentioned
Here is a link if you want to refer to their bumph
http://www.esc.org.uk/fileadmin/user_upload/documents/industry/best_practice/BPG6_09.pdf

 

[jase]

I got what you meant!

sounded like a reasonable question to me - what do you get from an R1+R2 on a radial circuit that you don't get from a Zs? Tell you what you dont get- parrallel paths
If the answer is that you need the dead test 1st to check it is safe before energising then you can just do it before you isolate the installation before the CU change.

Personally I don't do a Zs measurement on radial circuits if I can help it. I use Ze+(R1+R2). Particularly on lighting circuits I don't like removing roses etc to get to the earth when the cct is live.[/QUOzTE]

On initial verification there is no need to measure Zs, as this would have been measured by Ze + R1+R2, but on a periodical it is exceptable to measure Zs as the circuit is already energised, and write lim or NV in the R1+R2 box on the cert, on a fuse board change there is no reason not to measure Ze and R1+R2 as the installation will be de-energised anyway