Continuity of cpc's R1+R2

[sparko]

Hi guys, when testing continuity of cpc's r1+r2 method, with main switch isolated, can you link from the live bus bar to the main earth bar in the C.U with a small croc clip and just turn mcb on for the circuit under test? If not at which exact point would you link the line and earth in the C.U?

 

[Guest123]

Hi guys, when testing continuity of cpc's r1+r2 method, with main switch isolated, can you link from the live bus bar to the main earth bar in the C.U with a small croc clip and just turn mcb on for the circuit under test?

Yes. This also confirms the MCB is sound.

See pic advertising the leads you describe and their use.....Ignore the fact that ALL MCB's and the RCD is switched on!!

 

[Jimmy Boy]

Just have the wire out the breaker and the CPC out the Earthing terminal and chocky them together, if it's a ring you will have to have them all out anyway as the first step of ring final circuit test is end to end resistances of L/N/E start as you mean to go on

 

[Amp David]

Out of the MCBand earth bar them use those jump leads which are pretty good

 

[telectrix]

i very often us an alternative method. breakout box in socket and link L/E or N/E, then test at CU. move box to each socket in turn and record highest reading. have to remember to remove link before energising though.

 

[BigBreakfast]

I prefer this method too using the link between bus bar and earth and as Lenny says this proves the mcb and saves a good bit of time regarding disconnecting ends etc.

 

[telectrix]

but should the internal resistance of the MCB be included in R1+R2?

 

[BigBreakfast]

but should the internal resistance of the MCB be included in R1+R2?

Wondered the very same thing when first adopting this method, but could find little if any difference in any circuit that I would test using both methods so far.

 

[andyb]

Ignore the fact that ALL MCB's and the RCD is switched on!!

I imagine that the main switch is off, I'm more interested in what is being tested as there seems to be no circuits in the mcbs.

 

[telectrix]

think Lenny was showing the pic for illustration purposes.

 

[Guest123]

but should the internal resistance of the MCB be included in R1+R2?

Well technically there shouldn't be any of any note and if there was this should highlight the problem. The only other reference to MCB soundness is Zs but as a lot of people prefer to calculate, we're only left with this.

All IMO.

 

[Deleted member 9648]

The only thing that bothers me with the link to busbar method is forgetting to remove it before switching on........shouldnt happen I know, but it's late on a friday and you are almost done....you know how it is....BIG BANG....I'd want a fused link.

 

[Guest123]

The only thing that bothers me with the link to busbar method is forgetting to remove it before switching on........shouldnt happen I know, but it's late on a friday and you are almost done....you know how it is....BIG BANG

Only too well!!!!!!!!!


To be fair it was in my mis spent youth when all that mattered was alchohol intake.

 

[Jimmy Boy]

Would any of the methods noted be acceptable methods for an NICEIC annual reassessment ?

ATB Steve

 

[Jimmy Boy]

A fused link could add substantial resistance to the measurement

 

[k.k]

Surely using the link is deemed safe enough a practice, as it seems common practice by many sparks, or would NICIEC frown on this method

 

[Des 56]

The main isolator is switched off,verified dead, and locked out,he has no reason to frown on that method

It is worthwhile when linking out the bus bar to the earth strip, to measure each mcb resistance,the values sometimes dont make good reading
Your circuits, like up lights and down lights etc, can be checked that they are labelled correctly, by switching on the mcbs individually whilst taking their readings
It shouldn't be necessary ,but many times we see incorrect labelling,it would be shown up by this method

 

[ezzzekiel]

The only thing that bothers me with the link to busbar method is forgetting to remove it before switching on........shouldnt happen I know, but it's late on a friday and you are almost done....you know how it is....BIG BANG....I'd want a fused link.

quite a favourite of mine, which is why i use a piece of wire just pushed lightly into top of mcb and screwed into earth bar so when i forget to remove it the bang blows it clear if i left it croc clipped then youre probably gonna lose the service fuse also or have a much greater bang

 

[Deleted member 9648]

Linking off the load side of the MCB doesnt bother me as you have some protection from the mcb...but as you say,straight on to the busbar....you are really going to regret if you forget to remove that link.

 

[k.k]

just out of interest how often does it happen .Not often i would have thought. Ezzzekiel method sounds like a good one , but doesn't it effect the readings,with resistance, or is it nominal?

 

[malcolmsanford]

Having the misfortune over the years of having a few bangs on testing and looking really silly, I tend to disconnect the LINE from the protection device and if there is an easily accessible way on the earth bar connect it direct into it. If there isn't then croc clips on the bar and onto the conductor.