A silly questions on Countituy testing

[nazoom]

I am still in the training process. I have one question if anyone can help thatll be great.
My question is when carrying out continuity test on a radial circuit I know we have to link. When linking can we just link between the main Earthing terminal and circuit breaker? or does it have to be the exact cpc for that circuit and CB?

Many Thanks

 

[telectrix]

for measuring R1+R2, you would measure just the cable concerned. link the L and cpc of the cable at CU, then measure at points. furthest point is your recorded result.

 

[Plonker 3]

No you can put a link between the earth bar and MCB outgoing side. Sometimes it isn't possible to properly identify the correct cpc (eg when wired in singles)

 

[Octopus]

Best practice, and if you can identify the correct cpc would be to remove the CPC and R1 from the board, link and measure at the end. This way you shouldn't have any parallel paths.

 

[nazoom]

I know that I have to disconnect the main earthing and bonding conductor to avoid parallel paths. So is it accurate to just link between the CB for the circuit and the Main Earthing terminal , as MET has too many cpcs?

Thanks again.

 

[ferg]

If you can get your hands on a copy of guidance note 3 you will find it invaluable.
It's not overly expensive and is very clear.
The copy I have even has a pictures showing how to do the tests.
GN3, pre amendment advised Dillbs method but if I remember correctly for the 2391 tel and murdoch's method is the correct one and dillb's method was not advised.

go figure lol :rolleyes2:

 

[nazoom]

I looked it up in the GN3 but still unsure! please I need an answer.

Many Thanks

 

[ferg]

p32 GN3.
It advises the use of a temporary link between line of the cct and the cpc bar.
When I did the 2391 we were told not to use the temp link but to use the cpc and line conductor connected together.

As far as I'm aware you remove the main earth for a Ze test to eliminate parallel paths but this is not necessary for R1+R2