Testing for Bridges and r1, r2, R1+R2

[Casterbridge]

1. Ring: I have cross connected phase and neutral at the CU and measured resistance at each socket to confirm no bridges - readings should not vary more than 0.05 ohms as I understand. Should I be concerned that using the plug attachment for the megger on the front of the socket the readings are high AND they vary (e.g. 0.5ohms - 1.5 ohms) when they are 0.3 when the face is dropped? They seem the vary with swtiching the socket on and off, and is the same for all of the sockets ... BUT is this what is often seen????

2. Ring: To Calculate R1+R2 is it acceptable to measure r1 and r2 and then calculate or should you always cross connect phase and cpc and go to each socket to take the highest reading?

 

[PrenticeBoyofDerry]

1. Ring: I have cross connected phase and neutral at the CU and measured resistance at each socket to confirm no bridges - readings should not vary more than 0.05 ohms as I understand. Should I be concerned that using the plug attachment for the megger on the front of the socket the readings are high AND they vary (e.g. 0.5ohms - 1.5 ohms) when they are 0.3 when the face is dropped? They seem the vary with swtiching the socket on and off, and is the same for all of the sockets ... BUT is this what is often seen????

It is quite common, that sockets will raise the readings.

2. Ring: To Calculate R1+R2 is it acceptable to measure r1 and r2 and then calculate or should you always cross connect phase and cpc and go to each socket to take the highest reading?

I would say the latter.

 

[Sherbertlion]

Agree with the above. And also the socket lead adapters in my experience go high resistance quite often too.

If you don't do the fig 8 test for R1R2 then you won't pick up any NE reversals if the circuit isn't RCD protected (assuming that the R1RN test isn't carried out as a matter of course).