R1+ R2 Resistance

[stevebrands]

Hi, i have just done a resistance check of my phase loop and the earth loop in my socket ring main and totalled the figures. I am getting around 0.78 ohms. is this ok

[stevebrands]

Is there a value per M for 1.5 and 2.5 mm cable T&E

[sparky40]

Hello.
The resistance of your phase and earth will be different due to them being different sizes.
What were the readings for each conductors 'ring' ?
Let's not forget r1, and R1 are not the same eh !

[stevebrands]

the earth was about 0.5 ohms and the live was about 0.28 ohms i think. what do you mean about R1 and r1

[sparky40]

Read Nick the dentists post, this should help you.

[Optician]

Am I right in thinking this is not how you measure R1+R2, and you are in fact only measuring continuity of ring and therefore the CPC should be 1.67 x higher than the resistance of the phase and the neutral.

[Spark123]

r1 is the end to end resistance of the phase conductor
r2 is the end to end resistance of the CPC
rn is the end to end resistance of the neutral
When using flat twin and earth the end to end resistance of the CPC will be 1.667 times higher than that of the phase and neutrals which should be the same.
To ensure the polarity is correct you should cross the phase to neutral leg 1 and leg 2 conductors at the CU and test the phase to neutral resistance at each socket. You should have very close to (r1+rn)/4 at each socket except for spurs.
To measure R1+R2, put the phase and earth interconnections in at the consumer unit i.e. leg 1 phase to leg 2 cpc, leg 1 cpc to leg 2 phase and then go around and test the phase to earth resistance at each socket, the resistance at each socket on the ring should be very close to (r1+r2)/4. Any spurs will be have a higher resistance, the highest reading is taken as R1+R2.

[GaryMo]

stevebrands wrote:

Is there a value per M for 1.5 and 2.5 mm cable T&E

1.5/1.0 t&e - 0.0302 ohms per meter (30.20mohms/m)
2.5/1/5 t&e - 0.01951 ohms per meter (19.51mohms/m)