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Discuss r2 readings too high? in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

S

#### sivoodoo

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Are these readings for r2 (not R2) too high?

kitchen ring: r1= 0.13 rn = 0.12 r2 = 0.33
cellar/living room ring : r1= 0.15 rn = 0.15 r2 = 0.40
Bedroom1 and 2: r1= 0.48 rn = 0.48 r2 = 1.17

what could be the problem if so?

Si.

A

#### AlanDavies

Hi sivoodoo

Are the cables in question new or old?

Could be that the cpc be 1.0 mm. This would fit as the figures in bold a 2.5 times greater than the other figures which would fit with a 2.5 / 1.0 cable.

S

#### sivoodoo

Im not sure on the cpc size, whats the best way to tell?

Also where can i find a table that will give me the factors for different size conductors?
i.e 1.667 for 1.5mm etc.
Thanks

A

#### AlanDavies

I don't know where the information can be found, but I think it can be calculated:

2.5 / 1.5 = 1.6666666667 (rounded up = 1.667)

2.5 / 1.0 = 2.5

Are the cables red and black ?

S

#### sivoodoo

yes, red and black.

A

#### AlanDavies

The figures suggest to me that the cpc is 1.0mm. I believe that in the past there were 2.5/1.0 cables.

Is it that the figures just don't make sense or are they outside the regulations?

S

#### sivoodoo

I was presuming they were 1.5mm cpc, but the calculations point to 1mm cpc, Im happy with this, i need a tool to measure the diameter of conductors as i find it hard to tell on the smaller cables.

Thanks

#### old dog

##### -
Arms
2.5 = 7.41, 1.0 = 18.10 take your cicuit at 18 meters
7.41 x 18 /1000 = 0.13
18.10 x 18/1000 = 0.32

F

#### flukeyspark

Hi old dog,
Is this calulation in the osg? If not where?

#### old dog

##### -
Arms
Hi old dog,
Is this calulation in the osg? If not where?
hi not sure where the calculation is i am in the middle of my 2391
so i do know the calc is correct i will have a look and get back to you

E

#### ezzzekiel

same as vd calc without ib

mva x length / 1000 =

#### old dog

##### -
Arms
same as vd calc without ib

mva x length / 1000 =
yep thats the one

K

#### kung

use a caliper and measure size !

E

#### electro

Hi

Fit an RCD, you will soon forget about those R2 figures.....

Regards

#### mrloy99

##### -
Im not sure on the cpc size, whats the best way to tell?

Also where can i find a table that will give me the factors for different size conductors?
i.e 1.667 for 1.5mm etc.
Thanks
hi S,
maybe this will help-(you could use crimp lugs to determine size.)
I think this is from GN1
values resistance of copper at 20 oC mohm/m (move decimal point 3spaces to get ohm/metre)
1mm----18.10
1.5mm--12.10
2.5mm---7.41
4mm-----4.61
6mm-----3.08
10mm----1.83
16mm----1.15

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