R1 + R2 does not equal (R1+R2) in example in On Site Guide.

[Flanders]

r is for ring
R is for resistance
R1 + R2 is the resistance of the earth and line of the circuit connected together

but if you do add r1 and r2 together and divide by 4 you should get R1 + R2 in theory

Due to parellel Earths though you may not get a text book reading

As stated R and r are completely diferent

 

[KAS1]

clear to me, but you couldn't of read GB£ page 100 note 13 Is that clear?

Yes but col. 13 IS R1+R2.

He was wondering why cols. 10 (r1) and 12 (r2) do not add up to col 13 because he mistakenly called them R1 and R2.

As I wrote, mine do as they ARE R1 and R2 not r1 and r2.

Col. 11 (rn or Rn) is incidental but the same.

Is that clear?

 

[Geoffsd]

clear to me, but you couldn't of read GB£ page 100 note 13 Is that clear?

I presume you mean "I can't have read GN3 page 100 note 13".

What does it say?

 

[KAS1]

Yes sorry, trying to do more than 1 thing at a time...................I'll let you have a read and see what you read into it lol

I presume you mean "I can't have read GN3 page 100 note 13".

What does it say?

 

[Geoffsd]

I have found it in the BGB.

You mean measuring from a spur would make R1+R2 more than (r1+r2)/4.

That would be true but I still think you have missed the point of the OP and my comments.

 

[Dubbo]

I have always been a bit confused about boxes 10,12 and 13 in the example of a completed 'Form 4 - schedule of test results'.

I understand why the value we get for R1+R2 (when measured at a socket) is a quarter of the end to end resistances, but why on the form is this not more clear?

Box 10 (R1) and Box 11 (R2) do not equal Box 13 (R1 + R2). Again I understand why, but it just seems wrong to have a box for R1 and a box for R2 but adding them together is not R1+R2.

Its annoying :cuss:

The form is correct as boxes 10,11 and 12 are asking for the end to end resistance for r1 , rn and r2 , these are all end to end resistances as in step 1 of the ring final circuit test to check that they are substantially the same , the true R1 + R2 of the circuit is established in step 3 by cross connecting R1 and R2 and measuring at each socket outlet this goes in box 13 . If you add up box 10 and 12 and divide by 4 this cross references your R1 and R2 .

 

[varilite]

It's really quite simple, if doing an EICR the installation has power so only need to do end to end to make sure it's a ring then do. ZS at each socket. If no power then you have to do R1+R2 and work out ZS by adding it to ZE.