# Calculating rings ### Help Support Talk Electrician Forum: #### Barx

##### Developer
Alright fellas,

We all know that the resistance of R2 is (should be) 1.67 times that of R1 (or Rn) on rings. We also know that adding R1 to R2 gives us (...Wait for it...) R1+ R2. Nowt new here yet.

But...

Do you know how to reverse it. i.e. Calculating R1 and R2 from R1 + R2?

If you do 'R1+R2' * 1.4981273408 you will get R1. Then obviously back to R1 * 1.67 for R2.

There you, has its uses.

#### binky

##### eco warrior......™
Alright fellas,We all know that the resistance of R2 is (should be) 1.67 times that of R1 (or Rn) on rings. We also know that adding R1 to R2 gives us (...Wait for it...) R1+ R2. Nowt new here yet.

But...

Do you know how to reverse it. i.e. Calculating R1 and R2 from R1 + R2?

If you do 'R1+R2' * 1.4981273408 you will get R1. Then obviously back to R1 * 1.67 for R2.

There you, has its uses.
How many decimal points:O

#### kme

##### Fridge Keyholder™
Alright fellas,We all know that the resistance of R2 is (should be) 1.67 times that of R1 (or Rn) on rings. We also know that adding R1 to R2 gives us (...Wait for it...) R1+ R2. Nowt new here yet.

But...

Do you know how to reverse it. i.e. Calculating R1 and R2 from R1 + R2?

If you do 'R1+R2' * 1.4981273408 you will get R1. Then obviously back to R1 * 1.67 for R2.

There you, has its uses.
EH???????????

Put more water with your next one mate!!!!!!! There obviously a bit strong for you.

Now then. Should you wish or need to do this (for whatever esoteric reason), here is the "easy" way.

Lets take an example:

R1=4.3 ohms

ergo R2=4.3 X 1.67 = 7.19

so R1+R2=11.49 ohms.

Clear so far.......................???????

Now. If you wanted to work it backwards; simply divide 11.49 by the magic number of *********2.67************

Result: 4.29 ohms. Close enough for anyone.

N.b. If you wanted to be lazy, and determine R2 instead; just use the OTHER magic number, 1.6. i.e. 11.49 / 1.6 =7.19.

Isn`t that so much easier??????????

n.b. Lets try your way, shall we?

R1=10 ohms. R2=10X1.67 =16.7 ohms

R1+R2=26.7 ohms

Your version: 26.7 X1.4981273408 = 40?????

My version : 26.7 / 2.67 = 10

#### Barx

##### Developer
Ahhhhh, explained it wrong. This is for ring finals were R1 + R2 = (R1 ring + R2 ring) / 4.

The long number reverses this calculation, giving you what your ring continuities should be from a R1+R2 figure.

Confused myself then for a while.

No wonder it took a long time for a reply.

An example:

R1 ring = 0.43 (domestic )

R2 ring = 0.43 x 1.67 = 0.7181

R1 + R2 = (0.43 x 1.67) / 4 = 0.287025 (I like to precise)

So......

R1 + R2 = 0.287025

0.287025 x 1.4981273408 = 0.43 (R1)

You get me drift now Sorry for confusion.

#### steptoe

##### of course Im wrong, ask my wife™
R1+r2 / 8 X 3 = R1

#### Barx

##### Developer
R1+r2 / 8 X 3 = R1
Are you sure??

Using above example:

R1+R2 = 0.28

...0.28 / 8 = 0.035

......0.035 x 3 = 0.105

No where near the 0.43 we started with.

Anyways looks like this is only useful for me. Thought I had come up with something kewl. But no.....Blushing

lol, ahhh well.