Ring main testing

[piz]

hello I am confused rewired a house this week but I dont do much testing on the ring main as a domestic installer normal kitchen fitting radial cooker extra lights etc I rememberr being told this takes a bit of getting used to
this is what has happened so far r1 = 0.48 rn=0.72 r2=0.90 I know that we divide 2.5 by 1.5=1.666*by r1 this should be calculated cpc reading
then on my sheet it says R1+R2 I have cross connected live and cpc on the ring and gone around my sockets highest reading 0.41 is tis my R1+R2 or am I missing something and is R2 just measurment from cpc at cu to wurthest point on ring main ie half way please help
on top of this is the max disconnection time for tt 0.2sec found that in the regs

thought r1 and rn should be about the same might be clip not tight enough
please help
Thanks

 

[electricAl]

Before you delve any further into calculating r1 + r2 / 4 you NEED to have your r1 & rn continuity readings equal (or very close)

I`d suggest you tighten that clip etc & start at the start again mate

 

[Guest123]

Agreed.

Seems like the problem is on the neutral, double check all connections and re-test.

Your R1+R2 is correct, as is your R2 theory.

 

[piz]

ok check this one out kitchen sockets r1=0.12 rn=0.12 r2=0.21 better readings only 3 sockets on the ring but R1+R2=0.62 why??

Thanks lenny half scared dont like ring testing try to avoid but need to practise

 

[Spudnik]

How do you test kitchen circuits when you have installed them?

Not being funny, but i am a little concerned that you are rewiring some ones house and have little understanding of the most important part of an installation.

 

[electricAl]

I share the same concerns (altho it must be said, Piz is hardly alone is he?!?)

ok check this one out kitchen sockets r1=0.12 rn=0.12 r2=0.21 better readings only 3 sockets on the ring but R1+R2=0.62 why??

Thanks lenny half scared dont like ring testing try to avoid but need to practise

Jason`s valid point aside, if we`re to help you to improve your technical knowledge Piz, please ensure you`ve cross connected the T&E correctly - as in L1>E2 & L2>E1

If you haven`t you`re simply not gonna get what you expect - readings will be all over the shop.

& you really shouldn`t be `scared` - you have isolated first haven`t you

 

[Spudnik]

Indeed and we all have to start somewhere.

However, testing is not something that can be learned over a forum!

 

[electricAl]

Indeed and we all have to start somewhere.

However, testing is not something that can be learned over a forum!

A very good point.

I am gratefull of your wisdom o` great one.

Standing aside...

 

[piz]

Hi Jason

reply tom your answer

r1 rn r2 end to end continuity

step 2
cross connect ph and net take readings should be r1+rn/4 approx

step3
cross connect
ph and cpc
check sockets should be approx r1+r2/4

then ins rest polarity ze pfc rcd etc


radial connect cpc and live at cu then test cpc and live at socket light etc

hope this makes sense
been a long day just cant understand if its the highest of step 2 or step3 we record
hope this makes sense let me know if you wouldnt do it like this

 

[Spudnik]

No need to stand aside.

I would rather people help than let someone cause themselves or someone else harm.

I was merely voicing my concerns and was not meant to offend or stop anyone giving advice.


Had a bad day


Edit:

piz

You record values of r1, rn & r2 end to end.

these tests are for RFC ONLY.

R1 + R2 is for all circuits.

Cross connecting r1 & r2 gives you your R1 & R2 values.

So its step 2 thats recorded

 

[piz]

sorry dont mean to upset anyone just wanted to prove I had a good idea how to do it think you find it looks ok I know spelling aint right and tests aint in order but thy would you be so concerned

 

[Spudnik]

sorry dont mean to upset anyone just wanted to prove I had a good idea how to do it think you find it looks ok I know spelling aint right and tests aint in order but thy would you be so concerned

You havent upset anyone (yet ).

Testing of any circuit should be done and understood before they are energised.

Also, r1 & r2 are very different to R1 & R2, so spelling, in this instance does matter.

 

[piz]

Yeah your right will leave the wine alone have another go in the morning and let you know
cheers

 

[Spudnik]

No probs bud.

Be safe.

 

[baldsparkies]

Although 16th edition testing, this link is still a good read.
Piz at least your not putting your breakers on and waiting for the bang. Be professional about it (Always use a broom stick)

http://www.tlc-direct.co.uk/Book/8.1.1.htm

 

[Mr Mark Sparks]

hey piz
treat yourself it has all you need to know about testing and is worth a read
[ame=http://www.amazon.co.uk/exec/obidos/ASIN/0863418570/interactiveda3371-21]Guidance Note 3: Inspection and Testing Guidance Notes for Bs 7671: Jon Elliot: Amazon.co.uk: Books[/ame]

 

[piz]

Got it aint read it for years
yellow book isbn 0-85296-991-0
must be ok ish passed the 2391 testing side of it but was about 5 yrs ago
is there a later edition ie 17th