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Discuss Testing.. IM A LEARNER!! in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

T

TPES

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Hi all

I'm being taught testing at college, every practical piece of work we do we have to test.

I have brought my own all in 1 metrel tester.

I have decided to put what ive learnt at college to the "test" and test my own install at home.

I have 2 ring mains in my house split front and rear.

I am measuring continuity of the front ring.

End to end...

R1 = 0.34
RN = 0.34
R2 = 0.59

Now i have crossed linked my line and neutrals at the board ready to take a resistance reading at each socket n the ring, as i have been taught too at college.

Reading at each socket so far front (downstairs) are...

0.17, 0.16, 0.15, 0.15, 0.17, ohms. I have now gone upstairs to continue the test at the remaining sockets on the front ring, the first socket i came to read 0.37 and the next was 0.41 ???????

Now i know that checking continuity of a ring the readings should not be more than .05 in differnce between each socket.

So why am i getting such a big difference in my readings do you think??

This may be very obvious to many of you and there is prob a very simple answer.

I want to learn as much as i can about testing and aprreciate if i can come to you guys for guidence no matter how simple my questions may be.
 
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C

coxy

  • Thread Starter Thread Starter
  • #2
Hi Magic,
Likely to be spurs,
Even if you have 2 cables at these sockets does not mean a ring main.If in doubt at the high reading sockets test for a ring,if no ring they could be spurs from some socket.
 
T

TPES

  • Thread Starter Thread Starter
  • #3
Hi yes thats the first thing they told us at college that a high reading is likely to be a spur. But my house is only 2 years old, a new build jelson home, and as i have wired many new builds for different builders i think it is very unlikely there would be random spurs off a ring.
 
R

red

  • Thread Starter Thread Starter
  • #4
I wouldnt count out what coxy said........I heard of one very well known developer that were wiring upstairs sockets on a ring final and just dropping a spur down from each socket to all of the downstairs sockets. Anything to save a few quid!

Not sure if i read your post right but what about the length of the cable? The reading will be high if it is to long.
 
T

TPES

  • Thread Starter Thread Starter
  • #5
There is a 2 cables at each socket upstairs, infact on the whole front ring, The only time we would spur up to other sockets is on a 3 story house spuring upto a few sockets in bedrooms on top floor.

But my house is a very small 2 bed semi, with only about 8 sockets on the front ring. there wouldnt be much cable length in this ring at all.


"Not sure if i read your post right but what about the length of the cable? The reading will be high if it is to long."

Am i wrong in thinking that what ever size the ring there sholdnt be more than .05 in difference at each outlet? or is that wrong
 
Last edited by a moderator:
C

coxy

  • Thread Starter Thread Starter
  • #6
Hi Magic when you test at the sockets where are you doing it - through the pins or undoing the socket and testing at the terminals - i have known to get different readings by just sticking the probes in the socket pins.Again, see if you are getting a ring at these sockets,and the results match.It is possible to wire a ring within a ring with a spur.Unlikely but with house builders anything possible.You say you have 2 rings is the other ok ?
 
T

TPES

  • Thread Starter Thread Starter
  • #7
Im using a socket tester, my test leads are going stright into it. saves me taking each socket off.
I have not tested the other ring yet, ill prob do that tomorrow.

(the misses came back from shopping and was moaning at me there was no power for her to do anything, So had to juice back up... Women!)
 
W

WarrenG

  • Thread Starter Thread Starter
  • #8
Magic-sid,

I know this may seem a silly question, but it does seem a little strange that you have a front and rear ring?

Generally there is one up and one down?

My first though was that you need to swap the legs you are crossing over i.e. P1-N2, P2-N1 from possibily P1 - N1? because this usually indiates readings going up towards the centre of the ring.

I would check you have the right legs?
 
T

TPES

  • Thread Starter Thread Starter
  • #9
Yeah odd but i have known many new builds wired front and back instead of up and down.
Im very sure i had the correct legs connected. I will retest again and see if i get the same readings, although i did do it 3 times. I may have made the mistake.

Do my readings look like they could be right, I'm new to testing so have no other test to compare these readings too.

Thanks
 
W

WarrenG

  • Thread Starter Thread Starter
  • #10
Magic-sid

Readings can really vary obviously due to length etc. If you PM me I have a good book in pdf format that I could send to you which will help you with your testing?

Warren
 
W

WarrenG

  • Thread Starter Thread Starter
  • #11
Hi Guys,

The book I mention in my previous post can be downloaded here:

RapidShare: Easy Filehosting

Follow Link
Click on Free User
Wait for seconds to count down & your download save box will appear.

Hope this helps!

PS (for AOL users use Internet Explorer to Download)
 
T

TPES

  • Thread Starter Thread Starter
  • #12
Thanks very much Mr G!! I have it now..

Appreciate it.
 
T

TPES

  • Thread Starter Thread Starter
  • #14
Hi Guys,

The book I mention in my previous post can be downloaded here:

RapidShare: Easy Filehosting

Follow Link
Click on Free User
Wait for seconds to count down & your download save box will appear.

Hope this helps!

PS (for AOL users use Internet Explorer to Download)

This is the "Dogs ***"..
Anyone who does not have many text books on Inspection and Testing DOWNLOAD THIS NOW!

My laser printer is about to get some serious abuse!
 
Last edited by a moderator:
T

TPES

  • Thread Starter Thread Starter
  • #15
"0.17, 0.16, 0.15, 0.15, 0.17, ohms. I have now gone upstairs to continue the test at the remaining sockets on the front ring, the first socket i came to read 0.37 and the next was 0.41 ???????"


It was Brushed Stainless sockets that seemed to make a difference!!!!!

I have no idea How or why this makes a difference, Where the front ring continue's upstairs the sockets in the bedroom are brushed stainless fronts. when i plug in my kewtech Socket adapter (as i did downstairs with the white mould sockets) The reading is higher..

I took the socket off and put my test probes on the actual terminations, This then took a reading of 0.18 & 0.19 to then make it 0.05 within the rest of the sockets readings.
 

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