Radial Circuit testing

[L Plate]

Evening all,

Can anyone give me some idea please... I am aware that there is 4 steps on doing the ring final circuit test ( dead test )

1) line to line / N to N and cpc to cpc

2) line to neutral crossed connected ( both legs )

3) Use the socket plug tester and check the socket one by one and note the reading

4 ) Line and cpc crossed connected ( both legs ) , record the highest reading

>>> My question is > I am not so sure if i am doing the same way on radial circuit ??

any help pls....

evening all

 

[SLIPSHOD & SLAPDASH]

Just link the furthest end of the circuit together. Line to Cpc is your R1 +R2

 

[L Plate]

Just link the furthest end of the circuit together. Line to Cpc is your R1 +R2

Thank you Slip,

on my drawing ,

http://www.talk.electricianforum.co.uk/attachment.php?attachmentid=635&d=12731810

should I linked the L and CPC ? on socket no. 3? and do the test in the CU is it right ?? please correct me sir if I'm wrong

thank you

 

[Apache]

Thank you Slip, on my drawing ,

http://www.talk.electricianforum.co.uk/attachment.php?attachmentid=635&d=12731810

should I linked the L and CPC ? on socket no. 3? and do the test in the CU is it right ?? please correct me sir if I'm wrong

thank you

do the twin sockets want to be diagrammatically bigger than the single socket spur? They all seem the same size.

 

[L Plate]

do the twin sockets want to be diagrammatically bigger than the single socket spur? They all seem the same size.

Ok , I will re draw it .. thank you

 

[SLIPSHOD & SLAPDASH]

The correct answer is to test at both socket no3 & the single socket spur, as the cpc could be lost/broken at either. In this scenario it would be easier to link the line to the earth bar in the consumer unit and then test at both furthest ends. When you come to do any live tests such as the Zs then you test all outlets and record the highest reading, which should be the longest cable run away from the board.

If you want to be clever and get extra points you could mention that the sockets should most likely have 30mA Rcd protection i

 

[L Plate]

The correct answer is to test at both socket no3 & the single socket spur, as the cpc could be lost/broken at either. In this scenario it would be easier to link the line to the earth bar in the consumer unit and then test at both furthest ends. When you come to do any live tests such as the Zs then you test all outlets and record the highest reading, which should be the longest cable run away from the board.If you want to be clever and get extra points you could mention that the sockets should most likely have 30mA Rcd protection i

Thanks again Slip>>> I got it and I do understand your explanation , the RCD rating that has given to us is only 20A , please if you don't mind to support why it should be 30A instead of 20A.

thanks again Sir

 

[SLIPSHOD & SLAPDASH]

No no no, Its ok to have a 20A radial circuit. 13a sockets should also be protected by a 30mA RCD unless under supervision ( i think a silly rule) Also cables buried less than 50mm & not in an earthed metalic enclosure (Not the case here) also have to be protected by a 30mA Rcd

 

[L Plate]

No no no, Its ok to have a 20A radial circuit. 13a sockets should also be protected by a 30mA RCD unless under supervision ( i think a silly rule) Also cables buried less than 50mm & not in an earthed metalic enclosure (Not the case here) also have to be protected by a 30mA Rcd

got it Sir,

now I can sleep well and not thingking too much on my coming exam, at least I have some ideas now .. this is really a big help for me ..

thank you again and to all who were so helpful ...

evening all

 

[androiduk2002]

Thanks again Slip>>> I got it and I do understand your explanation , the RCD rating that has given to us is only 20A , please if you don't mind to support why it should be 30A instead of 20A.thanks again Sir

Hey L plate,

A 20A breaker with 2.5mm T&E as per your drawing is an A3 radial which means a maximum floor area of 50 mtrs squared maybe served.

You can have a 32A breaker as an A2 radial but this has to be wired in 4mm T&E but this covers a maximum floor area of 75 mtrs .

For over 75 squared mtrs there is the ring main: maximum floor area of 100 square mtrs wired in 2.5mm T&E and rated at 32A breaker.

Hope this makes it a bit clearer for you buddy.

 

[paul b b]

Hey L plate,A 20A breaker with 2.5mm T&E as per your drawing is an A3 radial which means a maximum floor area of 50 mtrs squared maybe served.

You can have a 32A breaker as an A2 radial but this has to be wired in 4mm T&E but this covers a maximum floor area of 75 mtrs .

For over 75 squared mtrs there is the ring main: maximum floor area of 100 square mtrs wired in 2.5mm T&E and rated at 32A breaker.

Hope this makes it a bit clearer for you buddy.

but this would be a ring circuit not a radial ( by making it circuit into a ring you are in affect making the cable double the size so 2.5mm2 becomes 5mm2, enabling the cable to take 32A)

 

[L Plate]

Hey L plate,A 20A breaker with 2.5mm T&E as per your drawing is an A3 radial which means a maximum floor area of 50 mtrs squared maybe served.

You can have a 32A breaker as an A2 radial but this has to be wired in 4mm T&E but this covers a maximum floor area of 75 mtrs .

For over 75 squared mtrs there is the ring main: maximum floor area of 100 square mtrs wired in 2.5mm T&E and rated at 32A breaker.

Hope this makes it a bit clearer for you buddy.

Thanks Andro... I now understand that using the RCD will also depend on the lenght of the cable as well ( and load capacity ? ) , so its clear to me now with the help of OSG as well,..

thanks again for the info.

 

[NozSpark]

Duing my assesment I was asked how I would proove polarity on a radial circuit..

What he was after was doing a RN+R2 test after the R1+R2 test!!.... should get the same result for a socket radial

 

[SLIPSHOD & SLAPDASH]

Why is a R1+R2 test any more or less a polarity test than R2+RN ?

 

[NozSpark]

Well individually neither of them are really, but together......

 

[sparkytim]

If you have proved that the L is L AND NOT N and the N IS NOT CPC then N must be N, (this is the R1+R2 TEST)

That is all that is needed.

 

[SLIPSHOD & SLAPDASH]

I still cant see how that proves polarity any more than any single test, it proves continuity. Maybe its because when i was taught many years ago, the tests we have to do now had not been thought of, and the loop tester not invented (well not for this type of work). I still megger the cables clear, then L-E, then N-E.

 

[ADS]

I still cant see how that proves polarity any more than any single test, it proves continuity. Maybe its because when i was taught many years ago, the tests we have to do now had not been thought of, and the loop tester not invented (well not for this type of work). I still megger the cables clear, then L-E, then N-E.

As with a ring final, you prove polarity by doing R1 + RN followed by R1 + R2.

There is nothing wrong with doing the exact same tests on a socket radial as you do on a ring final, and test at each socket.

R1 + R2 on it's own doesn't prove polarity on a socket outlet,(even if you throw the switch), because you could have a Line - Earth reversal

 

[NozSpark]

As with a ring final, you prove polarity by doing R1 + RN followed by R1 + R2.There is nothing wrong with doing the exact same tests on a socket radial as you do on a ring final, and test at each socket.

R1 + R2 on it's own doesn't prove polarity on a socket outlet,(even if you throw the switch), because you could have a Line - Earth reversal

Exactly

 

[sparky999]

Some good points noz and ADS i will keep this in mind now.