Ring circuit?

[vad25]

Hello all!

Have been changed CU for assessment. When tested ring circuit (s/o) it wasn't continuity at all. Somebody disconnected wire when been moving sockets.

So I've left it as radial, it is 4smm cable with 1,5smm cpc,32A mcb,R1+R2 0,95,

ZS 1,01. Everything looks OK. I've disconnected returning cable it's really died.

How do you think, is it all right and what shall I write to EIC. If it is wrong any advice please.

 

[Bez]

If you're asking is a 4mm radial ok, then the answer would be yes, but from what you describe I would do some further investigation of where this other leg of the old ring goes/comes from. Does it still feed any other sockets?

From what you say if it's wired in 4mm, it sounds like 2 radials off the same breaker. (Unusual for a ring to be wired in 4mm)

Get your meter out and have a thorough look at the circuits.

 

[vad25]

If you're asking is a 4mm radial ok, then the answer would be yes, but from what you describe I would do some further investigation of where this other leg of the old ring goes/comes from. Does it still feed any other sockets?From what you say if it's wired in 4mm, it sounds like 2 radials off the same breaker. (Unusual for a ring to be wired in 4mm)

Get your meter out and have a thorough look at the circuits.

Thank you Bez. I've written before, other side of ring has been disconnected somewhere under plaster( no any joints available) and I've disconnected it from mcb as well. I don't know how to describe this work in EIC.

Thank you again!

 

[green-hornet]

R1+R2 0,95,

ZS 1,01.

Look very high readings to me for a 4mm radial.

I would investigate further, are you sure its 4mm and not imperial sizes?

 

[PC Electrics]

Vad,

You give no indication of how old this installation is?

You sure it's 4.0/1.5 t&e you've got there?

Could it possibly be old imperial cable, say 7/029 conductors with a 1/044 cpc? It was common for rings on a 30A 3036 to be wired in 7/029.

Measure the diameter of the single strands and use the table from the thread below to identify the cable.

As Bez says it would be very unusual for a ring to have been wired in 4mm in a house.

From your profile it appears you are from Russia - so you could be forgiven for for being unaware of the use of imperial cable into the '70s here. However, if you're doing CU changes then it's something you'll come across often and so need to be able to identify the cable to assess the circuits adequacy (note, in this instance if the cable is 7/029 then it is not adequate on a 32A mcb and needs to be on a 20 or 25 or restored to being a ring).

http://www.talk.electricianforum.co.uk/showthread.php?t=7583

http://www.screwfix.com/prods/36839/Hand-Tools/Measuring/Calipers-Micrometers/Hilka-Pro-Craft-Micrometer

 

[PC Electrics]

Great minds eh, Green?

 

[green-hornet]

Good answer and better than mine

Just looking at the test figures made me suspect it was not 4mm.

 

[PC Electrics]

Vad,

Got any feedback for us?

 

[vad25]

Vad,Got any feedback for us?

I'm going solve this problem Friday

 

[Apache]

I'm going solve this problem Friday

That's the spirit!

 

[vad25]

Thank you for your advices.

It was very useful lesson for me.

Cable's 7/029 and CPS 1/044 so I've installed type B mcb 20A.

But with one size shall I write to schedule of test result(Imperial or metric)

Thank you again.

 

[ianmacd]

The smallest.

 

[PC Electrics]

If the circuit contains only imperial cable (7/029 & 1/044) then put these figures in the relevant boxes on your EIC.

If the circuit also contains some metric cable (2.5 & 1.5), then put 2.5 for the conductor size and 1/044 for the cpc size (ie the smallest respective conductor sizes) AND make a note in the comments column that the circuit contains a mix of imperial and metric cables.