2.5mm or 4mm extended ring

[scoobydoowantsu]

I'm sorry, that last message may have sounded a bit arsey.
Wasnt my intention.

So, if i cant perform the test, is checking the CU for a single or 2 red wires to that circuit good enough?
simon

 

[1john]

What makes you say that the cable is 4.0mm? Is it because it is multi stranded?, if so, is the CPC (earth) wire stranded, if so, are there 3 strands, if this is a 70's house this could be a rind final circuit constructed with 7/.029 cable (imperial cable)

 

[scoobydoowantsu]

I didnt measure the insitu cable, i was just pi##ed off that i'd bought 2.5mm and then saw the cable was bigger.
I will check in the morning when i return to the house.
But it is white cable not grey like i have purchased, I am just checking prices of the multimeter so i can check continuity as well.

 

[1john]

You can get a cheapy for about a tenner mate and it really is the best investment a DIYer can make for doing electrical work without a doubt! Anyone doing electrics should have one!

 

[scoobydoowantsu]

Thanks 1john, i will get one.

But, what am i checking for?

And what part am i checking?

 

[1john]

You want to verify that what you have is infact a ring final circuit, you will need to verify this by taking some readings on the various cables with the electricity turned OFF!!

 

[scoobydoowantsu]

Thanks, I have read already that the power needs to be off.
But, once i find the correct terminals, what am i testing for and what readings should i get.
And once i have tested, where does that leave me with creating my ring around the room?

Sorry if im asking too much, and boring all your educated electricians, but I want to do this right.
thank you.

 

[scoobydoowantsu]

I will have to take my laptop with me tomorrow so that i can follow all your brilliant much appreciated advice.

might even have to call one or two of you.

simon

 

[ban-all-sheds]

So, if i cant perform the test, is checking the CU for a single or 2 red wires to that circuit good enough?
simon

Sadly no - sometimes people connect each end of the ring into 2 different breakers.

Lord knows why - dropped on their heads as babies, I guess.

Or you could have a radial circuit which branches off at the breaker.


First step though is to open the CU and see how many conductors are in the breaker for that circuit.

 

[davelx]

We are trying to determine if the circuit is a radial or ring and continuity test will help us do that.
You can run a fused spur without splitting the circuit, but I would try to extend it.
If it was a radial circuit you can find the end socket on the circuit and just extend from there if it is suitably located. if it's a ring we need to break in to it!
You can split the sockets in to double outlets!

If it's a radial you can extend from any point but you'll need to use the same size cable if you want to put more than one socket outlet on the extension.

 

[PrenticeBoyofDerry]

If it's a radial you can extend from any point but you'll need to use the same size cable if you want to put more than one socket outlet on the extension.

You'd have to put the same size cable in, if you was adding just one socket-outlet and extending circuit!

 

[electronicsuk]

But, once i find the correct terminals, what am i testing for and what readings should i get.

With the power turned off and after testing to ensure that the circuit has been properly isolated, you can then remove the faceplate of the socket you want to extend from in the bedroom. Using the multimeter with the probes in the COM and V/Ω sockets and set to the 200Ω range, you can proceed to test between the two neutral conductors, then the two line conductors, then the two CPCs/earths. If the circuit is a ring then you should expect to see a low reading, let's say an ohm or two, between all the conductor pairs.

The above isn't a foolproof way to test for the presence of a ring final circuit, as if the circuit has been tampered with by an incompetent in the past, you could well end up with all sorts of strange circuit arrangements. If the wiring is original then this isn't so likely to be an issue.

And once i have tested, where does that leave me with creating my ring around the room?

Best leave that until you complete your tests.

 

[1john]

blimey, when i started reading that post from electonicsuk, i was half expecting to start reading about taking a line from one leg and joining it to the cpc from the other leg..... the resistance difference regarding the line and neutral loops compared to the cpc loop should be 1.6666666 and all the other stuff that goes with testing a ring final circuit. One good reason for me to prefere a radial circuit!

 

[scoobydoowantsu]

well guys, its been enilighting.
And I appreciate everyones time and input.
Turns out she had a friend round today that was an electrician, so i explained what i was going to do and he said it was fine.
It turns out that its a ring.
The insitu cable was imperial.
And 2.5mm was correct to use.
The original wiring was unmolested.
So from one double socket she now has 2 singles and 4 doubles and a ring around the bedroom.
I'll be back, as I always have more to learn.
thank you.
My next question will be in painting masonary, namely pebble dash, urgh!!!

 

[PrenticeBoyofDerry]

a ring around the bedroom.

Sounds like a nursery rhyme!
glad it's sorted!