we all know that one of the guaranteed ways to trigger Gary is to call the circuit that we put
sockets on a ring main it should more accurately be called a ring final circuit because ring main
is a reference to the way transformers are connected together on the distribution network
but whatever you call them and however you feel about them there must be millions of them in place
around the UK and people are still installing them now and as we all know testing them properly can
be a little bit of a pain you need to do your end-to-end test calculate your expected R1 plus
R2 value then interconnect the line and neutral conductors and go around the circuit checking at
every point then come back and interconnect the line in protective conductors and then go back
off again around the circuit testing at every point to prove the circuit is healthy all the
while juggling numbers in your head and trying to keep track of the figures it's a nuisance to say
the least and like myself you may have wondered to yourself as you were working your way around yet
another ring final circuit if only there was an easier way to do this well there is it's this the
A2214 ring continuity adapter from Metrel and i'm going to demonstrate to you now how it works using
the MI3155 and i'm sure you'll agree that this is a game changer for ring final circuit testing
you'll notice having laid this out neatly that there's four pairs of wires the first pair which
are both black goes off to the Metrel connector so we'll connect that to the tester when we start
the testing process then we've got three pairs of black and red with color-coded connectors on
the end these being green for connecting to the CPC blue for the neutral and of course brown for
the connections to the line conductors now we can connect either crocodile clips to these or probes
but as you'll see in a moment we're about to leave this connected up while we wander off around the
house testing the sockets so croc clips are the best bet i've been sent these ones by our studios
in the north and as you can see i've got two of these which are brown so they're going to go
onto there which is really handy i've also got two which are blue in color so they're going to go
onto those for the neutral connection and i've also got one green and two black which is in no
way messing with my ocd which is absolutely great the person responsible for this shall
remain Gordon nameless sorry shall remain nameless we'll just have to use the black ones for the CPC
connection on this occasion okay so the first thing that we need to do is we need to null out
the leads on the ring continuity adapter so we're going to plug it into the top of the Metrel MI3155
to start with and then we just clip all of the leads to their relevant colours so here we're
going to connect the line conductor connectors together and it's important when we do that we
put them solid jaw to solid jaw so we're not going to put them like that we're going to put them like
that and that then allows the best connection to be made and will get us the most accurate reading
so then we'll do the same for the CPC connections and then for the neutral connections as well
and then we turn on the ring continuity adapter so we get that red light on there
and then you'll find this test if we just come out of this menu in the single tests menu so you
can see it's in single tests then you press r low and then you select the ring continuity test now
it may be worth noting at this point if you can't find this option on your MI 3155 you may need a
firmware upgrade and that's really simply done if you contact Metrel they'll send you the relevant
information and i managed to do it so it's pretty straightforward there so we've got those connected
and then we press this button here it's showing us at the minute that this is not calibrated
pressing that button takes us into the calibration menu and what it's doing now is it's just checking
the resistance of those leads and making sure that we're going to get a good reading so that's
now set those leads to a value of zero and we're ready to start the actual test okay so this is
the consume unit that we're going to demonstrate this on you can see i've got it switched off and
safely isolated although the incoming meter tails are still live but there's no lockable isolator
further upstream from here so for me i'm quite happy with the the level of risk involved here
and the level of safety but of course if you do something a little bit differently
then please do let me know in the comments below i know i can lock this room and control the key
for that lock so no one's going to come in and accidentally poke anything in there and i'm not
going to stick my fingers in there because it's IP2X so i'm not going to access those terminals
but as i say if you've got additional measures you take please feel free to comment those below
and if you're interested in safe isolation and how to achieve it please check out our free training
package over on the know how page of efixx.co.uk or by clicking a link in the description below but
enough of that let's get on to the tests so this is where the ring continuity adapter really comes
into its own because we've got the option up here you can see this is the ring final circuit that
i've split into the two legs so that's one leg at the top there and that's one leg at the bottom and
because we've got these color-coded leads on here what that means is that i can actually connect
onto the the correct leads so i'm going to put all of the black conductors to the leg that i've moved
to the top of the board there so they're going to go at the top and all of the red ones will go at
the bottom so you can see here i've got the green probes here which are connecting onto the CPCs
so again we'll get the black neutral lead and put that onto the neutral at the top
and then we'll get the red one and put that onto the neutral at the bottom if we can find our way
to it there and then we've also got the red line conductor which will go on to the bottom terminal
and then the black line lead which will go onto the red one at the top there so that's all good
so now if i just move these wires off the front of the tester there and make sure that we've got
the ring continuity adapter switched on you can see that now we're in a position where we can
just press the test button and do the test and what this is going to do it's going to measure our
end to end values for us so we can either hit the run button or the play button on the touch screen
and what that's doing now is it's measuring the resistance of those conductors and it's going to
return a value to us for those end to end values so we've got r1 as 0.47 rn which is the neutral at
0.47 so that's the line and the neutral conductors are the same value which you'd expect them to be
because they're the same size conductors and then we've got r2 at 0.8 ohms and that's higher
because the cross-sectional area of the CPC is smaller meaning that it's got a higher resistance
okay so now we've got that hooked up what we're actually going to do now is we're going to unplug
the tester from the ring continuity adapter and then we're going to go out and do some testing
but not before we've done one more step of zeroing a lead let's do that now okay so in a moment we're
going to go off and test at the sockets so what we'll need to do is change the test parameter now
to R1 plus Rn and R1 plus R2 so you can see that we're now going into the next phase of the test
so that's all good so we're happy with that you can see down the bottom here now we're going into
a different test mode and it's actually done the calculation here for us for the expected
reading so can you see there it's done r1 plus rn divided by 4 which gives us 0.23
and here we've done r1 plus r2 divided by 4 which is 0.32 so these
are the readings that we should be getting as we go around to each individual socket and test
of course this if we get one reading that's quite a lot higher than the others then we
know that we've got pretty much uh a nailed on spur and then if we find another one sort of
somewhere in the locality of that one that's even higher it's likely we've got a spur off a spare
so that would obviously lead some problems but can you see that we've gone back to a calibration
with an x there so what we need to do now is we need to calibrate the test lead that we'll
be plugging in to each individual socket so again we just connect this into the top here
so we've plugged that into the connector at the top of the material and then on the front of the
ring continuity adapter we're just going to leave this hooked up as it was in the previous step
but on the front there's this socket so if i just move that cable out the way you can see that there
and that is just a shorting socket that is going to allow for the calibration so there's
no connection inside the test unit between that socket and those leads it's just simply here as a
calibration point to set this lead to zero now mitre also do another version of this that's
just a standalone little uni but of course it's built into this one so we'll just plug this in
here so we'll plug that into there like that and then again press the calibrating button
and that's now just setting the resistance of that test lead to zero you could see there that
we would have been getting 0.22 added onto all of our readings but now that's set to zero so
now we can unplug this from here and then we can go out to the rest of the circuit and we can start
testing at the individual points so let's go and do that now for this next stage you can either use
leads plugged in here with probes attached which can be handy if you're measuring to an accessory
wired off the ring such as a fan or something like that or you can use a lead with a plug already
connected for normal socket outlets obviously if you're going to change the connection method that
you're making then you need to re-zero your conductors to make sure that you're getting
accurate readings now one of the really clever things about this device is that you only need
to go to each socket once so if we plug in there and then hit the run button you can see there
that's going to do the test and back at the mains where we've got the connection made that little
adapter there actually changes the connection between line and neutral and then line and CPC
and the tester will then test between line and neutral and test between line and CPC so all of
those interconnections that you'd have to keep going backwards and forwards to the board from
are all done by that test adapter that we've left there and now we only need to do the test once at
each socket and we've got our readings you can see they're not 0.22 and 0.33 so let's just plug into
another socket over here and check what readings we're getting make sure that we're switched on
hit the play button for the next one so you can either hit the run button or the little
play button here and it'll carry out all those tests again at the next socket outlet
and hopefully you can see there we're getting similar readings to what we had before
and we can also compare them down here with our expected readings that we calculated and you can
see they're pretty close what you might find is that the line and CPC one does change a little bit
as you go around the circuit because the CPC has a smaller cross-sectional area which does kind of
affect the readings if you've ever wondered about this divide by four function and why we do that
bit of the calculation while we divide by four to find the reading that we get when we cross connect
then watch out for a Q and A video that we've made on this that helps to explain that with a kind of
a physical demonstration of what we're doing so you can see how that works
so there we go now it's just a matter of carrying around the circuit and finding our readings and if
there's anything suspicious we'll find it so there we go that's the Metrel ring continuity adapter
i think it's just brilliant and another one of those products that i just wish had been around
20 some years ago because it definitely makes electricians lives easier and we like that at
eFIXX now if you're interested in ring final circuits in general then please do go and
check out our free training package that we've made on this subject to help you with your cpd
you'll find that in the link below or over on the know-how page of efixx.co.uk
but as always we want to hear from you will this be on your to buy list moving forward
do you think we'll see ring final circuits being installed for a long time to come
or do you think that perhaps they've had their day whatever your thoughts whatever your questions
please leave them in the comments section below and as always thank you very much for watching