How to check if a fuse feeds a ring final or 2 radial circuit

[247 handyman]

Hi guys. I need to check if I have a ring or 2 radial running from a fuse. I have an old wylex fuse box in which someone has put a blue 15amp fuse in a red 30amp carrier.
If I disconnect the 2 cables and check for continuity of the 2 lines then the 2 neutrals will this tell me if I have a ring or am I missing something ?

Thanks in advance guys

 

[kingeri]

It's not that simple mate, checking for continuity in that way will only prove that the two legs are interconnected at some point. They could be joined half way along but not be a ring. There is a specific test for this, but it is not something a none-spark should really be doing. I assume you are not a spark, judging by the question. Do you have an MFT?

 

[westward10]

Agree with above and you show you have no electrical qualifications. It would be a routine test for an electrician then you can fit the correct fuse and shield.

 

[247 handyman]

It's not that simple mate, checking for continuity in that way will only prove that the two legs are interconnected at some point. They could be joined half way along but not be a ring. There is a specific test for this, but it is not something a none-spark should really be doing. I assume you are not a spark, judging by the question. Do you have an MFT?

Thanks for the reply.
Your right pal I'm not a spark but I'm not a numpty either if you know what I mean. Yes I do have a multi meter. In your opinion is it something I can do with the help of good people like yourself ?
For reference this is not for a job but just to help my pensioner in laws out as it appears someone has, like I said, put a 15a fuse into a 30a carrier. I just want to sort it for them so they don't lose all sockets as they currently have done 4 times in the last 3 weeks.
Thanks for any constructive advice I really do appreciate it.

 

[kingeri]

To verify if it is a ring, you need to access every socket outlet on the circuit in turn (you will likely have to unscrew them all), after making temporary connections in the CU. You also need to know how to interpret the results obtained from your 'multi meter'.

 

[westward10]

You really need a continuity tester and whilst I understand wanting to help the in laws the circuit needs correct testing and it would be difficult to give instructions to a non qualified person without the correct meter.

 

[247 handyman]

Is this the test of resistance
L to L
N to N
E to E
Then cross connect L1 to L2 etc and check at the sockets
You tube is great for instruction videos

 

[Pete999]

Thanks for the reply.
Your right pal I'm not a spark but I'm not a numpty either if you know what I mean. Yes I do have a multi meter. In your opinion is it something I can do with the help of good people like yourself ?
For reference this is not for a job but just to help my pensioner in laws out as it appears someone has, like I said, put a 15a fuse into a 30a carrier. I just want to sort it for them so they don't lose all sockets as they currently have done 4 times in the last 3 weeks.
Thanks for any constructive advice I really do appreciate it.

 

[Midwest]

You tube is great for instruction videos

Why bother coming here then, when you think you can trust You Tube?

 

[247 handyman]

For advice as to suitability of the test. I rather hear from someone who does the job than a teacher who may have all the gear and no idea. Their is no substitute for real life experience

 

[kingeri]

For advice as to suitability of the test. I rather hear from someone who does the job than a teacher who may have all the gear and no idea. Their is no substitute for real life experience

....of which you have absolutely none in this instance.

 

[247 handyman]

Thanks for your reply
If I follow this would this give me the knowledge that it is indeed a ring final so I can put a 30a fuse in the red carrier

 

[Pete999]

Why bother coming here then, when you think you can trust You Tube?

Just trying to show the OP the complexity, of a RFC test and the need for the correct equipment, a multimeter is no good for this test, not something for what is a DIYer or in this case a Handy man, who in all honesty shouldn't be fluffing around with something he has very limited knowledge, these videos are very informative for trainees etc, absolutely not to be used by non sparkies

 

[247 handyman]

Thanks guys for the advice and constructive criticism. I guess they will just have to wait a bit longer for the brother in laws electrician to turn up. They've already waited 3 weeks as he's busy.

Thanks again guys

 

[247 handyman]

....of which you have absolutely none in this instance.

Correct which is why I asked the professionals who do have the experience for advice which I have duly taken.

Thanks again guys

 

[kingeri]

Great news that you've made the right decision mate!

 

[247 handyman]

Yeah like I said I was just trying to help. I had to talk my brother in law out of just changing the fuse without getting it tested.

 

[kingeri]

Yeah like I said I was just trying to help. I had to talk my brother in law out of just changing the fuse without getting it tested.

That was very wise. You seem like a chap with lots of common sense!

 

[Pat H]

For clarity most multimeters don't offer a low enough continuity reading. To know the arrangement of the wiring we need to measure to fractions of an ohm reliably. Based on the readings we can then calculate the location of each point in the circuit based on the resistance. Most general millimetres just don't offer a low enough or consistent enough reading.

Sorry I can't offer more help and as you say there is a lot of information on google and you tube. Some very helpful people post detailed information on testing and procedures on the understanding the viewers are adults and able to judge what they are capable of or not but that its better they know than to not tell.
That doesn't seem to be the "style" of this forum where qualified experienced people can get help otherwise you will be referred to an electrician.

 

[HandySparks]

I was thinking about this recently. I don't think that the cross-connection method is particularly reliable for checking the configuration of a ring circuit where you have, for example a very short spur with more than one socket, where the additional resistance produced is minimal.

I came up with the following as a method that doesn't rely on detecting small changes in resistance:

Identify all the sockets and other accessories on the circuit.
Disconnect both ends of the line at the board and connect a resistance meter or a continuity tester across the ends.
At each accessory, disconnect the line and check that continuity at the board is lost. Then re-connect.
If breaking the connection at every accessory also breaks the ring, as indicated at the board, then you have a single, complete ring with no spurs and no cross connection.
Repeat for neutral and cpc if thought necessary (depending on wiring method).

Obviously measure ring continuity, IR, Zs, etc. as usual.

Thoughts?