no continuity on live?

[1878]

alright fellas,

in college still but i'm fine at everything apart from my fault finding could be a bit better!!

just interested in your methods if say i had continuity on neutral and earth but not live??

just a case of checking all sockets for loose connection? what about no continuity at all? were would you start??

cheers fellas
any help appreciated

 

[ban-all-sheds]

FWIW, I'd probably start by connecting one leg, and finding which sockets still worked, then ditto with just the other leg.

And hope that I wasn't going to encounter a real-life example of why there is 526-04-01...

When all the pros get back from the pub you might get other ideas...

 

[Spark123]

Hic hic
I take it you talking about on a ring circuit?
You can start by connecting one of the circuit phase wires to earth in the CU as you would for an R1+R2 test on a radial, leave the other one disconnected and go around testing the resistance between live and earth at each socket.
Do the same for the other live wire. This should give you a rough idea of where the open circuit problem is.

 

[ian cotts]

I use the wandering lead method as I find it easier when checking continuity with the readings that I get back

 

[333rocky333]

If a new job then yes maybe loose connection.

As bas said connect one leg only, the martindale tester will show fault, at or after the bad connection.

If an old job,and the cable is suspect rather than a joint and all else fails ,may be best to remove all sockets if possible , continuity test between each core, and create a drawing of how its wired and go from there.

I found all 3 cores open once, found a floor box never fitted in an office,
carpeted over,and forgotten for over ten years.

 

[Spark123]

If a new job you should not get as far as powering it up

 

[333rocky333]

If a new job you should not get as far as powering it up

Agreed !

I assumed he meant fault finding on an install that had been previously energised and in use.

By new I actually meant recent,where it would be unlikely to be cable damage.

If it was brand new , it would be worrying if he had got to that stage without realising a socket was left off and THREE cores open circuit

 

[Spark123]

My opinion is that you are better fault finding on a dead circuit unless it is unreasonable. I cannot see why it would be unreasonable to fault find a socket circuit with it powered off, as you will have already turned it off to find the fault (lack of continuity) in the first place.

 

[333rocky333]

alright fellas,

in college still but i'm fine at everything apart from my fault finding could be a bit better!!

Reading this , yes agreed, ALWAYS better to work on disconnected circuits Especially faulty ones.
I was getting a bit confused ,maybe you mean , finding no continuity on initial testing BEFORE energising the circuit

I was thinking more on the lines of faultfinding where perhaps one or two sockets had failed on a premises, where it may be easier to see what sockets do work , then concentrate on the faulty section.

The only LIVE testing would be to do that, you would then ISOLATE

 

[Spark123]

How would you know there was a fault on the socket circuit if it were a ring? For one or two sockets on a ring to fail (owing to the foresaid type of fault) would you not need to have 2 breaks?

 

[daytona]

turn any spurs on,one by one.more common than you may think.even just on one conductor

power off though obviously,just close the switches

 

[Spark123]

You mean if someone has miswired a fused spur unit and wired one side of the ring to L in and the other to L out?

 

[daytona]

spot on mate.made hard work of saying it though didnt i?

been called in to do perodics on 60 trendy apartments in london.all new build.found it three times already,only done ten tests so far

 

[333rocky333]

How would you know there was a fault on the socket circuit if it were a ring? For one or two sockets on a ring to fail (owing to the foresaid type of fault) would you not need to have 2 breaks?

Depends on what level you noted the lack of continuity
Unfortunately there are circuits that are not continuous before a fault occurs or becomes apparent

One job I went to, two out of about ten sockets on the circuit not working.
32 a mcb , two wires marked up ring , all looked ok,turned out mice chewed wire last year , so someone disconned it and left it on two radials still from the 32a.
Was not till the other two sockets failed anyone noticed, mouse had chewed through another cable on the same circuit.
This building now has two 20 a radials,with the middle section disconnected and two non working sockets.

Other job went to mcb was tripping , disconnected and tested again all three open circuit, traced to two T+E cables cut off , still live, someone had forgot to fit the socket on the end.
So the so called ring was not a ring.

Another job half an office failed due to socket terminal burning out,with a ring , should not have lost more than one socket as you say ,turned out one socket was missing already and cables not joined.

This is the downside of the ring and the main reason for indepth testing as a majority of faults will not be apparent till the second fault occurs

I think the OP is more at the early stage, so this may not be relevant,but if he is faultfinding on his circuits , prior to there use, then he needs to brush up on his terminating skills , then he may not need the faultfinding skills so much

 

[kevnurse]

How would you know there was a fault on the socket circuit if it were a ring?

My understanding of the OP's scenario is that he has the two ring cables in his hand at the CU (not connected to the CU) and while there is continuity between the ends of the CPCs and the neutral wires, there is no continuity between the ends of the phase wires. IE there is a break in the ring, somewhere.