Broken Ring

[m4tty]

Hi,

Went to job today to add an FCU for new boiler being put in by plumber friend. Saw a socket with 2 cables feeding it so thought ring.

Done end to end tests and no continuity through Live, Neutral or Earth. This is being fed from a B32 in an MK board.

Had a look around trying to find the break but no joy so wondered whether it would be ok to change the 32A breaker to a 20A? With both legs in the same 20A breaker.

The house socket circuits are split between upstairs and downstairs so no kitchen circuit. If i downgrade the CPD to 20A do you recon they will have overload problems. Its a standard 3 bed Semi.

Any pointers and advice appreciated as I havent wired the fcu in or cert'd yet

Thanks in advance

Matt

 

[gselectrical]

Hi,Went to job today to add an FCU for new boiler being put in by plumber friend. Saw a socket with 2 cables feeding it so thought ring.

Done end to end tests and no continuity through Live, Neutral or Earth. This is being fed from a B32 in an MK board.

Had a look around trying to find the break but no joy so wondered whether it would be ok to change the 32A breaker to a 20A? With both legs in the same 20A breaker.

The house socket circuits are split between upstairs and downstairs so no kitchen circuit. If i downgrade the CPD to 20A do you recon they will have overload problems. Its a standard 3 bed Semi.

Any pointers and advice appreciated as I havent wired the fcu in or cert'd yet

Thanks in advance

Matt

If the kitchen is on a different circuit and they have either central heating or storage heaters (no plug in heaters everywhere!) then i dont think there will be overload issues.

GS

 

[Lee321]

nothing will be overloaded however nuisance tripping maybe an issue.

are they paying you to fix it?

 

[Evans Electric]

If its a radial using 2.5 you should derate the breaker , MK do a 25A which I used on a similar problem a few weeks ago . Whether they have problems is beside the point TBH , you will have left it safer than before .

 

[tom1]

will the length of the circut pose volt drop issues?

did you do your end to end at the cu?

and could you split it over 2 mcb?

 

[Tooold]

I was going to say do an end to end at cu if it aint a ring try two circuits 16 or 20 depending upon loading etc.

 

[m4tty]

If the kitchen is on a different circuit and they have either central heating or storage heaters (no plug in heaters everywhere!) then i dont think there will be overload issues. GS

Cheers for reply mate. There is only 2 socket circuits. Upstairs and downstairs so kitchen is on downstairs socket circuit.

---------- AUTO MERGE Post added at 17:56 ---------- Previous post was at 17:53 ----------

[quote name='Lee

 

[sparkytim]

You may find the socket you were testing at was a spur feeding another spur, so if you test at the C Unit and get Ring continuity it may be it is just this spur that is incorrectly wired.

Down grade to 20 Amp simplest solution but just warn Client MCB may trip if using more then 20 Amps.

 

[m4tty]

will the length of the circut pose volt drop issues?did you do your end to end at the cu?

and could you split it over 2 mcb?

The length of the circuit will not pose any volt drop issues mate. I done end to end at the socket i was planning to spur off and could split it over 2 mcbs but im not sure if there are interconnections between the 2 radials somewhere so thought if it was on one mcb then it would be safer than 2 incase there are any shared neutrals between the 2 radials.

Have i done this the safest way? I been thinking about it constantly and want to make sure ive done it correctly. So any critisisms/advice/help appreciated

Thanks

Matt

 

[Lee321]

just as sparky said matty. when you down grade to 20a that is the device that prevents overloads i.e they cannot happen. but by doing so you increase the likely hood of nuisance tripping because items plugged into the 20a circuit may go over the 20 and pop it out

 

[tom1]

You may find the socket you were testing at was a spur feeding another spur, so if you test at the C Unit and get Ring continuity it may be it is just this spur that is incorrectly wired.Down grade to 20 Amp simplest solution but just warn Client MCB may trip if using more then 20 Amps.

The length of the circuit will not pose any volt drop issues mate. I done end to end at the socket i was planning to spur off and could split it over 2 mcbs but im not sure if there are interconnections between the 2 radials somewhere so thought if it was on one mcb then it would be safer than 2 incase there are any shared neutrals between the 2 radials.Have i done this the safest way? I been thinking about it constantly and want to make sure ive done it correctly. So any critisisms/advice/help appreciated

Thanks

Matt

see sparky tim post

 

[maccarooni]

with ref to the 25A mcb to fit an MK board, If you have a CEF local to you, they do a range of mcb's at my local branch called MCG and these come in 25A. Have used many of these mcbs and not had any problems. If fitting on a standard mk busbar you just need to trim 5mm off the said connection point on busbar. HTH

Macca

 

[ADS]

Hi Matt,

Have you tested the ring final (end to end) at the board yet?

As Tim suggested, this sounds more like a spur than a broken ring.

Sounds a bit strange for no continuity on all three conductors

This would be my first port of call, otherwise you may be downgrading a perfectly good ring final to 20/25 A

 

[initforthemoney]

Schoolboy error.

Never assume.

Just because there are two cable behind a socket dont mean its a ring.

You should have checked at the cu and tested there.

If its still OR then it could even be 2 radials from one MCB.

 

[M107]

http://www.edwardes.co.uk/externalIndex.jsp?skid=MKE5925S

 

[m4tty]

Schoolboy error.Never assume.

Just because there are two cable behind a socket dont mean its a ring.

You should have checked at the cu and tested there.

If its still OR then it could even be 2 radials from one MCB.

Yup, your right a schoolboy error headbang and not one ill be making again. Thanks for all the replies. Im back there monday so will update the outcome.

On a MWC are you allowed to insulation resistance test L&N to E or are L-N, L-E & N-E compulsary?

Thanks

 

[SPECIAL LOCATION]

Yup, your right a schoolboy error headbang and not one ill be making again. Thanks for all the replies. Im back there monday so will update the outcome.On a MWC are you allowed to insulation resistance test L&N to E or are L-N, L-E & N-E compulsary?Thanks

Nothing is compulsory...

BS7671 is NON STATUTORY...

(classic C&G question, which of these documents is Statutory/non-statutory)!



---------- AUTO MERGE Post added at 23:52 ---------- Previous post was at 23:47 ----------

Schoolboy error.Never assume.

Just because there are two cable behind a socket dont mean its a ring.

You should have checked at the cu and tested there.

If its still OR then it could even be 2 radials from one MCB.

Got to be perfectly blunt and honest here..

I dont always agree with some of Init's comments... :_|

But this one is Bang On the Money in my book!

:Salute :Applaud

Concurrences with "Initforthefunofitandthetoplessdancinggirls"

opcorn

 

[muffin]

an easy way to find breaks in the ring is to disconect one leg and liven up the other.

go around with a martin dale and find the last live socket.

then repeat the process for the other leg.

this should then show where the break is between two sockets.

this also works for just one conductor e.g earth or neutral.

but obviously make sure all appliances are disconnected while you do it and no one is using anything.

why not put it on two seperate radials, providing there is room at the db.

hth

 

[Theorysparky]

a big +1 on that

 

[ianmacd]

Hmm live testing. Would be better to use a wander lead. Accomplishes the same thing but much safer and complies more with HSE.