Neutral and Earth continuity.

[andysdiy77]

Hello All,

I have found that i have continuity between the earth and neutral wires on my downstairs ring main.... Is this safe? Should i get someone in to look at it? I'm thinking it shouldn't be like this in case of a live to earth fault.....???

Any ideas?

Thanks,

Andy.

P.S. it's in a victrian house with old red/black T+E, probabley retro-fitted many many years ago....

 

[mikhailfaradayski]

are the wires still connected at the consumer unit when you check for continuity?

 

[andysdiy77]

Yes, still connected to the CU, I have just split the ring to put new sockets on and thought i would just check the wires as i don't have a CU with RCD's in. Interesting this is that there is only continuity between N and E on one side of the ring...?????

 

[1john]

did you disconnect all the live (line) and neutral conductors or just pull the fuse / switch off the MCB??

 

[andysdiy77]

I have just pulled the fuse for the ring circuit.

 

[1john]

have you got continuity beteen line conductors

have you got continuity beteen neutral conductors

have you got continuity beteen CPC conductors

the reason i ask is that if it is a 'ring final circuit' and you have split it at one place you should be getting the continuity from neutral to earth on both cables.

the reason you are getting continuity is because you are reading back to the star point of the generator / transformer.

 

[andysdiy77]

Thanks for the info, so what i am seeing there is ok then. For some bizarre reason i did not check the continuity of connections around the main, will look at that tonight.

The reason for posting is that the ring main now works ok by splitting as a spur in each direction but pops the fuse when connected as a ring....???? I just assumed i had some kind of earth leakage from the N and E contenuity. Have you come across this before? Thanks. Andy.

 

[ColJack]

you likely have PME supply.

ok, PME supply basics.. ( also called TN-C-S )

your neutral and earth are the same wire into your house, where it is split into live and neutral..

if the neutral is still connected in the CU then it SHOULD read as connected to earth..

//www.diynot.com/wiki/electrics:earthing-arrangements

 

[mikhailfaradayski]

Thanks for the info, so what i am seeing there is ok then.

possibly, but you need more information to be sure.
Is it a ring?
What size fuse is protecting the circuit?

For some bizarre reason i did not check the continuity of connections around the main, will look at that tonight.

The reason for posting is that the ring main now works ok by splitting as a spur in each direction but pops the fuse when connected as a ring....???? I just assumed i had some kind of earth leakage from the N and E contenuity. Have you come across this before? Thanks. Andy.

erm, what do you mean :-
you've got two cables, when seperated they work, when together causes fuse to go?

Doesn't sound safe so far.....

 

[Paul_C]

you likely have PME supply.

You'll still read continuity between N & E with TN-S or TT if the main switch is on, since the neutral is still earthed at the supply.