Polarity puzzle

[Shay butler]

I recently came a cross a piece of 3core swa brown black grey, that had been attatched to a piece of 2 core red black swa. I have confirmed that the brown conductor is attached to the red conductor and is indeed the line conductor. How can i determine which core, either black or grey has been used as neutral? The swa has been connected using a sealed compound joint so i cant see the connection. I only have access to the db supplying the 2 core swa to turn the mcb on or off.Hope this is clear enough for somebody to help!

Thanks guys

 

[telectrix]

one way would be to connect it up with a RCD at the source . then when you plug in and switch on an appliance, if the RCD trips, N/E are reversed. ( defdinitely a don't try this at home ). the correct way would be to use a wander lead and " bell" the conductors.

 

[msec]

Am I correct in thinking you can you not check at the load end? How have you checked the line conductor?

 

[1shortcircuit]

one way would be to connect it up with a RCD at the source . then when you plug in and switch on an appliance, if the RCD trips, N/E are reversed. ( defdinitely a don't try this at home )

.

Is it Fun-time Friday again already lol

the correct way would be to use a wander lead and " bell" the conductors.

Yep, if you don't have one then you can make one. I keep a roll of single core for the occasions where I need a wander lead

:thumbsup

 

[Shay butler]

I can check at load end. I can't check at the supply end. I know browns line because voltage between brown an black an brown an grey is 230v but between black an grey voltage is 0v

 

[telectrix]

can you not access the supply end? short out the red/black at supply DB, then find out at the other end which colour has continuity with the red, then that is your neutral.

 

[vernam616]

Well in theory if it was me who had installed, id of used the Grey as neutral and sleeved the black with green/yellow

However not everyone conforms to normal sparky life and make their own colours/rules up

 

[vernam616]

Why cant you check at supply end? im presuming you know where the supply is, otherwise how will it be isolated? and how can you carry out the necessary testing/inspection?

 

[telectrix]

However not everyone conforms to normal sparky life and make their own colours/rules up

same as happened in 2006. then it was the bureaucrats and the IEE making up the colours.

 

[1shortcircuit]

Well in theory if it was me who had installed, id of used the Grey as neutral and sleeved the black with green/yellow

However not everyone conforms to normal sparky life and make their own colours/rules up

That is how I would do it also but I would have also sleeved the grey with blue to identify the neutral

 

[Silly Sausage]

I can check at load end. I can't check at the supply end. I know browns line because voltage between brown an black an brown an grey is 230v but between black an grey voltage is 0v

That implies (to me) that the black & grey are connected at the joint.
Buzz the black & grey to check.
Otherwise, connect a lamp, or something, brown/black and brown/grey and see which way lights it up.

 

[telectrix]

That implies (to me) that the black & grey are connected at the joint.
Buzz the black & grey to check.
Otherwise, connect a lamp, or something, brown/black and brown/grey and see which way lights it up.

the lamp will light up on L/N and also on L/E, unless the cable is RCD protected, then if it's across L/E the RCD wil not like it and go home, taking his toys with him.

 

[Silly Sausage]

the lamp will light up on L/N and also on L/E , unless the cable is RCD protected, then if it's across L/E the RCD wil not like it and go home, taking his toys with him.

See what you're saying there though, N/E connected through the supply. I'm assuming (ABTMOAFUa) that his 'spare' core isn't connected to earth at the joint, that it's either floating or connected to the other (Bl/Gy) at the sealed joint. If the spare core is earthed at the joint it makes it a bit more difficult! He needs to get that DB opened up!