TT systems

[dayrider3883]

I have a neutral to earth fault that trips my main switch RCD disconnected neutral to bathroom lights and trip is ok is neatral to earth a problem on TT systems

 

[Amp David]

Its usually a problem on any system mate. Think how the RCD works and why it operates

 

[1shortcircuit]

Neutral to earth will create any RCD an issue as this is where it is doing it's job:thumbsup

 

[dayrider3883]

yes but i have the live circuit beaker switched off to the bathroom

 

[1shortcircuit]

yes but i have the live circuit beaker switched off to the bathroom

Is this related to the bathroom fan?

 

[dayrider3883]

no i have the fan disconnected with the bathroom circuit breakes off the main switch operates until i disconnect the bathroom neutral at the cu

 

[1shortcircuit]

no i have the fan disconnected with the bathroom circuit breakes off the main switch operates until i disconnect the bathroom neutral at the cu

Was this fault present before you started the work?

 

[malcolmsanford]

But I assume you have other circuits still live and switched on ...................think neutrals and think commoned up at the board ..........and now think why the RCD is still tripping

 

[dayrider3883]

No Lightings been ion abuot 1 year 4 spot lights

 

[dayrider3883]

Yes but with live off on lighting circuit i cant see how its nuetral can effect the other circuits

 

[malcolmsanford]

Line and neutral in a single phase installation ................................if you have a load (amps) going down the line they return on the neutral ......ok

You have a Ring final circuit with a load on it ..........so we flow down the Line and back through the neutral ....................still ok

You have a faulty light circuit which is tripping the RCD ..................isolating the breaker still trips the RCD, but when you disconnect the neutral it says in .................... still there

Now because your neutrals are commended at the board your getting the returns from your other circuits back to the neutral bar ...........remember the RFC. well when you connect your neutral from that light circuit into that bar .........you back feeding from the neutral bar into that light circuit, where there is a fault and causing the inbalance, that is causing the RCD to trip ......

 

[StuSpiers]

Draw an RCD out.

then think how the circuits are connected.

Your RCD sounds like it is working perfectly.

You have A neutral to earth fault on your bathroom circuit, switching the mcb off does not isolate the bathroom neutral.

Neutral current from other circuits is flowing up the bathroom neutral towards the fault therefore causing an imbalance of phase - neutral currents.

 

[dayrider3883]

but with the switch off to bathroom what is supplying the in balance

 

[StuSpiers]

your other circuits.

 

[1shortcircuit]

I think this thread may be stepping on the toes of "Questionable Competence" so I am out as they say in the Den.

Good Luck, I hope you resolve the issue:thumbsup

 

[trev]

Malcolm tells you in post 11 mate. Your lines go into the top end of your MCB, your neutrals go in the neutral bar. Turn off the MCB and line is isolated, the neutral is not as it is connected to all the other neutrals in the installation. Current flows from line through appliance then back down neutral. Obviously some of this is flowing down the neutral where the problem exists thus tripping the RCD.

 

[trev]

Was this fault present before you started the work?

No Lightings been ion abuot 1 year 4 spot lights

In that case you need to rethink what you have done, probably undo it and start again.
Are you aware that this may be notifiable work if you are not a member of a competent person's scheme

 

[Amp David]

Why do people insist on messing about in consumer units trying to fix things when they don't know what they're doing?

 

[trev]

Why do people insist on messing about in consumer units trying to fix things when they don't know what they're doing?

It's only a few wires mate, what can possibly go wrong?
Apart from a horrible fiery/painful death

 

[Amp David]

The things that I find interesting is that with a tiny bit of testing/fault finding, you'd have the answer in not a very long time. Since it appears the OP has actually completed the 2391, then I am now beginning to worry a little.