Two way trip

[Nicktric]

Hi, recently done a Cu change and tests were all fine, put up lights on one RCD down on the other rcd switched on fine. Switched on the two way in the hall and tripped. I thought I had mixed the neutrals as it's wired in singles but checked and all fine. If I move both circuits to one rcd and same neutral bar as previous board then no probs.
I am sure this must be quite common fault from 16th board to 17th but haven't come across it and can't see quickly where the fault lies but presume it is a neutral missing to one of the lamps if the neutrals have split at the board? Any ideas?
Cheers

 

[Nicktric]

Great idea and will work for landing light and quite easy as in the loft but for the two way ground floor light I would need to run a neutral to the rose either from upstairs lighting or from th board which is back to disruption.

 

[Des 56]

You need to have 2 seperated circuits for downstairs an upstairs under the 17th

?


Does your landing light have a cfl lamp fitted

 

[Nicktric]

Yes Des, why?

 

[Des 56]

There is sometimes issue with 2-way circuits that use a pair of strappers and a cfl with regular discharge of a build up of current in the cfl capacitor which makes them flicker
It doesn't occur with 3-core 2-ways

Try fitting a standard tungsten lamp to see if the problem dis appears
If so,there is a small cheap solution that can be fitted to the lamp holder to get rid of the problem

 

[Nicktric]

I could run a separate neutral from DB to the landing light on ground lights neutral bar as landing is powered from two way GF switch(thanks Richard) and then the live from same T&E could supply the hall light two way top switch and be connected to GF MCB if that makes sense? How's this sit with BS7671?

Cheers.

 

[NMc]

Hi Nicktric

Your solution of running a separate neutral from DB to landing roses will resolve the issue of a borrowed neutral and bring the circuit back in compliance with BS7671. Dont forget to remove the existing borrowed neutral between the landing and first floor circuit

This is how it should have been in the first place

 

[telectrix]

agree with NMc. ground floor neutral from a groung floor light or from CU. remove 1st floor neutral from landing light ( wago the 2 N's if it's not last in circuit,) label CU "landing light is on ground floor lighting circui"

 

[Nicktric]

Great thanks and how about the supply from upstairs lights supplying two way hall light at top switch? Just run a new supply to top two way switch back to DB and ground floor MCB? Thanks for tip about labelling CU.

 

[NMc]

Dont understand

From what I have picked up is your 2way picks up the feed from the hall switch on downstairs lighting circuit. Strappers to landing switch then feed from switch to landing light. The neutral is then from the landing light to upstairs lighting circuit. Standard borrowing of neutral on 2 way switching. The upstairs circuit has its own live and neutral

Simple solutions to this as previous

Is this not the case

 

[PSES]

Is there anyway you can get a length of 3 core and earth in there?

Like mark80 has said you need some strappers between the two. Do you reacon you could surface it mount it? Failing that then I would put both on seperate MCB's but on the same side of the RCD board and then put a note on the cert

 

[Nicktric]

Dont understand

From what I have picked up is your 2way picks up the feed from the hall switch on downstairs lighting circuit. Strappers to landing switch then feed from switch to landing light. The neutral is then from the landing light to upstairs lighting circuit. Standard borrowing of neutral on 2 way switching. The upstairs circuit has its own live and neutral

Simple solutions to this as previous

Is this not the case

Yes NMc it is ,also

There are two two ways one in the hall to switch on landing which needs a new neutral in the landing rose to match up with GF supply as discussed. Plus one two way switch on the landing to switch on hall light which has a supply from upstairs and a neutral in the hall rose from downstairs so was suggesting the t&e new run for neutral in the top rose from the GF neutral bar could supply the landing switch from the GF MCB? Wasn't sure if this was common practise if it's not feasible to use three core strappers.
Cheers

 

[Nicktric]

Like mark80 has said you need some strappers between the two.

Thanks PSES
Ideally yes but I think it will be easier and comply by running a new neutral from opposite rcd (GF neutral) for landing light. Then for the other two way hall light running a new supply to top switch from opposite(GF MCB) to suit GF Neutrals. Has anyone got any concerns with this?
Thanks.

 

[NMc]

You say this is wired in single so if you think about it all you should need to do is replace the borrowed neutral

The hall 2 way should be picking up its feed the same as the landing light at the hall switch. Strappers for both lights between hall and landing then single switch wires from second 2way to each light. The neutral for the down stairs light circuit including the hall should loop around all lights

Common practice many years ago was to borrowed the neutral for the landing. It made it easy for electricians. The hall always had the neutral from the downstair lighting circuit

 

[Ponty Massive]

Failing that then I would put both on seperate MCB's but on the same side of the RCD board

Don't do that. If you isolate the MCB to work on that circuit you could still have current flowing through the neutral. Best way is just put both upstairs and down stairs lighting on one MCB and make a note of that on the certificate.

 

[NMc]

Think you are missing my point Ponty Massive. I was highlighting this bad practrice

The easiest way to solve the matter is how you point out put both circuits on one MCB but that brings its own problems

To correct this properly you need to ensure the borrowed neutral is removed and there is no cross connections