Hall/Landing lights - convention.

[dennis]

It should result in lots of interruptions in supply as the RCD part trips (although bad joints, etc. might actually prevent this).

Yes or the RCD.

[dennis]

Except for the error I just noticed.. the top live should be to the common.

[ARWadsworth]

You've lost me.

I cannot see an error.

Adam

[John Rumm]

>>> No borrowed neutrals (so RCBO safe), feed to each lamp from the adjacent

If there is a RCBO or RCD protecting one circuit that does not also protect the other, then the moment you turn one of the lights on that borrows the neutral, you will get a RCD trip on one or possibly both circuits since you will imbalance the flow and return on both circuits.

Yup.

[John Rumm]

So why did you previously say: "If its a two gang then the lives can come from any circuit, there isn't a rule that says otherwise."?

looks fine to me. Same arrangement top and bottom.

[Cicero]

>>>>> No borrowed neutrals (so RCBO safe), feed to each lamp from the >>> adjacent

================================================

Thanks - understood.

I've just ordered two RCBOs to install into the two lighting circuits. I'll get around to removing the borrowed neutral first sometime soon with luck.

Cic.

[dennis]

Having had another look I agree it works. Its not how I do them after all.

I wire live to common, then connect L1 to L1 and L2 to L2 using two of the cores and common back to the switched live using the third core. An intermediate just connects to the pair between the Ls.

Your way saves a joint BTW.

[Harry Bloomfield]

Cicero expressed precisely :

It means that every time the light with the borrowed neutral is turned on, that it will trip due to the imbalance.

That is the only solution to preventing the tripping, other than removal of the RCBO's.

[John Rumm]

That sounds like you would be "exporting" the local live to the other switch then. If so, how do you get the matching neutral there as well?

Yup, that's pretty much the same for most variants.

I don't claim invention of it, just what's in the OSG...

[dennis]

All the switches and cables are in the switched live bit so it uses the same live and neutral that would be in the rose on a normal switch drop.

[John Rumm]

perhaps I am having difficulty visualising it. Still never mind, it sounds like we are describing a subtle variation of the same thing.

[robgraham]

Yep - been there, borrowed a neutral many years before, and then couldn't understand why a particular light would trip the RCD in the new CU. Took several months of trying various things before memory kicked in ! It was all the more naughty in that the neutral had been borrowed from power circuit - logic at the time being that it was the nearest!!

Rob

[ARWadsworth]

I believe I have seen this before.

At the first lightswitch there is the perm live and switched live from the fitting. Perm live goes to common and the 3 core is connected to L1 and L2 of the switch with the 3rd core connected to the switched live with a piece of strip connector. At the second lightswitch L1 and L2 use the same two cores connected to L1 and L2 of the first lightswitch and the 3rd core goes to common.

You just need a piece of paper and a pen to visualise it

Adam

[John Rumm]

Ah, it was the bit of chocky block I had not spotted. Yup, can see it now. Can't see any particular advantage though, can you?

[chunkyoldcortina]

Which is why I don't want to mess with the electrics in our new house in the slightest!

All switches and sockets are very nice brushed steel finish (or chrome or whatever the design is called).

No problem with the sockets, but on any of the light switches (some are dimmers, some are regular switches) you can usually feel a very faint tingle, the same sort of tingle you get if you touch the metal case of a double insulated appliance (where the case is connected to 0v DC but not to the house earth).

Now part of me is wondering if this is because the 1960s/1970s house has two core twin cable feeding the lighting circuits (ie no earth) and some bright spark(y) in the past has decided it is a good idea to connect the faceplates to neutral as there's no earth, so that should there be ever be a fault where the faceplate could become live, it will blow the protecting fuse.

All it takes is for there to be a borrowed neutral and removing one or the other of the upstairs or downstairs lighting fuses could mean that the other switches become live!

[Dave Plowman (News)]

I'd get it sorted pronto. All the metal faced switches I've seen say they

*must* be earthed. If your wiring is so old it doesn't have an ECC, either replace that (best way) or change to plastic switches.

[ARWadsworth]

Yes, I would say this needs sorting.

I also doubt that there is a neutral behind the switches that could be connected to the face plate.

Adam

[Dave Plowman (News)]

And would any sparks actually do this anyway?

I have seen one pro installation where a signal light on a light switch used the earth as return - I'd guess they forgot to install the correct cable as it was on the spec - but not the other way round.

[ARWadsworth]

Hopefully not! I would explain the situation to the customer and try to start by installing plastic lightswitches. If the customer refused then I would walk away. Better to lose half a days income than be plastered all over the local paper when things go wrong.

No surprises there then. Apparently is was a pro electrician that wired up my brothers first house (a newbuild 20 years ago). For some reason the pro laid the 3 core strapper in a straight line between the landing light switch and hall wall lightswitch. The installation of a new handrail soon found that cable:-)

Some signal lightwitches do use a neon and are supposed to be OK using the earth as the return. I would not do that on a new install though.

Adam