My electrician has confused me about how to wire a light switch - please can someone have a go at explaining what he's saying?

[PotatoSoup]

Thank you for this!

So, nearly all the light switches (all white plastic, no metal) that I've connected myself have all been one-gang switches with one length of t&e 1.5 cable going to them via a plastic dry lining pattress box from the light fitting. Line/brown wire to COM, blue switched live with brown tape to L1 and then the earth sleeved with green and yellow sheathing, terminated in the box using an In-Line Push-In wire connector.

My electrician came over to connect three complicated (for me) switches.

The first switch was downstairs: a 2-gang switch with one gang (if that's the right way to say it?) turning on/off the downstairs hall light, whilst the other gang on this switch turned on/off three lights, which were daisy chained together around the upstairs hallway.

The second switch is upstairs; a two-gang switch with the first gang controlling the same set of three daisy-chained lights and the other gang turning the bathroom light on/off.

The final switch again controls the three daisy-chained lights and the second gang controls the light in my little boys room.

When my electrician got here, I'd temporarily connected 2 switches:

a 2-gang switch with one gang controlling the bathroom light and one gang controlling one of the hall lights in my usual way, basically treating the switch as if it were two separate light switches, if that makes sense? So terminating the two earths in separate push-In connectors. (This was just while we waited for the electrician come to us - I knew he'd be changing the light switches to "pole" something or others).

With the second temporary switch, I did the same thing using a 2-gang switch to control one hall light and my little boys light.

Where my electrician threw me was when he said that instead of using the Push-In connectors, I should be using wagos and connecting all the earths together to form a continuous earth.

I should have questioned him at the time but I was in the middle of something else and couldn't break away to pick his brains, unfortunately. So now I'm just confused.

With a 2-gang switch this is doable because you have two cables coming in but you obviously only have one cable usually going into a 1-gang, one-way switch. So does this rule only apply with 2-gang switches? With 1-gang switches -with one t&e cable going into them in combination with plastic pattress boxes with no earth terminal connection - how would I connect the earth to another earth in this situation to keep the earth connection continuous? Or do I not need to? I'm baffled!! Please can someone explain what's what to me?

 

[pete01]

If you have two earths put them together in a wago or connector block.

If you have one earth obviously it has to go on it's own in a wago or connector block.

 

[pete01]

But why isn't your electrician connecting everything?

 

[pete01]

Or they should connect to the back box if that's metal.

Sorry it's late...

 

[PotatoSoup]

Thank you - that answers my question in terms of the practical side of things and I'll stop worrying

But I'm now just curious, how is the earth kept continuous with the one-gangs?

He's pretty much doing everything but we're renovating so switches are coming on and off walls so I can plaster etc.

 

[PotatoSoup]

Or they should connect to the back box if that's metal.

Sorry it's late...

No worries, I really appreciate you coming back to me this late at night!! My brain always locks on to these sorts of questions right before I should be sleeping - maybe I should be researching that problem instead of the Mystery of The Continuous Earth!!

 

[pete01]

The one gang switch wires will be going up to the feed in and out at the light, so there will be 3 earths at the light if that makes sense to you.

But I must say most people these days do it the other way around, feed in and out the switch so you end up with one twin and earth at the light.

 

[PotatoSoup]

So with a one-gang, the continuity is maintained through the light fitting... But then how come that's not the case with a 2-gang switch?

 

[pete01]

It is the case, 2 gang is just 2x1 gangs in the same switch, if you didn't join them together it wouldn't matter, but you've got to put them somewhere might aswell be together.

I'm assuming feed in and out of light, if feed in and out of switch then the earth's definitely need to go together.

 

[PotatoSoup]

Yeah, the electrician has wired the downstairs hall light like that - I'm presuming it makes for smaller bore holes, less cable throughout the circuit and fewer wires into the light fitting? All the DIY videos and articles on light switch wiring seem to just show the other way to wire lights up, unfortunately. I'll have to pull it down to have a look at what he's done. Do you end up with the light being "dead" if the light is turned off then- as in no electricity running to it at all?

 

[PotatoSoup]

It is the case, 2 gang is just 2x1 gangs in the same switch, if you didn't join them together it wouldn't matter, but you've got to put them somewhere might aswell be together.

I'm assuming feed in and out of light, if feed in and out of switch then the earth's definitely need to go together.

So it's more just a "might as well" put them together rather than it'll break the continuity?

I think I've sussed it - I wonder if there was some confusion because the electrician had to colleagues working with him, one of whom was doing the daisy-chain and he's also the chap who did the downstairs hall light running the continuity through the switches rather than the fittings. So I wonder if that chap had wired the daisy chain lights so that the continuity would be maintained through the light switches, not the lights, but the switch wasn't yet wired to account for that, so that's why the electrician said about the continuity needing to be maintained?

 

[Adam_151]

Even if both switch drops have earth continuity back to the main earth terminal then its still normal/good practice to connect them together at the switch, because

A) There is simply no good reason not to
B) Sometimes the connection at the switch is the only way continuity to a section of cable, e.g. a 3&e to a 2way wired conversion method, or where the circuit is looped via the switch. Its not sensible to start thinking "This one has got continuity through another path, so I'll keep this one separate but I need to join all the rest" It acheives nothing and invites errors
C) Extra parallel paths will slightly lower earth loop impedance and touch voltage as well as be redudancy incase you get an open cirucit earth elsewhere, all of which can be regarded as good things.

There are some situations where earths may be kept separate, but none of them are the slightest bit relevant to a domestic lighting circuit, things like a TT installation supplied from a TNCS one, single core Alu armoured tx unloading tails where circulating currents can be an issue, clean earth installations where protective earth to the installation and equipment grounds are kept separate, Intriniscally safe systems with separate power and I.S earths, and I dare say there are a few others but with the exception of the first one, they won't be seen in a domestic installation and a even a lot of electricians will never come across some of of them.

TLDR: You are over thinking it, you join all earths you have at a domestic light switch together, obviously if you only have 1, there is nothing else to join it to.

 

[ebee]

If the switch needs an earth connection (metal faceplate or metal back box) then in times gone by using singles for conductors you might often have just one earthwire so that was all that was needed but with using Twin and Earth cables or Three core and Earth cables we have more earths than we might need so we connect them all together. This is no bad thing because it lowers the resistance (impedance) and provides for some redundancy in case of a lost connection. It also sometimes has the benefit of ensuring that two circuits have their earthing terminals joined therefore again redundancy and reduces any risk of losing all earth continuity on one whole circuit by loose connection.

I once heard about a fellow who bought some T&E for wall lights, they were made of wood and contained plastic lampholders therefore "earth not needed because it`s of no use".
Well OK.
However apparently as he cut all of the cable lengths held his pliers on the earthwires and pulled the full lengths right out of the sheathing .

The mind boggles!

 

[JohnW2]

...However apparently as he cut all of the cable lengths held his pliers on the earthwires and pulled the full lengths right out of the sheathing .... The mind boggles!

Good luck to him

I have, on occasions, had good reason for wanting to do that (to get a length of bare copper wire!) but, unless it's a very short length of cable,my experience is that it's usually essentially impossible - even if one i strong enough (and the pliers don't slip (wind the conductor around its jaw a few times!), the conductor will usually tear apart before one manages to pull it out - so I've usually ended up having to slit the sheath (no good if the cable is to be 'used'!) . Well, that's my experience, anyway!

 

[ebee]

I wondered why pull it out in the first place and if he got a little bend/hook like shape when cutting it ruin the other two conductor`s insulation, seemed like a mad thing to do, apparently it was then pointed out to him that if the fittings where then changed to metal that he would need to add an earthwire back in somehow. Some folk!

Mind you, just as daft, some years ago a joiner was doing a job on someones house in the evenings in his own time. He left a list at the loca; woodyard and the customer picked it up and paid for it. He told me that every so often he would turn up and some items missing, the customer had a habit of returning stuff he thought was not needed then had to return to re-purchase it.
Besides anything else it made the job more expensive due to additional labour and customer was not pleased at being "overcharged". LOL.
I had one similar on a rewire "Where is that box of Earth Clamps?" customer had thrown it away because as I had not used them she thought I did not need them (I ran out of time to put use them that day so left them for the following day).