2 way lighting help please?

[DPrice]

Im currently coming to the end of my 1st year at college (C&G 2330 Level 2). So my knowledge is some what basic/getting there.

I am reasonably confident at basic wiring and fault finding so i do now and again lend a helping hand to family.

So heres the problem - My grandad was decorating the other day and to do a proper job took off all light switches and sockets in the living room/hallway/staircase.

He then rang me a few days later and asked if id mind going over and refitting some new sockets/switches which i happily did.

However there is 1 problem - At the bottom of the stairs (in the hallway), there is a 2 gang 2 way switch, 1 side operating the hallway spotlighting, the other operating the light at the top of the stairs (which is also connected to a 1 way switch at the top of the stairs).

BUT there is only 1L and 1N from upstairs, and 1L and 1N from hallway?

And in the back of the switch i have 2 Commons, L1 L2 and another L1 L2.

Is there a way i can get both lights working simultaneously off this switch, whilst still being able to operate the upstairs light with the switch upstairs without 3 core cable? (for instance being able to have the hallway lighting on, whilst being able to turn the stairs light on at the bottom, and off when get to the top?)

If not, (which i think i'm right in saying i cant without 3 core) is there a way to make the hallway lighting permanently live and only have a single switch there for the stairs? (as the spotlights also have push button which could be used instead)

I hope this isn't too confusing.

Any help appreciated

 

[chris gray]

learn from this mistake mate, always mark your cables when disconnecting.
im assuming that there is a link wire in the back of your 2g sw?
work on one side first: the downstairs which isnt 2way'd
connect a l in with the linkwire (make sure you tighten the loose end. and the n into the l1
tell me what happens....
hopefully the downstairs should work, if not take them 2 wires out and do it with the other 2 wires.
if that works...
#put the l into l1 and the n into l2 on the other side of the 2g sw

 

[Notsosmart]

To help you out dan see diagram below;

 

[DPrice]

Thanks for the replies chris_gray and Notsosmart really appreciated.

In answer to your post chris - No there isn't a link wire in the back of the switch? (would this be joining both commons)

There's just common, L1, L2 on one side,

and for other switch common, L1, L2.

 

[JUD]

Are you saying that you have 2 T&E's coming into the switch instead of 1 T&E and 1 3 core?

Did the lights work before?

 

[rocker]

Had a bit of a think about this - is there a CPC in the cable for the landing light? Willing to put money on it that the CPC has been used as the common strapper to save a few pennies by whoever put it in (probably when CPCs weren't required in lighting circuits.) Check if the CPC looks like it's been terminated, and ask your grandad if he took cables out of the earth terminal (if it even exists in the backbox)

 

[DPrice]

No, there are only 2 cables coming in to the switch.

1 live and 1 neutral from landing
and
1 live and 1 neutral from hallway

No CPC or SW

With regards the lights working before I recall the hallway lighting being used on the push button.

Which made me think could I wire the landing lights on the switch, and the hallway as permanent and just use the push button on/off on the unit itself.

I hope this makes sense, thanks everyone!

 

[rocker]

What is in the back of the upstairs switch and the push button?

 

[JUD]

First thing you need to do is find out which cable is for the hallway lights (if you haven't already).

On one of the cables join the live and neutral wires together and test for continuity between live/sw. live and neutral at hallway light. If you don't get a reading try same thing on other cable.

As the hallway is only 1way the neutral wire will likely be your switch wire and should be identified with brown sleeve. You can connect that to one of the gangs in the switch. Brown to Common, Blue (with brown marker) to L1.

If the other cable is also T&E, I would think that it is probably wired as Notsosmart's diagram suggests probably using the live and neutral wires as strappers and the light getting it's neutral from elsewhere. Take a look at how the upstairs switch is wired. If you have brown and blue wires going to L1 and L2 then I would say this is the case. If so, in the downstairs switch you will need a link from the common of the hallway switch to the common of the landing switch, then brown and blue(marked brown again) into L1 and L2 of landing switch.

Something like this:

 

[rocker]

Of course!

 

[baldsparkies]

If in doubt, bell em out. find out which is the live feed, which is the switch returns and which is the strappers. Check this out on the landing as well as the hallway switching. Once you know what is what you can figure the right combination to get it up and running again. My guess is you have a switchwire from the hallway light with the live linked to provide a feed to the landing light, along with a twin cable being used as a strapper and a single from the landing 2 way going up to the landing light fitting.

Just seen Juds diagram, thats the boy. Just swap the blue for black and brown for red and your good to go.

 

[rocker]

JUD man, post that in the new 'problem solved' sticky at the top of the forum. If you don't, I will (and give you credit of course!)

 

[JUD]

What do I do just copy and paste it in that thread??

**EDIT** Doesn't matter. Done it

 

[rocker]

Don't ask me, I'm the ideas guy not the details guy!

 

[JUD]

I hope I'm right!!!

 

[rocker]

I hope I'm right!!!

That's a good point.....

 

[JUD]

I hope I'm right!!!

That's a good point.....

Was only a suggestion (if I'm wrong)

If I'm right........COME ON!!!!

 

[DPrice]

Thanks everyone for your replies, really appreciate it!

Im going over this evening so ill have a look and let you know the outcome.

 

[DPrice]

So just been over and wired it up this way.

All's working fine. The stairs light is on the switch, and the hallway lights permanently live (using the push buttons on the unit to power on/off)

Again thanks everyone for your help, really appreciate it..

 

[JUD]

If the hallway lights are permenantly live, what is the other switch for??

Something doesn't add up

Who fitted the lights? I reckon they've been wired to the loop instead of the switch live.

 

[DPrice]

Yes the hallway lights are permanently live now.

The stairs lights are switched.

The lights were in the house when they moved in 15 years ago. It's just my grandad has redecorated but this time took all sockets/switches/fittings off to do a proper job.

With regards to the way it worked before I couldn't tell you as it wasn't me who took the old switch off.

As suggested earlier i've linked both commons, and put the L from hallway in with the common and the N in L1
and
L and N for stairs lighting in opposite L1 and L2!

In the back of the switch upstairs there is both L and N in L1 and L2.

 

[chris gray]

dude thats why its permenantly fed then, you're switching a perm feed across both l1 + l2 on your downstairs light.
anyway glad you sorted it.

 

[JUD]

dude thats why its permenantly fed then, you're switching a perm feed across both l1 + l2 on your downstairs light.
anyway glad you sorted it.

First thing you need to do is find out which cable is for the hallway lights (if you haven't already).

On one of the cables join the live and neutral wires together and test for continuity between live/sw. live and neutral at hallway light. If you don't get a reading try same thing on other cable.

As the hallway is only 1way the neutral wire will likely be your switch wire and should be identified with brown sleeve. You can connect that to one of the gangs in the switch. Brown to Common, Blue (with brown marker) to L1.

If the other cable is also T&E, I would think that it is probably wired as Notsosmart's diagram suggests probably using the live and neutral wires as strappers and the light getting it's neutral from elsewhere. Take a look at how the upstairs switch is wired. If you have brown and blue wires going to L1 and L2 then I would say this is the case. If so, in the downstairs switch you will need a link from the common of the hallway switch to the common of the landing switch, then brown and blue(marked brown again) into L1 and L2 of landing switch.

Something like this:

Chris. I think it's been wired as per the above diagram as he has a 1 way light at the bottom of the stairs and a 2 way light at the top of the stairs but he only has 2 T&E cables coming into his 2 gang switch at the bottom of the stairs where you would normally expect to see a 3 core for the 2 way switching.

By the sounds of it, I was right about the 2 way but the switch that is supposed to be for the hallway light isn't doing much so that's why I think it's been wired to the loop live instead of the switch live at the light making it permanently live.

 

[bluesky]

if cpc used as a switch wire, it carries current, is this allowed nowadays?

had this problem, if i decide to replace the cpc with an insulated cable, do i have to open the floor to find cpc?

thought this is an easy job, if i have to open the floor, it is just a nightmare

 

[Sintra]

if cpc used as a switch wire, it carries current, is this allowed nowadays?

had this problem, if i decide to replace the cpc with an insulated cable, do i have to open the floor to find cpc?

thought this is an easy job, if i have to open the floor, it is just a nightmare

No not in my book.
Anyway if you use the cpc as a switchwire what do you use as the cpc?

 

[bluesky]

No not in my book.
Anyway if you use the cpc as a switchwire what do you use as the cpc?

this is bad, who invented this kind of wiring? just left hugh mess behind

 

[TPES]

Just one note on JUD excellent diagram. It shows the same neutral feeding both lights, which in an ideal world that's what we'd all want especially on a CU change. But it's quite often in older houses that the neutral is fed from an upstairs circuit for landing light and neutral from downstairs circuit for hallway light. But both fed with the same com. For a basic 2w switch your diagram is very easy to follow for someone learning.

 

[bluesky]

what is the best way to correct this 'borrowed neutral' problem?

 

[soulman]

hi can i just ask,
the diagram that jud has drawn is this how you get a borrowed neutral as the upstairs light could have neutral taking from upstairs circuit and power from the downstairs circuit. as i am a bit confused to what a borrowed nuetral is?
cheers

 

[TPES]

A borrowed neutral is just that, it will be a neutral borrowed from a different circuit, there are houses that only have one lighting circuit, some have 2 or more, you shouldn't be taking a neutral from a different circuit, it will trip your rcd for 1 thing

 

[JUD]

A borrowed neutral is usually found on 2 way lighting circuits at the top of stairs.

It basically means that the live feed is taken from the downstairs lighting circuit and the neutral from the upstairs circuit.

Because upstairs and downstairs lighting circuits are fed from different RCDs in a 17th Ed CU you end up with nuisance tripping due to excess neutral current in the upstairs lighting circuit.

 

[TPES]

A borrowed neutral is usually found on 2 way lighting circuits at the top of stairs.

It basically means that the live feed is taken from the downstairs lighting circuit and the neutral from the upstairs circuit.

Because upstairs and downstairs lighting circuits are fed from different RCDs in a 17th Ed CU you end up with nuisance tripping due to excess neutral current in the upstairs lighting circuit.

Well said!

I've had a few to write any sense