Wiring an extra light to a 2-way switch via a relay

[at0mic]

I want to add an extra light to my hall but I dont have an attic so I cant get power from one of the other celing roses.

I tried wiring a light to the 2-way light switch to see if it would power the light. The light worked however, the light was on when the others were off. When I switched the other lights on, this new light went off. It did the oppisite to the others.

I came up with the idea of wiring a relay switch in reverse so that when I turned on the lights, the relay activated a separate which got its power from a separate source. This would allow me to switch all my hall lights on together.

Can anybody see any problems with my plan?

 

[RF Lighting]

Yes.

Your proposal will not work.

You need to get a neutral to your new light which will not be provided by the switch, relay or no relay.

You need to get a cable from the existing fitting to the new one.

 

[breezer]

see the wiki, thats what its for

 

[at0mic]

yeah but the light DID work because I tried it. It was just reverse.

 

[breezer]

your problenm is that you do not understand the principlas of what you are doing, there by realising your error, if you did you would not be asking the question

put it this way.

do you suppose that to add a light everyone uses a relay?

 

[at0mic]

no of course people don't use a relay in domestic lighting. If I had access to an attic, I would never dream of using a relay in a million years. Its a bit of a bodge job plus the relay wouldn't last much more than a year or two anyway. When the lights are off, power would be going to the relay constantly which will strain it and wear it out. Plus the noise of the relay's click will be heard when the switch is flicked.

The reason I asked was because its the only solution I can think of as I don't have access to the ceiling rose. I know I can get power from the switch because I managed to power a light as I explained. The reason I was asking is because I've never heard of a relay being used in domestic lighting so I wondered if there's any fire risks involved or any other implications.

 

[breezer]

it wont work how you think, that is the "problem"

 

[securespark]

The reason your light probably worked "in reverse" is because the "neutral" is not a true neutral, but one back-fed through the lamp when the light is OFF.

You will have to pick up a neutral from somewhere on the same circuit.

 

[RF Lighting]

no of course people dont use a relay in domestic lighting.

I Think you just answered your own question.

I know I can get power from the switch because I managed to power a light as I explained

And as I explained IT WILL NOT WORK.

You need a neutral.

There is no way around it.

You managed to make a lamp light up, but it is not wired properly.

You have effectively wired you 'test' light in series with another light which is not good.

 

[at0mic]

The reason your light probably worked "in reverse" is because the "neutral" is not a true neutral, but one back-fed through the lamp when the light is OFF.

You will have to pick up a neutral from somewhere on the same circuit.

I do have very easy access to the ceiling rose in the spare bedroom because I'm currently building a partion and putting up a false ceiling. Anyway, so your saying I could get my live from the Hall switch and my neutral from the bedroom? and this new light will be activated from the switch in the hall?

 

[RF Lighting]

Providing the bedroom light is on the SAME circiut as the hall switch then yes.

 

[breezer]

like i said, see the wiki

 

[Steve]

<visions of at0mic stripping a piece of T+E and feeding the single neutral up the wall>

 

[breezer]

dont say that, he will