Pneumatic time lag switches-replacing

[600rob]

Hi,


I would like some advice on replacing some pneumatic time switches.
The current set up is as follows:
There is one light at the bottom of the staircase/corridor and one light at the top of the staircase.

In the corridor at the bottom of the staircase there are two of these switches.
http://www.elkay.co.uk/product.asp?id=1&catid=1
At the top of the staircase is a single switch of the same type

The two switches at the bottom of the stair case are wired as follows:
Switch 1: located at the entrance to the hallway at the bottom of the stairs has 2 lives going to the com terminal and two switched lives going to the NO terminal. The circuit uses 2 core wiring so the NC terminal is left empty.

Switch 2 located at the bottom of the stair case is wired the same as switch 1

Switch 3 is located at the top of the stair case. This switch has a single live going to the COM terminal and a single switched live at the NO terminal. Again the NC terminal is left empty.

Any one of the three switches, when switched on will turn on both lights in the stairwell for the programmed time period

I would like to replace the 3 switches that are currently fitted with one of these:
http://www.tlc-direct.co.uk/Products/DNTLSW10ILM.html (master switch)
And two of these
http://www.tlc-direct.co.uk/Products/DNSS1SL.html (slave switches)

My question is will the current wiring arrangement dictate where I will be able to put the Master switch?

I would like to put the master switch at the top of the stairs in place of switch 3 as there are no windows to provide any natural light but im not sure if this will affect the operation of the two slave switches?

Would any one be able to advise on whether i can do this or not?

Thanks

 

[EFLImpudence]

Using only the present wiring (only 2 wires) and a master with two slaves you will have to have the master at the bottom.

Of, course you could use three masters.

 

[600rob]

Thanks for confirming that. Will probably get a couple of non illuminated masters to go at the bottom of the stair case then.

 

[JohnW2]

Thanks for confirming that. Will probably get a couple of non illuminated masters to go at the bottom of the stair case then.

Despite what EFLI suggested, and assuming that I'm not missing something, I'm not convinced, on the basis of the documentation, that you could have two (or more) of those Danlers masters connected. You could have one master and as many slaves (just simple push button switches) as you liked, but I'm not at all sure about more than one master - it might be worth asking.

Kind Regards, John

 

[EFLImpudence]

Why not? What does it say?

 

[JohnW2]

Why not? What does it say?

Are you perhaps talking about using two masters in parallel, without interconnecting them, and then running a slave off one of them? If so, that might work, but since these no-neutral electronic devices will be deriving power for the electronics via the load (as 'neutral') I'm not sure what would happen if you wired two of them in parallel - since the S/L would go up to approximately L potential when one of them 'switched on', potentially frustrating the electronics of the other one. Maybe its not a problem - I just don't know.

Kind Regards, John

 

[EFLImpudence]

Three (or any number) in parallel.

There is a diagram on page 49 of the manual.
(sometimes I can't paste on here)

It definitely works with other master switches.
I don't know why these would be any different.
It doesn't matter about 'frustrating' the electronics in the other switches as the pushed one will have switched on the light.
The illumination will go out when both sides are at 240V but that doesn't matter because the light is on.

 

[EFLImpudence]

www.danlers.co.uk/images/downloads/catalogue/Time lag switches.pdf

 

[JohnW2]

Three (or any number) in parallel. ... There is a diagram on page 49 of the manual. ... It definitely works with other master switches.

Fair enough - there's no problem, then (I hadn't seen that diagram before, only the one, with just a single master, in the installation guide).

It doesn't matter about 'frustrating' the electronics in the other switches as the pushed one will have switched on the light. The illumination will go out when both sides are at 240V but that doesn't matter because the light is on.

I didn't go into detail as to what I meant by 'frustrating the electronics' but, since you raise the issue, I'll explain what I was thinking ... I think that some of these sort of electronic switches (like many PIRs) go into a 'triggered' mode (for their timed period) at power-up. With two 2-wire devices in parallel, if the light was switched on by one of them, the other one would essentially see a 'no-power' situation (as you say, the illumination will go out).

When the light goes out, power (p.d. between its two wires) to the other switch will be restored. IF it were a device which powered-up into its 'triggered' state, the light would then come back on for the timed period, and one would have started a continuous cycle - each time the light went out the other device would power up and start a new on-cycle. However, given the above, I presume this does not happen with the switches we are talking about.

Kind Regards, John