Cord operated intermediate switch

I would like to replace the intermediate switch in the lighting circuit in my attic study. At present it's an ordinary box mounted-on-the-wall unit inconveniently mounted out of reach. What I want is a cord operated pull switch mounted in the ceiling. I have never seen one of these in any wiring catalogues. Does anyone supply them?
If not has some enterprising soul worked out a circuit that will mimic the operation of an intermediate switch, perhaps with suitable relays, that can be controlled with an ordinary pull switch?
I used to work in a building where every fluorescent light unit was equipped with a pull switch on the lamp. At 12 pm and 7 pm all the lights were switch off centrally and a tug on the cord was required to switch each one back on. Quiet neat but not relevant here!
TIA
Richard
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Couldn't you just fit a pull cord switch to control the light only, instead of actually operating as a intermediate switching point.
The only other thing I can think of doing, is to re-configure the wiring to suit a two way pull cord switch.
Bit it might still be an idea to try your local Leccy wholesaler to see if some manufacturer has come up with the idea.
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together this:

Not that I've ever seen.

Relays, two SPCO with the coils wired in parallel switched from a 1 way pull switch. Assuming the strappers are yellow and blue then connect;
The two yellows to relay a and b com. The two blues to relay a and b NO. Relay a NO to relay b NC. Relay b NO to relay a NC .

That could be pricey! I'd forget that notion!
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Lurch wrote:

Ta Lurch,
Simple when I stop thinking about latching or changeover relays with mains coils and how to power them! I suppose however I could use a pair of SPDT latching relays if I could find a momentary pull switch, thus extending the life of any battery derived coil supply.
Richard
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together this:

Always best to stop thinking if you want to work something out!

Well, I think standard 230VAC relays would be the easiest to source, as would be a 1 way pull switch as opposed to a momentary one. I know that I could walk into my local CEF tomorrow and get all the bitsd I'd need to do the job.

I'd use mains relays and power them from the lighting circuit,for the sake of running a neutral in from the lighting circuit it's better than having batteries.
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strung

The only thing about using a relay, is that the solenoid coil in the relay would have to stay on in one position, when switched. If left for a long period, the coil may create enough heat to either the enamel on the coil and blow fuses, or to cause a fire in surrounding materials when the relay housing melts. I personally don't think a relay is the way to go, unless you can source one that is designed to be left energised for long, long periods of time.
The wiring could be configured to make the switch positions different. The now intermediate switch could be placed at one of the points where a two way switch is now. We already have four conductors at the intermediate position, so you could fit a two way to this point and use the remaining conductor a pass through to one of the other points and make it into a intermediate switch point.
We need to know how the light fitting is connected to the switching system. Things like, does the negative also enter at one of the switch points? Does the live feed to the light fitting come from the opposite end of the circuit from the supply?
Where does the light fitting pick up its negative? Are there any pass wires already coming through any switch points?
More input. :-)
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On Sun, 09 Jan 2005 22:19:28 GMT, "BigWallop"

That's something I did briefly think about. You could use one of those electronic relay alternative kits with no moving parts instead.
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SJW
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strung together this:

would
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Now that's a better idea. A bit more money, but actual working needs would suit them. I never thought of one of those. Web search mode engaged. :-)
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strung together this:

Covert all the switches to momentry and use an impulse relay
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I dunno what you expect from relays, but I'd not expect a half decent one to *ever* burn its coil out. They tend to be rated for a given number of operations before failure, which in this case would be many tens of years. However, like anything of this ilk, I'd mount it inside a steel box.
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Lurch wrote (after providing a neat relay-based solution):

Pricey, but not ludicrously so. Units like the Siemens Logo!, the Mitsubishi Alpha, and their friends sell for about 60-70 notes (may be cheaper on Ebay, haven't looked). They're baby programmable-logic controllers, typically 4 independent outputs and 4 or 8 "digital" 240V inputs. Internal logic gives you all the timed-delay, realtime clock, ANDs/ORs/NOTs, and similar low-complexity automation control building blocks you could want. With such a one you end up with momentary-action press switches at each of your convenient control points, often configured to have different control actions for a quick press versus a press-and-hold.
More notes than the OP prolly wants to blow, but hours of harmless geeky fun. (Such a setup controls the outdoor lighting chez nous, with outdoor switches able to turn them on but not off, auto-off around 1 a.m., switchable indoor buzzer-repeater for the front and back PIRs, and the like; and a similar module's in place at work for a flexible, time-of-day/day-of-week-aware hardware access control to control the DC power to the appliance firewall which allows external Internet access for a visitor PC, complete with strobing blinkenlight and final-warning buzzer to remind the dozy pillock using it that their hour of connectivity-time is about to expire ;-)
Stefek
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Richard expressed precisely :

MK used to make one. Try a good electrical wholesalers and if they don't have one get them to specially order one.
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You'll need a DPDT relay with a 230volt coil. Easiest to obtain would be an octal type from the likes of TLC or Maplin.
You strap NO the first pole to NC of the second. And NC of the first pole to NO of the second.
The switch lines of the two way circuit (usually marked L1 & L2 on a two way switch) go (in) to the C and (out) from NO and NO (Or NC and NC)
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Can you change the layout of the circuit so the pull-cord is one of the two way switches rather than an intermediate switch?
Another option would be an impulse relay, and changing all the switches to momentary operating types. This is how multi-way switching is done in some other countries (e.g. France), but I don't know how easy it is to buy impulse relays in the UK. (They change state each time they are operated, and are available in DIN rail mounting form to go in a consumer unit.)
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Andrew Gabriel

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The alternative is to rewire so that the pull switch is (electrically) at the end and one of the other two switches is the intermediate switch. The the pull switch need only be a two-way switch.
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Chris Green

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