I did this with a relay mounted in a box near the existing light switch connected to the bulb wires in the control unit. The relay contacts are wired via a switch to the existing light switch so you can choose not to have the main lights come on when the door is opened, e.g. if leaving the door open during the day. This worked well until the light circuit failed on. I replaced by a micro-switch in a box over the door operated by the final phase of door closing which is to push the top of the door against the frame. Parts were a few pounds from Maplin.
I also wired a push button in the same box near the light switch to the unit's door operation button so can open from the door to the kitchen.
They do bounce, but it happens too quickly, and the power switched is too low, for it to be a problem. Digital things driven by relays know what to expect and watch them until they've finished bouncing.
It's potential problem that has to be considered in the design.
Yes they do. A contactor is a heavy relay, usually designed usually for starting and running motors. There are other categories. Unless the contacts are mercury wetted or similar, they will surely bounce.
Contactors are a subset of relays. They have normally open contacts, which use the high force of the closed magnetic solenoid to exert high pressure on the contacts so they can pass a high current.
They may also have normally closed contacts, but those only have the return spring contact pressure and are thus rated for lower current.
Can also sometimes have auxilliary contacts for additional low current switching, e.g to activate or lock-out other contactor coils, indicator lights, etc).
A common way to eliminate 'contact bounce' on input switches to digital circuits was to use a non-inverting buffer (a couple of 'spare' inverting gates wired up to act as a non-inverting buffer in many cases) with the output wired to its input connected to common contact of a single pole break before make c/o switch with the other two poles wired to the 5v and zero volt rails respectively in the case of TTL logic levels.
The brief spike of short circuit current to Vcc level did no harm to the totem pole outputs when the switches were operated manually (it would be doubtful whether the switch itself could physically survive being operated by a high speed electro-mechanical actuator going fast enough to raise the duty cycle of these short circuit transients to a dangerous enough level).
It didn't matter that the switch contacts bounced because the very first contact would latch the input state requiring the switch to be operated fully to get the the common to contact the opposite contact and force the latching circuit into the opposite state. Using cheap 'n' cheerful single pole break before make c/o panel switches with a simple self latching input circuit was a neat way to de-bounce control panel input switching signals.
Is exactly the right answer! :-)
In the case of largely resistive ac lighting loads, the electrical erosion that creates pip and crater wear on switch contacts when using a DC supply is virtually eliminated by the use of AC current (as is the required open circuit contact gap by virtue of the current falling to zero a hundred or a hundred and twenty times a second on UK and US supplies respectively).
Controlling even modest levels of DC power can cause contacts to weld closed if contact bounce isn't contained within acceptable levels (much lower levels than required in AC power circuits). Also, what marks off a 'contactor' type relay is the inclusion of a rapid toggling action to reduce arcing time on interruption of current (a vital requirement when switching DC supply voltages) as well as to reduce contact bounce on closing the circuit. For really difficult high amperage, high voltage circuits, the mercury tilt switch type contactor is still a favourite choice when long life and reliability is demanded (no pip and crater erosion issues!).
I have two light switches already, one at either end of the garage. Another poster suggested wiring between the two switch wires with the relay ) I think) - that seemed sensible:
"Much better to use a SPST (Single Pole Single Throw?) relay between the two strapping wires of the existing 2-way switch wiring. That will force the lights on for the time period regardless of the existing state of the lights."
That doesn't matter if the relay is only operated by a one shot flip/ flop timer to give a few minutes of on time overriding the normal two way light switches (and, a rather neat solution in this case). :-)
The only problem though is that if you operate one of the 2 way switches during this relay mediated on period, unless you can readily see the state of the garage light after you've entered the house, you could land up unintentionally leaving the garage light on until the next time you enter the garage.
There are ways to eliminate this risk but it involves a more complicated control circuit requiring the light switches to be replaced by momentary push switches to provide user input to the controller logic.
Yes. Only the OP can decide what really would suit him. Anything is possible.
It never ceases to surprise with things like this what seems perfectly logical to one, is not to another.
Had some relations staying the other day. When I wired this house, I put light switches for the hall and stairs etc, so you could always switch on the needed ones without a detour. The stairs lighting having 5 switches.
If that was 5 stair lighting switches per floor, I'm not surprised! :-)
When we moved into this 3 storey Victorian semi detached house some 35 years ago, I found myself having to completely rewire the lighting circuits (VIR cable hidden away in surface conduits).
When it came to the stairway and hallway lighting, I fitted a dual gang and a single gang 2 way set of lighting switches on the first landing to control the hall, the first and the second floor landing lights.
I still get confused by this trio of switches from time to time. Thankfully, only rarely and usually when I'm not concentrating as I should when intending to light up the top floor landing. Thinking about it, this is odd considering the switches are stacked one above the other with the single gang top floor landing switch placed exactly where logic would dictate, in the uppermost position. :-(
No - five in total for the stair lights. Over 2 1/2 floors. No plate has more than two switches - apart from the one at the front door which has three - one for the outside lights.
And probably switches situated in the best place for the sparks rather than you - if anything like this one. ;-) But it was lead sheathed in the main here.
I'd just discovered grid switches so loved being able to make up whatever I wanted. ;-)
In which case, I assume the luminaries on the 1st and 2nd floor landings aren't independently controlled as mine are (I'm not bragging, just sayin'
- there's a lot to be said for treating the whole hall and stairway as one extended lighting zone that should be illuminated the whole time between dusk and bedtime even way back before the advent of the CFL (let alone today's LED lamps) took the running costs out of the equation).
Thinking about that, I suppose you're right about the siting of the switches being placed to simplify the wiring topology. In fact, when checking the location of the top landing light switch just now to confirm this, I discovered the reason for my occasional confusion with the light switches on the 1st floor landing.
It turns out that I'd misremembered which way round the single and dual gang switches had been stacked. The lower single gang switch controls the hall light, leaving the upper two gang switch plate to handle the landing lights independently. There *is* a logic to the layout, just not the logic I'd misremembered. :-( No wonder I sometimes pick the wrong switch when trying to light up the top landing!
To reiterate, WRONG! The switches are stacked the other way round (single gang lowermost to control the hall light). :-( However, I have a similar arrangement on the ground floor where the top switch is a single gang for the 1st floor landing and the lower dual gang controls the hall and porch lights in a logical arrangement - the RHS switch being nearest the front door controlling the porch light[1].
I only discovered grid switches nearly three decades after re-wiring the lighting circuits (and, shortly thereafter, the rest of the house wiring which was mostly a disorganised mess of otherwise perfectly good condition PVC insulated 2.5mm FT&E in a confusing mix of ring and spur circuits). The discovery was far too late (and expensive imo) to have been of any benefit - the system works just fine as it is thank you very much! IOW, I see too little benefit for far too much time and effort (and expense!) on my part to make it worth the bother. I plan on leaving those pleasures to the next owner. :-)
[1] I fitted an above the front door porch light (underslung 'coach lamp' off a bracket screwed onto the key stone high above the front door) just over 30 years ago which went out of use after fitting an even more elevated 500W halogen security light which made the porch light somewhat redundant.
Apart from a lamp change every 12 to 18 months or so, the first security light lasted so long (over a decade) that the original Porch light rusted so badly, I had to remove its remains from the bracket, leaving the (disconnected) flex dangling about a foot or so from the open end of the bracket's tube where it remained in this state for almost two decades during which I went through a further two security light replacements.
The final security lamp replacement (yet another 500W halogen jobby - LED versions were (and still are) underpowered and over-priced and only a third of the efficiency we had been promised by both Cree and Philips lighting over two and a half years ago on an 18 to 24 month timescale) was only fitted 2 years ago and failed completely after only one lamp change.
Since it was installed so high up on the wall of the house and the promised high efficiency LED security lights *still* hadn't materialised, I decided to finally repair the original porch light earlier this year as a stopgap come backup driveway lighting solution. Even today, the fact that the RHS switch has an actual function still has a novelty value in my mind. :-)
I had a problem trying to work out how I had rendered the dangling cord electrically safe when it came to reinstating this circuit. It turned out I had simply moved the 'live' from the common onto the opposite c/o contact of the light switch. Of course, I discovered this only after lifting floorboards on the 1st landing and the adjoining bathroom to check out the collection of joint boxes that lived there - it seems I had been too clever by half when I'd rendered the circuit safe all those many years ago. :-(
The porch light is a stopgap solution in the sense that I only ever want to replace that damned security light *one last time* when the promised
250 to 300 Lm/W lamps *finally* make it to market to replace all those poxy 67 to 81 Lm/W examples still cluttering up the retail distribution channel (even those 90 to 100 Lm/W lamps that can now be bought from LED lighting specialist shops are "Too (feckin') Little, Too (feckin') Late." as far as I'm concerned).
The only saving grace with the incrementally improving LED 'Light Bulbs' is their ease of fitting into existing interior luminaries, a feature totally lacking in an LED security light where the LED array is a more permanently integrated part of the whole luminary - not a detriment in itself (far from it, one less corrosion prone connector to cause premature failure with a lamp type rated anywhere from 20,000 hours to
50,000 hours) but an extra cost when incrementally upgrading to higher and higher efficiency LEDs as they progress towards the promised 300Lm/W higher output lower heat generation LEDs. I'm hanging on until the LED arrays used in security lights achieve at least a 200Lm/W efficiency rating.
It's not so much the reduction of the electricity bills that interests me (as nice a side effect as that is) so much as the fact that higher Lumen efficiency means less waste heat for a given lumen output will be contributing to the lamp's early demise through overheating of the lamp and its luminary.
That is to say, the freedom to forget the heat dissipation limitations of existing luminaries designed with high temperature incandescent lamp requirements in mind when choosing a modern LED Bulb on the basis of required Lumen output alone. IOW, the need for specially designed for (the current crop of soon to become obsoleted) LED lamp Luminaries will eventually become sidelined by the simple expedient of becoming an antique and unnecessary "Folly". :-)
The 1/2 landing and the first floor landing are on the same circuit. That gives 'spill' to the top of the first flight of stairs and obviously from the 1/2 landing to the main one. The ground floor hall lighting does the main part of the stairs. Although even with downlighters, there is enough spill for safety with either on the stairs. No need to leave them on here.
As I said, mine are all grid switches. So two on a one gang plate. And easy to have one or both of those intermediates. Side by side switches are positioned to 'point' to the main source of the light - or order you'd normally use them.
Happily, this place was so bad it all had to be replaced. And I had a very fixed idea of how I wanted it. And tried to allow for any re-jigging as rooms were redecorated or re-arranged as time went on. But with all internal walls being stud and all floors suspended, easier than most to alter things.
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