Motorised garage door - make garage lights come on via relay?

Folks,
A normal motorised garage door with a control box - Rollixo something or ot her. I've lent the installation manual to father in law.
This control box has a worthless light on it that comes on when you activat e the door either up or down, and stays on for 2 minutes after the door sto ps.
I'd quite like to have the actual garage lights come on instead of this ver y small bulb built into the control box. I suggested a some sort of relay s et-up to father-in-law (an electrician) but he was skeptical and started ta lking about contactors, which I've never heard of.
My understanding of a relay is that they are usually used in low-power situ ations to switch circuits of higher power. So my idea would be to have a re lay somewhere alongside my existing two garage light switches, the relay ef fectively acting as 3rd switch.
Helpfully the connector bar in the control box doesn't have connections for the internal light, so I further envisaged removing the bulb from the hold er and somehow wiring to the actual light fitting to provide the switching in and off connections to the relay, i.e. when the control box puts the lig ht on, instead of the bulb illuminating the relay would energise.
Are you with me so far? Anyone else managed to do this successfully?
Jon
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Contactors are the name used by electricians for relays

To avoid digging into the door control circuit, use a photo sensor to note the light has come on. This can then operate a contactor, possibly with a "delay off" if you want the garage lights to stay on longer than the one in the door mechanism.
Haven't felt the need.
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from KT24 in Surrey, England

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On Wednesday, August 10, 2016 at 10:07:28 PM UTC+1, charles wrote:

I did wonder about that too. Would such a photo sensor be able to tell the difference between the control box light (not very bright) and sunlight? Where the control box is it is exposed to daylight when the garage door is open.
Regards Jon
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On 8/10/2016 10:10 PM, charles wrote:

Wikipedia sort of says that a contactor is a relay for more than 15 amps. I always thought that a contactor was a relay specifically designed for operating an electric motor of perhaps 1/4 HP upwards.
Whatever the exact definition, I'd have said that you were right, you just need a relay (of suitable rating of course).

If the bulb is in a bulb holder, is it *really* not possible to connect to its feed from the back, as it were?

Agreed, but seems like more work to me. Another option might be to put a microswitch at each end of the door travel, and use these to activate the lights. With sufficiently cunning wiring it should be possible to make either switch operate the circuit.

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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).
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Not quite sure how that is any different from a simple ST relay?

Right. Generally, a relay will have the same current rating for NO and NC contacts.

You can get some amazingly complicated relay contact layouts too. Ones which go to a low holding current being quite common, for example.
I've tended to think of a contactor as something more akin to a motor switch, which includes overload protection.
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On 10/08/2016 22:10, charles wrote:

Not much digging required. Find the wires that go to the bulbholder of the built-in lamp, connect the contactor coil to those, use the contactor to switch the lights.
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On Wed, 10 Aug 2016 14:02:07 -0700, Jon Parker wrote:

Look into Solid State Relays; much nicer to use.
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On the face of it it sounds pretty simple. Obviously some care about electrical safety, and you might need an extra transistor to give enough switching current for a relay that is switching mains lighting, so may need a feed from another more capable power supply, but assumedly this is what the motor for the door needs, or is it? I think your father might have been thinking that the door opening voltage might just be enough to seperate a relay or a light on its own, but of course when the Dorr stops,the light would go out, so you might need some kind of latching circuit. It all depends though on how long you want the light to be on. If you want it always on and then goes off when you manually turn it off, then an old fashioned triac on DC and a relay would suffice, but you would need to interrupt the load for ie the relay when you turned off the light. You know I am sure somebody must have thought of this already. Brian
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On 10/08/2016 22:02, Jon Parker wrote:

Use a bayonet connector ((Amazon.com product link shortened) ) to replace the lamp on your door opener, connect that to your contactor and the contactor to your lighting switch. Any problem in the future and you can just unplug the bayonet connector re insert your lamp and your door is as it is at the moment. I'm sure your FIL can provide a suitable box for the contactor.
If your lamp is an ES there are convertors available.
Peter
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On 11/08/2016 08:08, Peter Andrews wrote:

The only gotcha is that since it is a two switch system the relay will need to be a 2 pole changeover to allow it to work with the existing switch wiring. Such mains powered relays are available. eg
https://www.rapidonline.com/good-sky-rk-207a-dpdt-10a-power-relay-230vac-60-1676
12v & 24v ones also available in the same range.
One thought though - might it not be simpler to replace the poxy filament lamp in the unit with a much higher efficiency LED based one?
TBH the dim light never really bothered me. Not sure I want the full workshop illumination coming on when I drive into the garage. YMMV
Regards, Martin Brown
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On Thursday, 11 August 2016 08:46:40 UTC+1, Martin Brown wrote:

The relay will have no knowledge of the existing state of the switches and, if the lights are already on, will turn them off.
Much better to use a SPST 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.
Owain
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On Thursday, August 11, 2016 at 9:20:38 AM UTC+1, snipped-for-privacy@gowanhill.com wrote:

Yes, this is exactly what I want to achieve. Thanks, I'll show this FIL.
Regards Jon
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On Thursday, August 11, 2016 at 9:20:38 AM UTC+1, snipped-for-privacy@gowanhill.com w rote:

isting 2-way switch wiring. That will force the lights on for the time peri od regardless of the existing state of the lights.
Owain,
Just getting round to this project. I have the necessary adapters and screw -in bits to get the electrical connections from the lamp holder to outside the control box where I can work with them.
In your post above you refer to strapping wire, which I think is another na me for 'switch wire'?
I also have been doing some looking for relays, would this simple one do th e job?
http://uk.farnell.com/finder/26-01-8-230-0000/relay-spst-no-250vac-10a/dp/1 455193?mckv=kmyXOTEc_dc|pcrid|78108381549|&gross_price=true&CATCI=pla -131290224789&CAAGID002612229&CMP=KNC-GUK-GEN-SHOPPING-FINDER&CAGPSP N=pla&gclid=CjwKEAjws5zABRDqkoOniLqfywESJACjdoiGH-lh80XVK6jwSavclFO_hIF UX1Py3j_0iO5CgN810xoCNebw_wcB&DM_PersistentCookieCreated=true&CAWELAID120173390000050060
Regards Jon
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On Thursday, August 11, 2016 at 8:46:40 AM UTC+1, Martin Brown wrote:

Thanks for that, bookmarked.

Sadly not. The control box is near the front of the garage as you might expect. I have to reverse in to the garage and it's quite tight as it is and I want proper light so that I can see exactly where I am.
Regards Jon
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Jon Parker wrote:

Is it cheaper to buy a 7in reversing camera for the car?
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On Thursday, August 11, 2016 at 5:05:05 PM UTC+1, Capitol wrote:

Doubtful, but in any case that's not what I want.
Jon
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On Thursday, August 11, 2016 at 8:07:46 AM UTC+1, Peter Andrews wrote:

That's just the job, great spot sir!
Jon
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I always wondered why they had such poxy lights. They seem old fashioned.
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On 11/08/2016 09:57, Jon Parker wrote:

Unfortunately since posting this I have found the manual on line and noticed that the lamp is probably an E14 25w 240v and as I have been unable to locate an E14 connector you will also then need ((Amazon.com product link shortened)70910289&sr=8-7&keywords=bulb+converter+e14+to+b22) to connect to, BUT this combination probably won't fit inside the housing. However assuming you are not concerned about a warranty on the opener and your FIL is an electrician he should easily be able to find a suitable way of connecting a contactor to the unit in parallel with the existing lamp.
Peter
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