# Need help with project, garage controlled by light switch

#### Sigma229

Joined Apr 17, 2019
32
Hello,

I am trying to find out how to make a light work the way I want.

What I would like to do is as follows.
I have a light in a garage controlled by light switch and I want to make it so if a door opens it turns on said light.
It's not the main door or I would simply add a motion light switch.

I want the light to turn on if one of the overhead doors open and stay on until door closes.
But I also want the light switch to stay working in the garage except not shut off the light if overhead doors are open.
Where I live have 120vac.

I thought of using relays and low voltage magnetic door switchs but am unsure of how to wire them and keep it safe.
Just in case someone tries using light switch if light is on from Overhead door being open.

If there some premade relay for such a project or how would I go about it.

Sigma

#### AlbertHall

Joined Jun 4, 2014
12,070
Welcome to AAC, @Sigma229
There are door switches which you can mount so they are operated by the motion of the door and which are rated for mains voltages so no relay is needed. You could then simply connect the door switch in parallel with the existing switch and it will work as you want.

These are push to break switches so they should be set so the door pushes the button when the door is closed.
https://www.amazon.co.uk/cupboard-light-switch/s?k=cupboard+light+switch

#### Sigma229

Joined Apr 17, 2019
32
Welcome to AAC, @Sigma229
There are door switches which you can mount so they are operated by the motion of the door and which are rated for mains voltages so no relay is needed. You could then simply connect the door switch in parallel with the existing switch and it will work as you want.

These are push to break switches so they should be set so the door pushes the button when the door is closed.
https://www.amazon.co.uk/cupboard-light-switch/s?k=cupboard+light+switch

Hello AlbertHall,

Thanks for fast reply to my questions, I really appreciate it.

I thought of mains door contact but to meet code it/they cant be used.
I have to use low voltage contacts 5-24v as a trigger.

As for motion lights, I tried a couple but since garage is unheated and it hit -40c/f in winter the motion detectors did not always work and they did not work if people wore puffy jackets.

Thanks
Sigma

#### AlbertHall

Joined Jun 4, 2014
12,070
You could use those switches at low voltage to operate a relay to achieve the same thing.
Edited for sense.

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#### Sigma229

Joined Apr 17, 2019
32
Hello,

Ok I never thought of that.

Thanks
Sigma

#### Pyrex

Joined Feb 16, 2022
13
Hello,

Ok I never thought of that.

Thanks
Sigma
all the switches on the doors to be connected in parallel. Check the state of the switch- it must be open, when the door is closed

#### vu2nan

Joined Sep 11, 2014
253
Hi Sigma229,

Here's the schematic.

Nandu.

#### Sigma229

Joined Apr 17, 2019
32
Hi Sigma229,

Here's the schematic.

View attachment 270808

Nandu.
Hello Nandu,

Thank you very much for the circuit and help, I really appreciate it.

I will post back once I complete the project.

Thanks again.
Sigma229

#### AnalogKid

Joined Aug 1, 2013
10,096
Typical magnetic reed door switches are normally open. When all doors are closed, all switches are closed. In the post #7 schematics, that means that K1 will be close and the light will be on when the big doors are closed, not open. This is the opposite of the req in post #1.

To correct this, the K1 contacts must the normally closed contacts. In this way, the relay will be energized and the contacts will be open when all doors are closed. When any door opens, the contacts will close and the light will come on. Here is a relay module with both NO and NC contacts.

https://www.ebay.com/itm/313976706671?hash=item491a78566f:g:KaEAAOSw7m9bIPpu

But wait - here is a relay module with a selector for either high or low signal level operation.

https://www.ebay.com/itm/185209220035?hash=item2b1f546bc3:g:qGUAAOSw71xZoNIO

If you are stuck with a SPST, NO relay as shown in the schematic, another way to fix this is to use reed switches that are normally closed (or are SPDT, with both NO and NC contacts). These are less common, more expensive, and in my experience not nearly as good for long-term reliability. Still, they do eliminate the need for any circuitry.

If you want to stay with normally-open switches, and do not want the relay coil energized almost continuously 24/7, then a 1-transistor circuit will invert the relay operation. This is what is going on in the second module link.

ak

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Joined Jan 15, 2015
6,701
I have several Sentrol 1087T series switches laying around which offer Com N/O N/C so you have a choice of N/O or N/C. I guess they are now UTC Interlogix (Formerly GE Security/Sentrol). When using magnetic reed switches something to consider is the switch ratings. For example the switch series I referenced:

Technical Specifications:
• Voltage: 30 VAC/VDC max.
• Current: 0.25 A max.
• Power: 3.0 W max.
• Loop type: Open or Closed
• Electrical configuration: SPDT
• Dimensions (WxHxD): 2.5 x 0.50 x 0.56 in. (64 x 13 x 14 mm)
• Housing: Flame retardant ABS plastic
• Color: Gray
Max voltage AC or DC is only 30 volts and maximum current is only 250 mA. Those numbers are pretty common for reed switches like this. Typically a switch/magnet kit was about $10 ~$15 USD.

Ron

#### MisterBill2

Joined Jan 23, 2018
12,402
There are many varieties of limit switches around and many of them are rater for mains voltages and enough current to power a few lights. And as they are for industrial applications they are completely enclosed and have threaded ports for conduit , either flexible or not. So certainly they can satisfy any code requirement. With that scheme there will be no need for a relay and relay power supply and enclosure for them. But you will not find them in most home improvement stores or most hardware stores. Industrial supply or industrial surplus stores will have them. The other benefit is that they usually have both normally open and normally closed contacts.

#### eetech00

Joined Jun 8, 2013
3,210
Hello,

I am trying to find out how to make a light work the way I want.

What I would like to do is as follows.
I have a light in a garage controlled by light switch and I want to make it so if a door opens it turns on said light.
It's not the main door or I would simply add a motion light switch.

I want the light to turn on if one of the overhead doors open and stay on until door closes.
But I also want the light switch to stay working in the garage except not shut off the light if overhead doors are open.
Where I live have 120vac.

I thought of using relays and low voltage magnetic door switchs but am unsure of how to wire them and keep it safe.
Just in case someone tries using light switch if light is on from Overhead door being open.

If there some premade relay for such a project or how would I go about it.

Sigma
HI

I recently installed shop lights in my garage and, as an after thought, wanted them controlled by my recently installed occupancy sensor. I bought a wireless outlet adapter and control it with the Occupancy sensor to operate the lights. Works great. The manufacture (Levitron) also sells wireless door sensors that can operate with the wireless occupancy sensor. You can automate the behavior of the devices using their phone app.

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#### Sigma229

Joined Apr 17, 2019
32
HI

I recently installed shop lights in my garage and, as an after thought, wanted them controlled by my recently installed occupancy sensor. I bought a wireless outlet adapter and control it with the Occupancy sensor to operate the lights. Works great. The manufacture (Levitron) also sells wireless door sensors that can operate with the wireless occupancy sensor. You can automate the behavior of the devices using their phone app.
Hello,

Thanks for the information and help.
I will take a look online to check out what you mention.

Thanks
Sigma

#### metermannd

Joined Oct 25, 2020
309
I've been told about a setup where instead of conventional 2-way switches, the switches are 3-way, and one pole is wired to a 'master' switch so if that 'master' switch is activated, you cannot turn off the lights.

#### MisterBill2

Joined Jan 23, 2018
12,402
I've been told about a setup where instead of conventional 2-way switches, the switches are 3-way, and one pole is wired to a 'master' switch so if that 'master' switch is activated, you cannot turn off the lights.
That is commonly known as "miswiring the 3-way switches."

#### metermannd

Joined Oct 25, 2020
309
This setup apparently was used in a store somewhere in the south, where the owner lived above the store.

If he heard something amiss after hours, he just had to throw the master switch before going downstairs. By then, the flicker of lights from someone trying to turn them off would give away their location. Probably not code compliant (the friend that told me about it had the job of taking out the master switch and the ancient contactor that was connected to it).

Still, I mentioned it as something similar might be a possible solution for OP's needs.

#### MisterBill2

Joined Jan 23, 2018
12,402
It certainly is possible to have 2o of the 3-way switches and a master on switch that has precidenc. So that is one option.
Low voltage control wiring and a relay intended to interface with mains voltage wiring is also an option, I have one working in my house. Those relay control packages are also available wwith an internal transformer so they can be a one-piece control And the security type magnetic switch can work very well, just set it up for the overhead door open position instead of the closed position. Low voltage wiring is a lot easier and less expensive as well.

Joined Jan 15, 2015
6,701
I've been told about a setup where instead of conventional 2-way switches, the switches are 3-way, and one pole is wired to a 'master' switch so if that 'master' switch is activated, you cannot turn off the lights.
The cartoon version would look similar to this but in this diagram both a two way and three way switch are employed. If the top switch (S3) is closed it matters not what position the three way switch (S1 & S2) is in. The lamp will be on.

S1 and S2 are off the shelf SPDT switches while S3 is a SPST switch. In a sense S3 acta as an override switch overriding S! and S2.

Ron

#### MisterBill2

Joined Jan 23, 2018
12,402
It is simpler to connect the master switch ween the two poles of either switch. Same effect and less wire.