DIY LED strip stairs

[designabc123]

Hello everyone!

I'm looking for some guidance regarding installing some stairs lighting. I have quite limited knowledge regarding all stuff electrical, so please forgive my ignorance.

I just moved into a new house and I want to add LED strips under the nosing of each step. The way I have the stairs set up force me to run cables along a channel I have on just one side of the stairs, all the way up. The stairs do a U turn with a landing area in the middle.

I want to add motion sensors at the bottom and top of the stairs and I want to keep the wires running up and down the stairs and the soldering to a minimum (I'm not a great solderer). I created a amateurish wiring diagram of the whole setup and I'd really appreciate you guys telling me if this would work, or if I'm way off.

Thanks in advance!

 

[plugsandsparks]

Whether this will work or not depends on what products you are buying. The diagram suggests LED strip connected in series, i.e. Constant current mode. It also suggests the PIR is also in the same circuit from the driver. I have personally not come across such a way of connecting PIRs this way as the ones i have used require a constant voltage.
Before you ask how should it be wired, i refer to my first point.

 

[SJD]

As mentioned by plugsandsparks, you have wired the LEDs in series. You can get LEDs that are wired like that (constant current, don't recommend them for this application), but much more likely you'll want 12V or 24V constant voltage types, which are wired in parallel.

The PIRs (at 230V av) need to switch the driver(s), which then generate 12V or 24V dc.

 

[designabc123]

Thanks for your replies guys! My issue with having the LED strips connected in parallel is the amount of cables I would have to fit into the channels I have on the stairs, which are probably around 2 cm wide and 1 cm tall. By the time I get to the top stair and have to run cables to the power supply from there, I would have got to 15 cables by then (I have 15 stairs). So I really need to use a series connection. What would be the risks by doing this? Voltage dropping?

 

[plugsandsparks]

There are no risks, most of my LED installations are in series. What you need is bare LED strip with a specified current for full brightness, this could be 200mA, 350, 500, 700 etc etc
You need to know the wattage of the strip in total, thats measuring the length of all the strips and using the manufactuers data for watts/metre or try it out on a test bench first.
Then you need to purchase the appropriate driver based on the current mentioned above and the total wattage of all the step lights. Now the PIR could be a simple 12V type but the probability that this will work as per your cct is very slim. So either get a 12V PSU for the PIR or as mentioned use a 240V type as typically used in houses.

Its for all the reasons above that manufacturers make LED strip as constant voltage where you can simply cut to length what you need but of course you are back to parallel connections again.

 

[SJD]

If you use LEDs wired in series, then if one fails open circuit, the whole series will go dark. And you'll need to fault-find to work out which one has failed. Whereas if you have constant voltage LEDs, and one fails, it will be obvious - the one that has gone dark while the rest are still illuminated.

 

[designabc123]

Thanks a lot for all your input guys! I see how the series connection can be problematic and hard to troubleshoot if anything happens to one of the LED strips, so I think a parallel connection is much better, as you suggested. The only thing that's not clear to me is, and please excuse the novice question, why 12V motion sensors wouldn't work. I'm sure there are advantages to the 240V sensors but I assume that using this type would also require much thicker wire to run up and down the stairs and that would make hiding the wires impossible, as the channels I have for the cables to run through are not big enough. I attached another diagram with my ideal wiring setup.

 

[Avo Mk8]

You show the 'Landing' led strip as longer than the others. I'm not sure series connection will work properly unless all the strips are the same length. I would favour constant voltage for this project.

I think your diagrams show more wires than are needed. Assuming the pir detectors that you choose will just switch the +ve supply, you can simplify the -ve wiring.

And I wonder if it legit. to wire two pir sensors simply across each other. When one turns on it will feed power back up the output of the other, which might damage it - or maybe not. Maybe someone can advise?
[automerge]1601372035[/automerge]
Looks like you can wire two pir sensors across each other - at least this type:

How to Install Motion Sensor LED Stair Lights | Knowledge Base | Super Bright LEDs

www.superbrightleds.com

View: https://www.amazon.co.uk/BTF-LIGHTING-Function-Control-Controller-Lighting/dp/B07XJSNNB9

 

[designabc123]

You show the 'Landing' led strip as longer than the others. I'm not sure series connection will work properly unless all the strips are the same length. I would favour constant voltage for this project.

I think your diagrams show more wires than are needed. Assuming the pir detectors that you choose will just switch the +ve supply, you can simplify the -ve wiring.

And I wonder if it legit. to wire two pir sensors simply across each other. When one turns on it will feed power back up the output of the other, which might damage it - or maybe not. Maybe someone can advise?
[automerge]1601372035[/automerge]
Looks like you can wire two pir sensors across each other - at least this type:

How to Install Motion Sensor LED Stair Lights | Knowledge Base | Super Bright LEDs

www.superbrightleds.com

View: https://www.amazon.co.uk/BTF-LIGHTING-Function-Control-Controller-Lighting/dp/B07XJSNNB9

Thanks Avo Mk8, this example you shared is very similar to what I'm trying to do, and it looks like they're using a very similar method to what I had in mind. You mentioned that I have too many wires. I was looking at the example diagram and mine and it looks the same to me, am I missing something? I just saw an error were I had wires going to the landing strip twice, which I removed in the attached, but other than that I don't see any other difference. Please correct me if I'm wrong.

 

[Avo Mk8]

Designabc - I think what you've drawn should work using those pir sensors.

Sorry to confuse you with my comment. Before I saw and posted that particular sensor, I was thinking that a typical sensor might have its 0v (black) connection common between its power in and its switched output, in which case linking the black 'in' and 'out' of both sensors means you can do without the second black wire going up the stairs! But I don't know if that is true for this particular sensor, so best to stick with your wiring.

You will need to work out, from the total length of led strip you need, and it's current draw, what the current rating for the psu should be.

Best wishes for the project

 

[designabc123]

Designabc - I think what you've drawn should work using those pir sensors.

Sorry to confuse you with my comment. Before I saw and posted that particular sensor, I was thinking that a typical sensor might have its 0v (black) connection common between its power in and its switched output, in which case linking the black 'in' and 'out' of both sensors means you can do without the second black wire going up the stairs! But I don't know if that is true for this particular sensor, so best to stick with your wiring.

You will need to work out, from the total length of led strip you need, and it's current draw, what the current rating for the psu should be.

Best wishes for the project

Thanks for clarifying, I think I know what you mean, as if I had the 240V PIR sensor there would have been three cables (one being shared), but I think that the 12V one needs 4 cables.

I will test out the setup "on flat ground" first to see if it actually works and share the results, in case anyone will be interested in this setup in the future.

Regarding the PSU, I have a kit that came with 15m of strip LED lights and included the PSU. I assume that their included PSU should be able to power all the LEDs, as it's in the same package. But because I'm adding the two PIR sensors, do you think that will require a higher rated PSU?

 

[Avo Mk8]

The current draw of the sensors is likely to be small in the grand scheme of things. I think you will be fine using the psu you have.
(if you have, or can borrow, a multimeter, you could check what current a sensor takes - I imagine only a few 10's of mA, if that)

 

[designabc123]

The current draw of the sensors is likely to be small in the grand scheme of things. I think you will be fine using the psu you have.
(if you have, or can borrow, a multimeter, you could check what current a sensor takes - I imagine only a few 10's of mA, if that)

That's great, I do have a multimeter and will measure the sensor's take. Thanks so much for helping out!
[automerge]1601397352[/automerge]
That's great, I do have a multimeter and will measure the sensor's take. Thanks so much for all your help!

 

[Lucien Nunes]

Agree with most of the above. The PIR will normally only be switching one pole of the supply, therefore the other will be common between input and output. Running up the stairs will be three conductors - feed, switched feed and common, with each strip tapped into switched and common of the main run and all three terminating at the far PIR. Note that some electronic LED controls switch the negative, which would make the common the positive.

You can see some of my ideas about tapping a small 12V cable neatly into a run in posts #12 & #15 here:
Tapping into a run

 

[designabc123]

Thanks for the reply Lucien, unfortunately I don't have access to your post. I'm probably too new on the forum.

 

[designabc123]

Good news everyone, the setup with the two PIR sensors and the LED strips connected in parallel worked. The only small thing that is not ideal is the fact that when the second sensor is triggered after the first one already turned the lights on, the LEDs closer to the second sensor become a bit brighter. I imagine that as the voltage drops a bit from the first LED to the last, triggering the second sensor while the lights are already on reverses the direction of the power (the last LED gets power first). It's not a huge difference and I can definitely live with this setup. Thanks to everyone for your guidance.

 

[Avo Mk8]

Hi designabc
if you were to use thicker red & black power wires up to the top sensor, or maybe try another pair of wires in parallel, you might lessen the effect you mention.
Pleased to hear it's all working.

 

[designabc123]

Hi designabc
if you were to use thicker red & black power wires up to the top sensor, or maybe try another pair of wires in parallel, you might lessen the effect you mention.
Pleased to hear it's all working.

Thanks for the tip! It's a very slight difference and I've already done so much with this setup as it's not worth removing the old wire and doing it again, but I'll definitely know for my next PIR + LED project.