Hi folks, I'm new to this site and to electronics generally. I'm looking for advice/validation. I want to install low level embedded path lights (walkover type) on a winding path from a garage to a house approximately 50m away. Id prefer 12v as digging the trenches for mains cable will be exceptionally difficult due to tree roots, etc. I'd like led lights staggered on both sides of the path, not worked out how many yet but quite a lot! I'd like the lights switched by pir switches at the house end and at the garage end - wired together. To avoid digging up the existing path too much I'm thinking I'll have 2 circuits, 1 on each side of the path. I assume I'll need 2 transformers for this ( located inside the garage). Can i use the 2 pir sensors to switch both circuits? Does this all make sense? Anything else I should be aware of or should I do it completely differently!? Many thanks!

 

Should be able to do this with one 12 volt power supply rated high enough to handle the total current of the LEDs
Two PIR sensors modules controlling one circuit using a 3 wire cable and possibly a relay.

 

Should be able to do this with one 12 volt power supply rated high enough to handle the total current of the LEDs
Two PIR sensors modules controlling one circuit using a 3 wire cable and possibly a relay.
View attachment 336593

Hi, thanks so much for responding so quickly. I understand your diagram but does this cover the issue I have with not wanting to dig up the path too much to place LEDs on each side? This is why I thought 2 circuits might overcome this - also thought the cable length would be less and so less loss? Thanks.

 

One separate PIR for each side of the path?
Or each PIR activates just 1/2 of both sides of the path?
Seems the amount of digging would be the same.

 

Sorry, I don't think I've explained myself very well. I'm thinking to reduce the number of times I have to dig up the path when the cable moves to the other side I'll just have 2 cables/circuits each running down one side of the path, both switched by a single pir at the garage or house end. Hope this makes sense!?

 

OK, and while the circuit correctly conveys what will satisfy the requirements it does not show the details,which will be that a pair will need to be in the trench, one on each side of the path. With a bit of extra effort the two sides could be independent, for redundant reliability, in that if one failed the other would still light. Depending on how important the light is, that may, or not, be worth the effort. The redundancy might be two power supplies, one for each side, and then two relays, one switching on each sides lights, controlled by one PIR sensor. One sensor at each end, as requested, would only need a pair of lighter wires, as the one PIR will only control the two relays, just a very few watts.

 

Thanks, I hadn't thought about the redundancy aspect of this. Not a critical requirement but certainly useful!

 

Sorry, I don't think I've explained myself very well. I'm thinking to reduce the number of times I have to dig up the path when the cable moves to the other side I'll just have 2 cables/circuits each running down one side of the path, both switched by a single pir at the garage or house end. Hope this makes sense!?

Like This?

 

Thanks so much, yes this looks absolutely like I was thinking. Could the 12v supply be the same be the same unit for both circuits - leaving aside the point about redundancy and assuming it had the necessary capacity?

 

Like This?
View attachment 336596

Certainly a single supply could support the whole system. That will require knowing what the total load from all of the LEDs will be.
IN addition, if a relay is used to provide control from the end that does not have a power supply, it will allow the use of a much lighter gage of wire for the control signal back to the end with the power supply.
(That suggestion is offered because I don't know what the power requirements of the LEDs are, nor the cost of wire where the TS is located.)
One more thing is that the power supply that I have that is intended for outdoor lighting like that states that it is "for outside use only" , so check the label on your power supply. AND also verify that it delivers DC. My supply provides 12 volts AC.

 

Could the 12v supply be the same be the same unit for both circuits

Certainly with the correct gauge wiring.

 

Great stuff everyone....thanks for clarifying all this. Now for the digging!

 

Great stuff everyone....thanks for clarifying all this. Now for the digging!

Now the fun part starts.
Have you decided on any of the components required?

 

Not decided on the specific components yet - was just clarifying the overall design. Happy to post the component list when when I have decided...

 

Certainly an adequately rated supply can power the whole system. And now, once again, I am suggesting the inclusion of a relay to actually switch the power, and both PIR controls operating that one relay. It will reduce the number of high current conductors, and avoid having the PIR devices having to switch the higher load current, extending their lifespans.

 

That's not going to reduce the number of higher current conductors

 

Certainly having a single relay at the one end will avoid needing a high current wire from one end to the other to the other end, if only one power supply is used. With two power supplies your statement would be correct.

 

There are 2 PIR units one at each end of the path. They both have to have power.

 

The power consumed by a PIR device is much less than the power for all of those LED lights on that long path. 50Mis over 150 feet, and consider that these are not 20mA LEDs. So that is the reason forboth PIR devices to power one relay located at the power supply end. The relay control can be #24 wire, the LED string power would be #18 or #16 wire.

 

The power consumed by a PIR device is much less than the power for all of those LED lights on that long path. 50Mis over 150 feet, and consider that these are not 20mA LEDs. So that is the reason forboth PIR devices to power one relay located at the power supply end. The relay control can be #24 wire, the LED string power would be #18 or #16 wire.

This has merit based on the amperage the LEDs will draw and the ratings of the PIR selected.
I mentioned in post #2 a relay might be required based on the above statement.
Here's the proposed layout using a relay: