This is a project, I've been meaning to do for a while but, having dug up most of my garden as part of my 'Smart Pond' project and 'Smart Garden Lounge' project, it made sense to put in the ducting and infrastructure to finally do it properly too.

As with most of my contextual smart home, I'm aiming for invisible sensors and devices where possible and a zero touch user experience.

When I looked at the underside of the window sill, I could see a channel along the whole length, 36mm wide and 15mm deep. This was just perfect to fit some 16mm × 16mm trunking (on the inside) and some 90° aluminium profile up against it, to allow an LED strip to be mounted at 45°, pushing the light both out and down.

I used an external frame sealant to fix both the trunking and the aluminium profile. The ducting carries wires for the power and also a 4-core alarm cable for the beam break sensor.

The aluminium profile comes in 1m lengths, so I've joined three together. It also comes with end caps.

Although the LED strip can't be seen, I'm using a semi-clear diffuser to soften the light and to protect the LED strip from the elements. I'm using a warm'ish white 5m long LED strip (cut down to 3m) and it is 8mm wide. It requires a 12V dc power supply and the power required is about 1.5A for the whole 5m (16W) but, I'm using less than 3m (so about 0.9A / 10.8W).

The shed path light is triggered by many things but I'm primarily using a beam break sensor because these provide the most accurate and timely detection, with very low latency. They are also the best sensors in terms of lack of false triggering. These are mounted at the end of the path, so simply walking towards the shed will light up the path.

Some people use PIR sensors (motion sensors) but, these will give a much poorer user experience in this type of application, will be falsely triggered by wind, etc. and have a much wider field of view.

Before I installed the beam break sensors, I opened them up and used insulation tape to cover up the bits I didn't want covered in PCB lacquer. The PCB lacquer is over-kill really but it basically protects the sensor better from moisture and should make them very reliable.

This is the beam break sensor receiver and it is mounted it at about hip height to give best detection performance but also to allow it to be protected from the elements by the window sill. Some 4-core alarm cable runs to this unit. It has a small internal relay (which can just about be heard in operation), to switch a 12V signal.

This is the beam break sensor transmitter mounted on a wooden post, opposite the receiver. This allows me to hide the wires inside the post. It requires just a 12V dc power source.

Both modules have an O-ring to prevent water ingress via the cover. You will notice, that I've also used black silicon sealant over the front screws on these modules, to protect them from the elements too.

I was really pleased with the way the shed path light turned out, so I used some of the spare LED strip in a 50cm length of 10mm flat profile above the shed door as well. It's just the right width to sit nicely under the 'eave' of the shed roof.

Both are connected to an Arduino Mega 2560 inside my shed, which uses a unified communications protocol to communicate with my Home Control System and send and receive events.

I'm using my Smartisant Arduino Shield SHLD1 to connect the sensors.

My Smartisant Arduino Header HEAD1 allows up to three 8-channel input or output boards to be easily connected to the Arduino.

For the 12V lighting I'm using my Smartisant 8-Channel Output Board OP2.

Testing it at night shows it to be plenty bright enough and a nice colour temperature too. This photo was taken before the paving stones were put back. You can see that the far end of the path is not lit up. This will be done using another smart light over the door. This will make it easier to put the key in the shed door lock.