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Adding automation to pre-existing intermediate lighting switch schemes
This article outlines how to add automation to the intermediate switching schemes for landing and hall lights that are found all over the world. |
Automating Intermediate Switching
All over the world intermediate switching schemes have provided a simple way of controlling hall and landing lights from several locations. This is based on the ways that homes are used, sometimes you need to switch from just outside a bedroom and other times at the bottom on the stairs on the way up.
Here's the schematic of an intermediate switching scheme:
Why automate?
These days, halogen lighting has become more popular, it gives a good light source and decoratively works well. The only downside is energy, hall stairs and landings are second only in their lighting demands to kitchens.
It is also the hall-stairs-landing lights that are likely to get left on by children - no matter how much education the domestic leaders put in place. Using automation we can get a number of advantages:
A mechanism for automatically turning the lights off without disturbing the function of the intermediate lighting scheme
The opportunity to create PIR driven lighting
The ability to integrate into security systems
The ability to time how long the lights have been on
Adding the automation
To sucessfully add automation we need to achieve two goals:
The ability to control the circuit
The ability to monitor the circuit
Fortunately in this case it is easy to implement using two relays. Consider:
Here we use one DPDT relay to act as an intermediate switch, the other acts as monitoring. Note that the two have very different coil voltages:
The control relay has a 12VDC coil
The monitor relay has a 230VAC coil
Example installation
To make it easy for the electrician to understand, we asked for an extra intermediate switch to be installed in the loft space. This then allowed a clear access point. We simply removed the switch and added the two relays:
Notes
Note that we've kept the two relays at opposite ends of the box, this is to keep the clarity regarding voltage levels and functions.
You'll see a small metal can on the top of the box. This is for an entirely different function. It measures the light levek in the loft - this in turn lets us know if the loft lights have been left on!
Here's the WebBrick configuration view:
and here's the consolidated view from our upcoming HGA product:
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