====== Switches and lights ======

When it comes to automation of the elecrical system of your home, there are a few types of devices that you can use, and it's better that you clearly understand what you need.

**Warning:** messing with the electrical wiring of your home can be dangerous and you should be __very carefull__ whenever you start opening up electrical boxes or panels. Always disconnect the main power first, and make sure **nobody** turn it on by accident before you are finished!

**Note:** do not attempt to modify your home electrical wiring yourself if you do not feel confident and comfortable in doing so. Ask the help of a professional.

All the following devices can be found for the main wireless technologies used for home automation, which are:
  * ZigBee
  * Z-Wave
  * WiFi

===== Switch, light or plug? =====

There are different main categories:
  * Lights: these are typically light bulbs or LEDs,. You can directly replace your bulbs/LEDs with those. The smart ones will let you change light color, light intensity (dimming), and can be turned on and off remotely. They do not require you to change your home wiring.
  * Plugs: these are pass-trough plugs that you place between your device and the wall plug. They allow for remote turn on and off, and will monitor energy consumption of your device. They are good for dumb items that can only be turned on or off, so lights, space heaters, pumps. They do not require you to modify your home wiring.
  * Switches: they are those rockers/buttons/momentary that you press/touch to turn on or off things. They can be as complex as you like and let you perform actions by physically interact with them, like decouple different lights from the actual on/off button.
  * Relays: often called //switches// (wrongly, and confusing) they are smart devices which goes inside your electrical boxes and acts like **plugs**. They can be remotely controller or physically controlled by standard, non smart, switches. There are way too many types, described below, and they require you to change your home wiring.

=== Smart Lights ===
These look like light bulbs, they usually just replace your existing light bulbs, so they can be installed simply by unscrewing the old one and screw in the new one. They can provide many functions like variable color or intensity. 

When they fail, they are light bulbs after all, they can be pricey to replace.

=== Smart Plugs ===
They are useless to control more advances devices like ovens, microwaves, washing machines and dishwashers: any kind of device that needs manual interaction to operate. On the other hand, they are very useful for on/off devices, like turning on that space heater in the bathroom half an hour before you take a shower, or turn on a floor lamp in the garage after dusk for the cats.

They are very simple to operate: unplug the device, plug the smart plug in the wall socket, plug the device in the smart plug. They usually also monitor the energy consumption of the attached device. As downsides, they might be unplugged by careless people, the device itself might be manually turned off, and in that case forget to turn it on remotely, and they can be bulky, so fitting might prove difficult.

=== Smart Switches ===
The main use for these, in my opinion, is to decouple actions and events. You can add wall switched in this way, and trough those switches you can send commands that you can bind to actions like turning on/off smart plugs or smart lights.

The smart switches add a touch of physical interaction to your smart home. Are they needed? No, can they be useful? Indeed.

There are classical rocker switches, push-buttons and touch switches available.

=== Smart Relays ===

These are often called //switches// as well, because they actually perform the action of a classic switch: they turn on and off something, like a smart plug. The main difference with a smart plug is that they are installed inside your wall wiring, not outside like smart plugs. They are, because of this, safer: nobody can accidentally unplug them, but at the same time more complex to install.

They can also be controller remotely or from a locally attached old-style non-smart switch. You need to be careful about the type of the switch tough: some can only be controller by rocker switches, others can also be controller by push-button switches.

Now, there can be many different types of smart relays:
  * One-way relays: they //cut// only the line to the device, not the neuter.
  * Two-way relays: they //cut// both line and neuter to the device.
  * One wire relays: they require only the line, no neuter is needed to operate the relay
  * Two wire relays: they require both line and neuter to operate the relay
  * Wet-contact relays: this is the normal type. Line is fed to the attached device
  * Dry-contact relays: the device is not fed with line/neuter, good for devices that need dry-contact operation (**not** for lights and such)

Be careful to what you purchase. You should take care that:
  * The smart relay will fit inside your boxes. Do not underestimate this!
  * The smart relay will operate with the wall switch you have (rocker/push/touch)
  * The smart relay will tolerate the amperes of the device (10A? 16A?)