Smart Home Wiring Connectors

When it comes to wiring up your smart home, there is a lot more to think about than just the wired IP network, especially if you have a hybrid technology smart home.

Molex Connectors

To keep things really simple, we standardised on the KK 254 Connector System. These are cheap, flexible and extremely reliable.

These connectors consist of 3 parts:

The male PCB header, exposing the pins. These fit into a series of holes in a PCB with a 0.1" (2.54mm) spacing.
The female crimp housing. These hold the crimped terminals and you only need to fit those that are required.
The crimp terminals that are crimped onto the end of the wires. For added security and reliability, we always solder these as well as crimping them.

These connectors are available in various formats. We use the vertical latching (with friction lock) version. Where vertical space is at a premium, it is possible to use 90Æ variants.

Note: These connectors are designed to carry a maximum of 4A and require fairly small wires. We typically use 7/0.2 equipment wire.

Crimp Terminals

These crimp terminals are fixed onto the end of wires using a crimp tool.

Warning: In our experience, it is essential that you use a high quality crimping tool in order to get reliable connections. We also solder them as well.

2-Way Molex Connectors

2-way Molex KK 254 connector.

3-Way Molex Connectors

3-way Molex KK 254 connector.

4-Way Molex Connectors

4-way Molex KK 254 connector with friction lock. These can be used for both input and output and with both 5V and 12V sensors or devices. We also use them for both digital and analogue inputs.

Note: Some Arduino processors and processors like the ESP8266 have analogue inputs that operate at 1V or 3.3V. We use the '5V' line/pins at these lower voltages when connecting sensors. Check the analogue input range carefully!

With these 4-way connectors, we have standardised on the following pin assignments.

Note: In some applications where we know the installation is permanent, we will bypass these 4-way connectors and solder sensors or devices directly to a PCB. This reduces the flexibility and ability to easily swap out failed components but, it does reduce the cost of each installation.

10-Way Dual In Line (DIL) Connectors

To connect a lot of our together, we use a 10-way DIL connector (2 rows of 5 pins). This is exposed on our various PCBs using a 10-way shrouded header.

This connector provides +5V, GND and 8 IO pins.

We have standardised on the following pin connections: pin 1 to pin 8 are the channels 1 to 8, pin 9 = GND and pin 10 = +5V.

To connect two 10-way connectors together, we use a 10-way 'straight through' ribbon cable. This means that the same pins are connected together at each end.