Hi guys,
I'm at the point where I'm going to install my home automation in my new home. I had planned to install an of the shelf system but now I'm convinced that node-red would be even better. The only problem I have is controlling the outputs, normal on/off and dimmable lights. Most examples that I can find is where node-red is communicating with an excisting system/PLC, but isn't there any solution where a second controller/PLC between node-red and the relays/dimmers isn't necessary. The only option would be low power relays to switching the high power relays (that are certified to install on the 230V electrical system over here). But again, this is 2 relays for 1 output.
You can get relay boards that can connect to a Pi and are rated at 240V. This is just one example I found by googling. They are available with less relays for less money. Make sure you get one that specifically says it will work with a Pi if that is what you are using. Some don't work with the 3.3v capability of the Pi.
https://www.modmypi.com/raspberry-pi/relays-and-home-automation-1032/relay-boards-1033/8-channel-12v-relay-module
Alternatively you can use Sonoff devices which you can flash with Tasmota or other s/w to give very cheap wifi devices that can switch mains voltage.
Thanks for your reply! Indeed I know those options, the problem is, the moment that we put relays or any other devices on our 230V system over here, it has to be certified for it. The problem is that those relays and the sonoff’s aren’t, so we can only use them in low voltage systems or behind a power cord. I think however, that the only option for me is to get a relay/mosfet board and hook that up to the 230V relays. I think that there is a market for I/O devices that directly comunicate with node-red... 
The issue isn't interfacing with node-red, but interfacing with the pi, which direct on the IO pins only has 3.3V available.
However, there may be approved devices similar to the one linked below that can be driven directly from a pi, provided the device is located close to the pi. Otherwise, as you say, you will have to use an interface board of some sort.
As @Colin says, Node-RED communicates only with the hardware on which it runs. That could be a desktop, laptop or Android tablet as well as a pi. If you were more specific about your choice or options for controlling mains power, we might be able to suggest interface possibilities and look at trade offs between simplicity, cost, flexibility, etc.
If your looking to do remote to the pi relays, then "Superhouse" has a neat solution which uses a Arduino and a relay shield that controls contactors in a consumer unit (which you probably could find that are certified). You would then control the boards via MQTT.
