UK I have a stiebel CNS 300 wall heater.

[Henry1266]

Hi Regarding the heater and the 4 wires .Will I be able to put a plug on this heater.
What will I do with the fourth black wire ?
I have never come across this before just need some advice please

 

[SJD]

The manual tells you about the connections:

https://www.heatershop.co.uk/Cache/Downloads/CNS-50-300-TREND-Operation-and-installation-manual.pdf

1 Neutral conductor = blue
2 Live = brown
3 Earth conductor = green/yellow
4 Control cable = black

There are 3 possible ways to connect the appliance:

- Appliance connection without control cable
Unregulated appliance. The control cable is not connected. In this case, insulate the control cable.

- Temperature setback via control cable
To reduce the temperature to the set setback temperature, the black control cable is activated via an external electronic contact (e.g. a time switch).

- Control cable connected to external control unit
The appliance can be connected to any control unit that issues the following waveforms as control signals.
[See table in the manual for more info]