In Conjunction With Extensions - ABB Busch 6590U-127-500 Manual Del Usuario

Installation
b. Installation in conjunction with extensions
Any number of pushbuttons (e.g. 2020 US non-illuminated)
can be connected in parallel and actuated against L for
switching and dimming via pushbutton input terminal 1.
Please note the following for pushbutton operation:
- The phase of the extension and the phase of the supply
voltage must be the same and connected to one circuit.
- When laying lines, there must be a sufficient distance
between control lines and load lines (min. 5 cm)
- The maximum line length of the extension lines is 100 m.
- It is not necessary to change the line routing with
existing two-way and intermediate switch circuits.
CAUTION
It is not permissible to illuminate the pushbutton
extension parallel to the switching contact. Use
pushbutton with separate "N" terminal.
GB
14