Page 104 - Basic Course

KNX BASIC COURSE

9 Bus cables in wall boxes

Mains and bus wires should be installed either in:

 Separate installation / wall junction boxes or;

 Common installation boxes with a partition, guaranteeing the required clearance / creepage
distances

Figure 11: Bus cables in wall boxes

SELV circuits require double or reinforced insulation (protective separation) between
mains and bus cables, i.e. unsheathed bus cable cores should never be in contact with
mains cables.

Junctions can be installed:

in separate boxes or
in a common box with a partition, ensuring 5,5 mm clearance and creepage distances
e.g. towards 230 V / 400 V AC TN/TT networks in office buildings.

Home and Building Management Systems KNX Association
KNX TP Installation Installation_E1213c 14/28