One of the greatest benefits of central vacuum systems is that the power unit is turned on and off automatically. Every power unit has an on/off switch that is activated by completing a circuit at the inlet valves. Simply inserting the hose in the inlet valve turns on the power unit.
To facilitate this, low voltage wire must follow the tubing system. At the junction of a branch line and the trunk line the wires can be spliced together as demonstrated in the figure.
There must be an uninterrupted route from each inlet valve to the power unit. The wire should be attached to the tubing with the wire ties at least every four feet.