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Product Support

How Many Power Supplies do I Need for a KNX System?


Every line must have its own power supply including any area or backbone lines. The size of the power supply is determined by the number of KNX devices on each line segment and as the consumption of each devices can vary, this must be checked when designing a system. 


Power supplies come in 80mA, 120mA, 320mA and 640mA versions and some have secondary, un-choked outputs for devices that have a high current draw. If the secondary output is used, it needs to be considered that, in most cases, the rated current applies across all outputs not each individual output. 


It is possible to have more than one power supply on a line but it is critical that the maximum number (64) of bus devices per segment is not exceeded. Check manufacturer specifications for more information.

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