Question

Why may bus devices only be installed up to 350 m from the choke (power supply unit)?

KNX BasicLearnSystem OverviewMedium
Answer

D — Because the choke plays a significant role in forming the equalization pulse

Correct: The choke helps form the positive equalization pulse, so devices must stay within 350 m of it.

Source

KNX Basic Course Documentation — 12.2 — p. 54

All proposed choices (exam context)
  1. A.Because beyond 350 m the 30 V DC supply drops to zero
  2. B.Because collisions cannot be resolved beyond 350 m
  3. C.Because ETS cannot address devices further than 350 m away
  4. D.Because the choke plays a significant role in forming the equalization pulse
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Last updated: 19 May 2026

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