Which of the following is not a permitted exception to circuit separation requirements?

• A. An unlimited cable drop to a single appliance
• B. An unlimited cable drop to multiple appliances
• C. A limited drop to a single appliance
• D. Shielded cable in duct

Answer: (A)

Circuit separation is about keeping fire alarm circuits separated from other electrical circuits to prevent interference and maintain reliability. Some exceptions are allowed, but they come with precise limits to prevent compromising that separation. An unlimited cable drop to a single appliance isn’t a permitted exception because letting the run extend without a defined boundary means the separation isn’t guaranteed along the length of the wire. That open-ended path could bring non–power-limited activity or cross-talk into other parts of the system, defeating the purpose of maintaining distinct circuits.

The other options reflect controlled exceptions: a limited drop to a single appliance keeps the path short and contained, preserving separation while still allowing practical wiring; shielded cable in duct uses shielding and a physical barrier within a duct to reduce interference; and an unlimited drop to multiple appliances is allowed in contexts where the shared run remains within the established separation requirements and is properly protected.