Where must splices of existing fire alarm cable be secured to comply with NFPA 70?

The correct answer is that splices of existing fire alarm cable must be secured inside a listed box or enclosure to comply with NFPA 70, also known as the National Electrical Code (NEC). This requirement is important for safety and reliability in fire alarm systems, as it ensures that any splices are adequately protected from physical damage and environmental factors. A listed box or enclosure provides a defined and regulated environment that can shield electrical connections, thereby reducing the risk of shorts or corrosion over time.

Using a listed box also allows for proper access for maintenance and inspection, which is essential in fire protection systems to ensure they remain operational and effective in the event of an emergency. The NEC outlines specific standards for enclosures to ensure that they are appropriate for the type of wiring used and the conditions under which they operate.

While securing splices inside a conduit can provide some level of protection, it does not always meet the unique requirements for fire alarm systems as specifically described in the NEC. Similarly, options like securing splices outside the building or above a drop ceiling do not provide adequate protection or compliance with the code, as these areas may not comply with the standards for fire alarm system wiring.