For how long are outgoing and return conductors permitted to run in the same cable assembly?

The maximum length for outgoing and return conductors to run in the same cable assembly is established to minimize the risk of signal interference and ensure proper system performance. When conductors are grouped together, particularly in a fire alarm system, maintaining a defined length helps manage the electromagnetic interference (EMI) and ensures that the integrity of the signals being transmitted is preserved. Running them together for too long can lead to issues such as crosstalk, which could negatively affect the operation of the fire alarm system.

A maximum spacing of 10 feet is a standard guideline that ensures the balance between cable length and the need to keep different circuits separate enough to reduce interference. This limit is in line with industry practices aiming for reliability and performance in installations. Therefore, this guideline is crucial for maintaining the safety and functionality of fire alarm systems.