Fire protection (PLFA) cables can share the same cable tray with low-voltage or communication cables if installed according to NEC 760.139, using proper separation and installation practices.

Code Compliance

According to NEC 760.139, two or more power-limited fire alarm circuits (PLFA), communications circuits, or Class 3 circuits are permitted to occupy the same cable, enclosure, cable tray, raceway, or cable routing assembly . This means that fire alarm cables (Type FPLP) can legally share a tray with low-voltage communication cables (e.g., Cat6A, CMP), provided the installation follows the code requirements.

Separation and Safety Considerations

Even though sharing is allowed, physical separation is recommended to reduce electromagnetic interference (EMI) and prevent potential signal disruption . Best practices include:

• Using divider brackets or compartmentalized trays to separate different voltage classes within the same tray.
• Maintaining a minimum spacing, often suggested as 6 inches, between fire alarm and communication cables when dividers are not used .
• Ensuring that all cables are listed or labeled by a Nationally Recognized Testing Laboratory (NRTL) for the environment in which they are installed .
• Avoiding parallel runs of high-voltage and low-voltage circuits without proper shielding or separation to prevent cross-talk or interference .

Practical Installation Tips

• Tray type and configuration: Ladder, ventilated trough, or solid-bottom trays can be used, but the tray must support the combined weight and allow proper cable management .
• Securing cables: Use appropriate cable ties or fasteners to maintain spacing and prevent cables from shifting within the tray .
• Inspection readiness: Proper separation and labeling help ensure compliance during inspections and reduce the risk of costly rework .

Summary

While it is permissible under NEC 760.139 for fire alarm cables to share a tray with low-voltage communication cables, it is strongly recommended to use dividers, maintain spacing, and follow proper installation practices to minimize EMI, ensure safety, and comply with inspection requirements . This approach balances code compliance with practical considerations for reliable and safe cable management.