Low Voltage Wiring Cable Tray

Yes, low-voltage wiring can be run through cable trays, provided proper separation, fill limits, and cable types are observed according to NEC and industry best practices.

Code Compliance and Cable Types

Low-voltage wiring, typically defined as cables carrying 50 volts or less, such as data, communication, security, and building automation cables, is permitted in cable trays under the National Electrical Code (NEC) sections 318 and 392 . Common cable types used in trays include PLTC, ITC, MC, TC, and communication cables, as well as fiber optic and fire alarm cables . NEC allows multiconductor cables rated 600 volts or less to share a tray, but power and signal cables must be separated to prevent interference, typically by a fixed barrier or a minimum 2-inch separation .

Tray Selection and Installation

Cable trays come in various types, including ladder, ventilated trough, and solid-bottom trays. Ladder trays are preferred for low-voltage installations because they provide excellent ventilation and easy cable management, while ventilated troughs offer moderate support, and solid-bottom trays provide maximum protection but are more restrictive . When installing low-voltage wiring, it is important to account for cable diameter, quantity, weight, and bend radius, especially for fiber optic cables, to avoid stress and signal degradation .

Fill Limits and Separation

NEC 392 specifies fill limits based on the cross-sectional area of cables relative to the tray's usable area. For low-voltage cables, the practical rule is to avoid overcrowding and maintain proper spacing for heat dissipation and future maintenance . In industrial or commercial settings, signal and power cables are often run in separate trays or on different tiers, with power cables typically on top and signal cables below, maintaining at least 12 inches of vertical separation when possible .

Practical Considerations

Running low-voltage wiring in cable trays offers advantages such as organized routing, easier maintenance, and scalability for future expansion . It is recommended to plan for a 20–30% growth margin in cable quantity and weight, and to follow proper grounding and bonding practices if the tray is used as an equipment grounding conductor . For installations near high-frequency devices like VFDs, additional separation or shielding may be necessary to prevent electromagnetic interference . In summary, low-voltage wiring can safely and effectively be run through cable trays when appropriate tray type, fill limits, separation, and cable management practices are followed, ensuring both code compliance and long-term system reliability .