Code Compliance Summary:

✅ 1. Emergency System Circuit Independence – NEC 700.10(A)

“Wiring from an emergency source or emergency source distribution overcurrent protective device to emergency loads shall be kept entirely independent of all other wiring and equipment except where otherwise permitted in 700.10(B) through (D).”

Interpretation:
This requirement ensures emergency circuits are functionally and physically independent from other systems to maintain reliability. However, it does not prohibit proximity when circuits are installed in separate, listed wiring methods, such as Type TC-ER cable, each with its own insulation, conductors, and jacket.

There is no NEC requirement that prohibits two distinct wiring methods — one for emergency and one for non-emergency — from being mechanically supported by the same cable tray, as long as they do not share conductors, enclosures, or raceways.

✅ 2. Cable Tray as a Support System – NEC 392.10(A) and Table 392.10(A)

“Cable trays shall be permitted to be used to support the wiring methods specified in Table 392.10(A) and as permitted in 392.10(B) through (J).”

Table 392.10(A) lists Type TC-ER cable as an acceptable wiring method for installation in cable trays, subject to the installation rules of its article — in this case, Article 336.

There is no restriction in Article 392 that prohibits a cable tray from supporting cables that serve different systems (e.g., emergency vs. non-emergency), as long as each wiring method is installed per its respective article and maintains system integrity.

✅ 3. TC-ER Cables as Independent Wiring Methods – NEC 336.10(7)

“Type TC-ER cable shall be permitted to be installed in cable tray and shall be permitted to extend for a distance not exceeding 1.8 m (6 ft) from the cable tray to a motor or fixed utilization equipment…”

Interpretation:
Each TC-ER cable is a complete wiring method — UL listed for use in cable trays — with individual conductors enclosed in a protective jacket. Emergency and non-emergency circuits routed in separate TC-ER cables retain the physical and functional independence required by NEC 700.10(A).

✅ 4. Precedent for Adjacent Wiring Methods

The NEC allows MC or TC-ER cables for emergency and non-emergency loads to be installed in parallel on walls, supports, or structural components, as long as they remain in separate wiring methods. Supporting them in a common cable tray does not change their classification, nor does it cause them to violate independence requirements.

Conclusion:

Installing emergency and non-emergency TC-ER cables in the same cable tray is code-compliant under the 2023 NEC, provided that:

• Each cable is a separately listed wiring method (TC-ER),

• Cables are not bundled, spliced, or sharing raceways or enclosures,

• The installation complies with 336.10(7) and 392.10(A), and

• The system is not in a location governed by NEC 700.10(D).

This approach maintains the physical and operational independence of the emergency system as required by NEC 700.10(A).