Understanding NEC Article 552: Park Trailers
NEC Article 552 outlines the electrical requirements for park trailers, which are semi-permanent living units designed for seasonal use. These structures, often found in campgrounds and RV parks, require safe and efficient electrical systems to accommodate both low-voltage and high-voltage needs.
Scope of Article 552
This article applies to:
- Park Trailers: Units with a single chassis and wheels, designed for seasonal use, not exceeding 400 square feet.
- Combination Systems: Electrical systems that include both 120/240-volt AC and low-voltage DC circuits.
Exclusions:
- Park trailers used for commercial purposes, which fall under Article 545.
- Permanent dwellings, which are governed by Article 550.
Key Requirements for Park Trailers
- Low-Voltage Systems
- Low-voltage circuits must use copper conductors.
- Battery installations must be ventilated to the exterior to prevent gas accumulation.
- Grounding connections must use secure methods, with conductors no smaller than 8 AWG.
- Combination Electrical Systems
- Voltage converters must separate AC and DC circuits to prevent interference.
- Dual-voltage fixtures must be listed and include barriers to segregate 120-volt and 12-volt wiring.
- 120/240-Volt Systems
- Wiring methods must comply with NEC standards for raceways and cables.
- Panelboards must have a grounded conductor insulated from the equipment grounding conductor.
- Branch Circuits and Receptacles
- Kitchens must have GFCI-protected receptacles at countertop areas.
- Outdoor receptacles must be weatherproof and GFCI-protected.
- No receptacles are allowed in or within 30 inches of shower or bathtub spaces.
- Cord and Power Supply
- A listed 30- or 50-ampere power-supply cord must be securely attached to the panelboard or junction box.
- Cords must not exceed a length of 36.5 feet and must include strain relief mechanisms.
Grounding and Bonding
- All exposed metal parts, including roofs and exterior coverings, must be bonded to the grounding terminal of the panelboard.
- Gas, water, and waste pipes must also be bonded to the chassis for safety.
Factory Tests
Each park trailer undergoes factory testing, including:
- Continuity Tests: To verify bonding of all metal parts.
- Polarity Checks: Ensuring proper wiring connections.
- Operational Tests: Confirming all equipment functions correctly.
Applications
NEC Article 552 ensures safe electrical systems in:
- Seasonal Housing: Campground and RV park units.
- Mobile Temporary Units: For recreational or semi-permanent living.
- Expandable Park Trailers: Units with additional compartments or features.
Conclusion
NEC Article 552 provides essential safety standards for park trailers, addressing the unique electrical needs of these seasonal dwellings. Proper grounding, wiring methods, and testing practices ensure safe operation and compliance in diverse environments.
