Section 552.56 of the 2017 National Electrical Code (NEC) provides the requirements for equipment grounding inside park trailers. Before reading it, review the definitions of bonding and grounding in Art. 100 to avoid confusion and errors.
What’s meant by “grounding” here is bonding. Grounding is a connection to the dirt; that’s not what you’re doing inside park trailers. In fact, this section begins by requiring all exposed parts in the electrical system be bonded [Sec. 552.56(A)] to the grounding terminals or enclosure of the panelboard.
The ground (dirt connection) is already established, you’re just bonding (providing a low impedance path) to where that system meets the supply. Electricity is trying to get back to its source, not to the dirt.
Don’t connect the neutral to the equipment grounding conductor; keep the two insulated from each other [Sec. 552.55(C)]. That goes for any connected appliances, too.
Always ensure that removal of a receptacle or other device does not interfere with the continuity of the equipment grounding conductor [Sec. 552.55(D)]. You can do this by pig tailing to the device.