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Article 550 generally includes manufactured homes in the term "mobile home" [550.2]. But in some cases, there's a distinction - and it's important. So how can you avoid confusion? If both terms appear in any subsection, the NEC is making a distinction; if only "mobile home" appears, then it's not.
These homes come in many sizes, including high square footage configurations (Photo 1). But the traditional trailer-sized unit (Photo 2) is (for economic reasons) perhaps the most popular. Unfortunately, the compact size of the "trailer" means flammable possessions form a high fuel density (relative to other home types), and there's less space around ignition sources - notably space heaters. Consequently, occupants of "trailer" homes are disproportionately represented in fire fatality statistics.
The NEC doesn't directly tackle the size issue. But it does mitigate other risk factors, which exist regardless of unit size. After presenting some general requirements, Art. 550 begins risk mitigation by addressing the power supply.
Structure power requirements
The power requirements could be confusing, because you find power requirements at the beginning of Part II in 550.10 and 550.11, but then Part III is titled "Services and Feeders." The "secret" here is the requirements of Part II are for supplying power to the individual unit while the requirements in Part III are for distributing power in mobile home parks (Photo 3) and the services to individual units.
The power supply to a mobile home must be a feeder assembly consisting of a listed 50A mobile home power supply cord or a permanently installed feeder 550.10(A). This requirement has two Exceptions. If the unit is:
1. Equipped with gas or oil-fired central heating equipment and cooking appliances. In that case, you can use a 40A supply cord.
2. Constructed per the seven conditions enumerated in 550.32(B). This is typically a larger "manufactured home" rather than a "trailer." The service size is often comparable to that of a typical site-built stick home.
If you do run the listed cord, you must permanently attach it to the panelboard and ensure the free end terminates in an attachment plug cap [550.10(B)]. The cap must be a 3-pole, 4-wire grounding type [550.10(B)]. The cord can't be...