Paul, this is all i've found......
Art 550, Mobile Homes, Manufactured Homes, and Mobile Home Parks.
550.17 Testing.
(A) Dielectric Strength Test. The wiring of each mobile home shall be subjected to a 1-minute, 900-volt, dielectric strength test (with all switches closed) between live parts (including neutral) and the mobile home ground. Alternatively, the test shall be permitted to be performed at 1080 volts for 1 second. This test shall be performed after branch circuits are complete and after luminaires (fixtures) or appliances are installed.
Exception: Listed luminaires (fixtures) or appliances shall not be required to withstand the dielectric strength test.
(B) Continuity and Operational Tests and Polarity Checks. Each mobile home shall be subjected to all of the following:
(1) An electrical continuity test to ensure that all exposed electrically conductive parts are properly bonded
(2) An electrical operational test to demonstrate that all equipment, except water heaters and electric furnaces, is connected and in working order
(3) Electrical polarity checks of permanently wired equipment and receptacle outlets to determine that connections have been properly made
