The present Federal Manufactured Home Construction Standards will permit the manufacturer of a manufactured home to install the electrical service equipment on the home. Section 550-23(a), Exception No. 2, of the 1996 National Electrical Code has a similar provision.
Whether the service is installed at the factory or in the field will obviously not affect the safety of the installation as long as the work complies with the National Electrical Code (NEC). This matter has been discussed with Mr. John Stevens of the HUD Manufactured Housing Standards Division, who advised that the federal regulation is not intended to prohibit the field installation of service equipment on a manufactured home.
In view of the above, pursuant to NEC Section 90-4, service equipment will be permitted to be field installed on a manufactured home under the following conditions:
1. The service installation must comply with NEC Article 230.
2. The manufactured home must be installed on a permanent foundation. The running gear is not required to be removed, as that would conflict with the HUD standard. A permanent foundation will be considered to be one consisting of piers or footings extending below the frost line or a floating concrete slab. Concrete block supports must have mortared joints.
3. The unit must be located on property owned by the manufactured home owner, and not on a leased or rented lot in a mobile home park.
Note the difference between manufactured buildings and mobile homes / manufactured homes.
Manufactured buildings (Article 545) are not built on a permanent chassis, as manufactured homes and mobile homes are, and by definition do not include manufactured homes or mobile homes.