There have been some major changes in the 2023 National Electrical Code dealing with mobile and manufactured home electrical services. Some involve relaxation on the location of the services while still observing safety issues such as not connecting service equipment directly on the mobile home. Locating the service within a reasonable distance from the mobile or manufactured home so first responders can easily access the main disconnecting means is certainly a concern.

Let’s look at these service requirements in detail. The first issue is the major difference between the definitions for a mobile home and a manufactured home in Article 100.

Mobile home requirements 

A mobile home is defined as follows: “A factory-assembled structure or structures transportable in one or more sections that are built on a permanent chassis and designed to be used as a dwelling without a permanent foundation where connected to the required utilities and that include the plumbing, heating, air-conditioning, and electrical systems contained therein.” 

Where the outside sheeting on the mobile home is aluminum or fiber cement that may be conductive, installing an electrical service on this sheeting could be dangerous since the neutral and equipment grounding conductor are connected by a main bonding jumper within the metal service enclosure. This connection could place the mobile home’s metal sheeting and support structure in direct contact with the neutral of the metal service enclosure since the neutral is a current-carrying conductor. 

If a similar mobile home with a conductive exterior is within close proximity, losing a neutral in one mobile home could involve a person touching both at the same time with neutral current going through the person. This was certainly a major concern in the past when the exterior of almost all mobile homes was constructed with conductive sheeting. The outside sheeting on a new mobile home could also be constructed of a conductive covering. 

For this reason, NEC 550.32(A) states, “the mobile home service equipment must not be mounted in or on the mobile home. The service equipment must be rated not less than that required in accordance with 550.32(C), be mounted in a readily accessible outdoor location, and be located within sight from the mobile home it serves.” 

Locating the service to the mobile home within sight of it requires compliance with NEC 110.29 as follows: “Where this Code specifies that one equipment shall be ‘in sight from,’ ‘within sight from,’ or ‘within sight of’ another equipment, the specified equipment shall be visible and not more than 50 feet distant from the other.” 

The 2023 NEC allows the service to be up to 50 feet away and within direct line-of-sight, relaxing the previous 30-foot limit set by the 2020 and earlier editions. 

In addition, the last sentence in NEC 550.32(A) permits the main disconnecting means for the electrical service to be the emergency disconnect as required in NEC 230.85 for all one- and two-family dwellings so first responders can easily shut the power down in an emergency. This disconnecting means will be clearly visible and easily accessible in an emergency.

Manufactured homes

A manufactured home is made differently  than a mobile home and is defined as follows: “A structure, transportable in one or more sections, which in the traveling mode is 8 feet or more in width or 40 feet or more in length, or when erected on site is 2,320 square feet or more is built on a permanent chassis and is designed to be used as a dwelling with or without a permanent foundation, whether or not connected to the utilities, and includes plumbing, heating, air conditioning, and electrical systems contained therein. The term includes any structure that meets all the requirements of this paragraph except the size requirements and with respect to which the manufacturer voluntarily files a certification required by the regulatory agency. Calculations used to determine the number of square meters (square feet) in a structure are based on the structure’s exterior dimensions and include all expandable rooms, cabinets, and other projections containing interior space, but do not include bay windows.” 

The electrical service can be located on or inside the manufactured home, complying with Article 230. The manufacturer must provide written installation instructions with the method of grounding the service at the installation site, the minimum size of the grounding electrode conductor and must comply with Article 250, parts I through V. A warning label must be mounted on or adjacent to the service equipment with the following: “WARNING: DO NOT PROVIDE ELECTRICAL POWER UNTIL THE GROUNDING ELECTRODE(S) IS INSTALLED AND CONNECTED. SEE INSTALLATION INSTRUCTIONS.” 

Follow the requirements for safe installation and use of electrical power for mobile and manufactured homes.

MALP / STOCK.ADOBE.COM