Article 545 Manufactured Buildings and Relocatable Structures.
Code Change Summary: Article 545 has been expanded to include relocatable structures.
For years, the requirements for relocatable structures such as mobile construction offices, clinics and the like have been located in Article 550 which is titled “Mobile Homes, Manufactured Homes, and Mobile Home Parks”, keyword being “homes”. A mobile relocatable structure is NOT a home and does not contain all the provisions required to consider it a home.
When searching the 2017 NEC® for language addressing relocatable structures, the following section in Article 550 was used to provide insight:
550.4 General Requirements.
(A) Mobile Home Not Intended as a Dwelling Unit. A mobile home not intended as a dwelling unit — for example, those equipped for sleeping purposes only, contractor’s on-site offices, construction job dormitories, mobile studio dressing rooms, banks, clinics, mobile stores, or intended for the display or demonstration of merchandise or machinery — shall not be required to meet the provisions of this article pertaining to the number or capacity of circuits required. It shall, however, meet all other applicable requirements of this article if provided with an electrical installation intended to be energized from a 120-volt or 120/240-volt ac power supply system. Where different voltage is required by either design or available power supply system, adjustment shall be made in accordance with other articles and sections for the voltage used.
In the 2020 NEC®, the title of Article 545 has been expanded to include both manufactured buildings AND relocatable structures. Additionally, a new Part II was added in Article 545 to address specific requirements for relocatable structures.
Now Article 550 only pertains to mobile homes, manufactured homes, and mobile home parks and offers no language or requirements on relocatable structures that are not a “home”.
Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC® edition of NFPA 70.
2017 Code Language:
ARTICLE 545 Manufactured Buildings.
2020 Code Language:
ARTICLE 545 Manufactured Buildings and Relocatable Structures.
545.1 Scope. This article covers requirements for manufactured buildings, building components, relocatable structures, and the conductors that connect relocatable structures to a supply of electricity.
545.2 Definitions.
N Relocatable Structure. 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 other than a dwelling unit without a permanent foundation.
Informational Note: Examples of relocatable structures are those units that are equipped for sleeping purposes only, contractor’s and other on-site offices, construction job dormitories, studio dressing rooms, banks, clinics, stores, shower facilities and restrooms, training centers, or for the display or demonstration of merchandise or machines.
N Part II. Relocatable Structures
N 545.20 Application Provisions. Relocatable structures shall comply with Part II of this article and the applicable sections of Part I.
N 545.22 Power Supply.
(A) Feeder. The feeder shall include four insulated color-coded conductors, one of which shall be an equipment grounding conductor. The equipment grounding conductor shall be permitted to be uninsulated if part of a listed cable assembly.