OSHA
Compliance
Portable Generator Safety and Regulations for Job Site Applications
1926.404 Wiring Design and Protection
The regulation requirements listed by OSHA in section 1926.404 refer specifically to operation on construction job sites. The importance of these regulations are to prevent the major cause for injury and fatalities when working with generators: shocks and electrocution from improper use and/or connections.
In summary, these regulations cover the importance of full panel GFCI coverage, and neutral conductors bonding to the generator frame, which acts in place of a grounding electrode system (i.e. driven ground rod).
Paying close attention to the operation methods listed in your portable generator’s user manual will assist preventing injuries if followed correctly. It is highly recommended that users seek consultation with their portable generator’s service team for clarification before installing job site appliances to ensure compatibility between the generator and the required load.
Ground-Fault Circuit Interrupter
Part 1926.404(b)(1)(ii) indicates that all 120-volt, single-phase, 15 and 20 ampere receptacle outlets on construction sites (not including the permanent wiring of the structure), need to have approved ground-fault circuit interrupters (GFCI) for personal protection against electrocution.
Furthermore, this same section specifies that receptacles on a portable or vehicle mounted generator under 5kW (5000 watts) does not need built-in GFCI if the circuit conductors of the generator are insulated from the frame and any other grounded surfaces.
If your portable generator is above 5kW, clarification of built in GFCI should be labeled clearly on the generator’s control panel. It is recommended that you do not attempt to install GFCI yourself if the generator does not come equipped with built-in GFCI.
Grounding
Part 1926.404(f)(3) specifies grounding conditions and requirements for portable and vehicle mounted generators. By definition, a portable generator is considered a separately derived system, meaning it is an electrical source having no direct connection to circuit conductors of any other electrical source.* (see source reference)
The portable generator frame may serve as the ground path for the system it supplies. In order for this to be true, all noncurrent-carrying metal parts of the generator need to be bonded to the generator frame. Likewise, the neutral conductor must be bonded to the generator frame as well.
The same requirements apply for vehicle-mounted generators as well, the only difference being that the generator frame must be bonded to the vehicle frame.
References:
US Department of labor
1926.404 Wiring and Design Protection
(b)(1) Ground-Fault Protection
(f)(3) Portable and Vehicle-Mounted Generators
Electrical License Renewal
Article 100 Definitions. Separately Derived System
http://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=7.0