Issue

Certain portable generators with a GFCI outlet always trip when used with a transfer switch. 

Environment

This article applies to contractor-grade portable generators with a GFCI outlet when used with a transfer switch.

Cause

Certain portable generators designed for job site use must comply with OSHA regulations, which mandate GFCI protection on all receptacles. To meet OSHA inspection requirements, these "contractor grade" generators are also equipped with a bonded neutral wire connected to the ground wire. This setup creates a loop in conjunction with the bonded neutral in a home's main panel, causing a small induced current when the generator is running. The GFCI, which includes a ground fault sensor, detects this induced current and triggers the main circuit breaker in the generator.
 

Mitigation

When utilizing these bonded neutral generators, which also have full panel GFCI protection, to power a house or building through a transfer switch, a switch neutral kit can be employed for 30-amp transfer switches and generators.

If a switch neutral kit is unavailable or if the generator has a 50-amp receptacle, such as the XP10000E, an authorized service dealer must eliminate the bond between the neutral and ground.
 

Important considerations

• This modification renders the generator non-compliant with OSHA regulations for jobsite use (assuming it was compliant previously.)
• The dealer will affix an updated decal to notify users of the change. To determine if the neutral bond can be removed, it is recommended to contact a local dealer. It is advisable to have a dealer perform this task.
• Once the modification is complete, no adjustments to the transfer switch installation are necessary.
• Portable generators used with HomeLink manual transfer switches do not require the removal of the neutral and ground bond.