Back-up Portable Generator grounding requirements for residential applications

[JELECT.]

What are the grounding, bonding, and grounding electrode NEC requirements, regarding the use of a portable generator used for back-up power to a residential home? this generator would be plugged into a 30 amp 125/250 volt 4 wire male inlet which connects to the main panelboard through a manually operated 30 amp, 2-pole circuit breaker that can only be closed by opening the main 100 amp service breaker which is mechanically interlocked with 30 amp breaker?

 

[tom baker]

That’s a lot to ask, it’s in Art 250 under generators, and article 702.
Is the generator solidly bonded or a floating neutral?

 

[don_resqcapt19]

To be code compliant you cannot have a neutral to frame bond at the generator. You don't need to anything else.

 

[LarryFine]

To be code compliant you cannot have a neutral to frame bond at the generator. You don't need to anything else.

Would there be a compliant way to use a 3-wire feeder from the genny, with the neutral doing grounding duties like a service?

 

[Sahib]

Would there be a compliant way to use a 3-wire feeder from the genny, with the neutral doing grounding duties like a service?

By using 4 pole transfer switch?

 

[suemarkp]

Actually a 3 pole transfer switch for most residences since they are single phase. The requirement is to switch the ungrounded and neutral conductors on a bonded generator, and use a 3 wire feed. It may need a GEC too. For an unbonded generator, you don't switch the neutral and use a 4 wire feed.

 

[LarryFine]

By using 4 pole transfer switch?

Two pole. Continuous, unswitched neutral. No separate EGC. Like a utility service.

 

[don_resqcapt19]

Two pole. Continuous, unswitched neutral. No separate EGC. Like a utility service.

Not permitted by the code unless there is no neutral to frame bond at the generator.

 

[tom baker]

Please review section 702.7
The generator type, unbonded or bonded neutral, is matched to the type of transfer switch. Most generators are bonded neutral type. On a generator with gfci for its outlets, when used with a transfer switch that does not transfer the neutral, the gfci will trip.