Residential portable generator bonding

[five.five-six]

Should the portable genset get it’s own ground rods or just bond to the existing GEC? Seems to me the point is to trip existing overcurrent and/or GFCI devices for safety.

 

[roger]

The GE does not have anything to do with tripping OCPD's.

 

[infinity]

Should the portable genset get it’s own ground rods or just bond to the existing GEC?

In most cases neither unless for some reason the portable generator is set up as a SDS. Most residential systems with a small generator, inlet, and interlock are set up as a non-SDS.

 

[five.five-six]

The GE does not have anything to do with tripping OCPD's.

It’s bonded to the EGC which it’s only purpose is to trip OCPD’s and GFCI’s

 

[five.five-six]

In most cases neither unless for some reason the portable generator is set up as a SDS. Most residential systems with a small generator, inlet, and interlock are set up as a non-SDS.

So just a 3 wire connection?

 

[infinity]

So just a 3 wire connection?

An SDS would be a 3-wire connection similar to a service. A non-SDS would be a 4-wire connection where the neutral and EGC within the generator are not bonded together. The SDS would require a connection to the building grounding electrode system (GES). The non-SDS would not require a connection to any electrodes or the building GES.

 

[kwired]

A portable generator with unbonded neutral:

If connected to premises wiring system will be bonded via the main/system bonding jumper of the premises wiring and the EGC back to the generator. Things are pretty much same as when not running on the generator when it comes to clearing ground faults.

If used stand alone for portable equipment plugged into it, it is an ungrounded system. When the first ground fault occurs it becomes a grounded system. When a ground fault occurs on another system conductor, high level current flows and opens overcurrent protection.

 

[roger]

So just a 3 wire connection?

As a non-separately derived system you would need four (includes an EGC)

 

[five.five-six]

As a non-separately derived system you would need four (includes an EGC)

View attachment 2575599

Exactly how I was planning on connecting it.

 

[infinity]

Exactly how I was planning on connecting it.

There are a few options. Non-SDS is IMO the best because it's the least amount of work for the same result. Whatever system you decide to install don't forget the required signage in Article 702.