Grounding a portable generator

midijeep · August 2017

I have a grid-tied battery backup PV system. I am in the process of tying in my Ryobi portable generator into the system. I have a Eaton EGSX 100A Standard Automatic Transfer Switch, which will connect into a Midnite Solar E-Panel. I'll bring the grid AC line into the ATS as well as the generator output, then run the output of the ATS into the E-panel (currently the Grid AC goes directly into the E-Panel.

The Ryobi portable generator is neutral bonded. Do I need to ground the generator directly to a ground rod?

mike95490 · August 2017

What does the Generator Manual say ? Does the transfer switch, switch L1, L2, N, & G ?

midijeep · August 2017

mike95490 said:

What does the Generator Manual say ? Does the transfer switch, switch L1, L2, N, & G ?

I guess what I am asking is since the generator is neutral bonded does it need to be grounded with a grounding rod?

Manual for ATS states:

Step 1:

Connect cables as follows (see Figure 15, and

Table 2):

• The utility power cables to the utility lugs: or SE breaker if

installed;

• The generator power cables to the generator lugs.

• The customer load cables to the main distribution panel (load) lugs;

• The neutral cables to the neutral bar; and

• The ground wires to the ground bar.

Can I run a ground wire from the ground bar in the ATS to the E-Panels Ground bar?

Generator manual states:

GROUNDING THE GENERATOR

KEEP AT LEAST 20 FT. AWAY

Only use OUTSIDE and FAR AWAY from windows, doors, and vents.

CO Detector in Living Areas

If this generator will be used only with cord and plug-connected equipment, National Electric Code does not require that the unit be grounded. However, other methods of using the generator may require grounding to reduce the risk of shock or electrocution. Consult a qualified electrician, electrical inspector, or local agency

having jurisdiction for local codes or ordinances to find out if ground- ing is needed in your situation before using the generator.

When grounding is required, the nut and ground terminal on the frame are
used to connect the generator to a suitable ground source. The ground path should be made with #8 size wire. Connect the terminal of the ground wire between the lock washer and the nut, and tighten the nut fully. Connect the other end of the wire securely to a suitable ground source that is in contact with the soil for a minimum distance of 8 ft.

The National Electric Code contains several practical ways in which to establish a
good ground source. If a steel or iron rod is used, it should be at least 5/8 in. diameter, and if a nonferrous rod
is used, it should be at least 1/2 in. diameter and be listed as material for grounding. If a rock bottom is encountered before reaching a depth of 8 ft., drive the ground rod in at an angle of up to 45°. If the rock bottom is again encountered, the rod can be buried in a trench that is at least 30 in. deep. In all cases, the upper end of the grounding rod should either be flush with (or below) the ground or must be otherwise protected from physical damage.

All electrical tools and appliances operated from this generator must be properly grounded by use of a third wire or be “Double Insulated.”

It is recommended to:

Use electrical devices with 3-prong grounded plugs.
Use an extension cord intended for outdoor use with a 3-pole receptacle and a 3-prong plug at opposite ends to ensure continuity of the ground protection from the generator to the appliance.

Check and adhere to all applicable federal, state, and local regulations relating to grounding specifications. Consult a qualified electrician or service personnel if the grounding instructions are not completely understood or if in doubt as to whether the generator is properly grounded.

Estragon · August 2017

This gets complicated, but as a rule I would not ground a neutral bonded portable generator.

There should already be a ground to the house AC panel. If so, connecting the generator ground to the panel ground should effectively ground the generator chassis.

mcgivor · August 2017

Generally speaking, a portable generator has a neutral bond is satisfy safety requirements for portable use, the connection to a grounding point is required to reference the neutral to ground bond, without an established ground there would be no neutral.
When used to connect to a homes main panel via a transfer, it now becomes non portable, when connected, in this case the generators neutral bond is not required, to satisfy the single neutral bond point, which would now be in the panel. The single ground point requirement would now mean the generator would need to be bonded to the house ground, not a separate ground rod at the generator.

The grey area is, by removing the generator neutral bonding the unit is now technically not portable and by using an extention cord versus hard wire, you would be using it as a portable device. This would definitely be a question to ask an inspector with the authority having juristiction, doing something wrong could have serious safety implications and possibly void insurance coverage, should something go wrong.

midijeep · September 2017

I should mention that I will place a generator inlet box outside and run that to the ATS, then to Midnight Solar E-Panel.

mike95490 · September 2017

It all depends on what the inspector wants to see, and how the transfer switch operates

Grounding a portable generator

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