How to Ground a Generator: When You Need a Ground Rod

Whether you need to ground a portable generator depends on how you use it. Under OSHA's rule, a portable generator's frame does not need to be grounded to a ground rod when it only powers equipment plugged into its own outlets and those outlets are bonded to the frame. If the generator powers a house through a transfer switch, it must be connected to a grounding electrode system, which is usually the home's existing ground. DuroMax's FAQ says a ground rod is "Not normally" needed for home backup power, but that local codes vary.

This article is general information. Grounding and bonding rules vary by location, so have a licensed electrician check your setup.

When a generator does not need a ground rod

OSHA's construction standard, 29 CFR 1926.404(f)(3)(i), says the frame of a portable generator need not be grounded, and may serve as the grounding electrode, when both of these are true:

• The generator supplies only equipment mounted on it, or cord-and-plug equipment through receptacles mounted on the generator, and
• The metal parts of that equipment and the grounding terminals of the receptacles are bonded to the generator frame.

OSHA's grounding fact sheet explains that in this case the generator's frame replaces the grounding electrode. A summary of the 2023 National Electrical Code (Section 250.34) describes the same idea. For most people running extension cords from the generator's outlets to appliances, that is the situation.

When it does need a grounding electrode

• Powering a house through a transfer switch. OSHA's fact sheet says a portable generator connected to a structure through a transfer switch must be connected to a grounding electrode system, such as a driven ground rod. In a home, that is typically the house's own grounding system, reached through the transfer switch and panel.
• When the conditions above are not met. OSHA says a grounding electrode, such as a ground rod, is required.

The NEC covers grounding of generators connected through transfer switches in Article 250. The transfer switch must be approved for the use and installed by a qualified electrician, per OSHA.

Bonded vs floating neutral

This is the part most people miss. DuroMax says all of its generators ship with a bonded neutral. If you use a 2-pole transfer switch for home backup, which does not switch the neutral, DuroMax says the generator must be unbonded to create a floating neutral. A 3-pole transfer switch, which switches the neutral, needs no change. DuroMax publishes model-specific instructions for removing the bond. Ask your electrician which type of switch you have before you connect.

How to ground a generator with a ground rod (DuroMax steps)

If your local code or situation calls for a ground rod, the DuroMax manuals describe it this way:

1. Find the grounding nut on the generator frame.
2. Use a grounding wire. DuroMax says a generally acceptable wire is No. 12 AWG stranded copper.
3. Tighten the grounding nut against the wire.
4. Connect the other end to a copper or brass grounding rod driven into the earth.

DuroMax adds that if the generator is connected to a home, you can use the home's ground instead of a separate wire and rod. Its manuals also say to always ground the generator before use, which is stricter than OSHA's rule, and that grounding codes vary by location. When the two disagree, follow your local code and your electrician.

Before driving a rod, call 811 so buried utility lines can be marked.

Grounding checklist

• Plugging appliances into the generator with cords? Usually no rod needed under OSHA's rule, if the outlets are bonded to the frame.
• Connecting to the house? Use a transfer switch or interlock kit, installed by an electrician, tied to the home's grounding system.
• Check bonded vs floating neutral against your transfer switch type.
• Keep grounding connections tight, as OSHA advises.
• Follow local code. It can require more than the federal rule.

Transfer equipment

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Compare options in Interlock Kit vs Transfer Switch and How to Hook Up a Generator to Your House. Browse transfer switches.

Questions about your setup? Call 1-888-855-7286. Tell us your generator model and how you plan to connect it, and we will point you to the right switch and DuroMax documents.

Generator grounding FAQ

Do I need to ground my portable generator? Not with a ground rod if it only powers cord-and-plug equipment from its own bonded outlets, under OSHA's rule. Local codes can require more.

Do I need a ground rod for a generator connected to my house? Usually not a separate one. OSHA requires a grounding electrode system, and DuroMax says you can use the home's ground when connected to the house.

What size wire do I use to ground a generator? DuroMax says No. 12 AWG stranded copper is generally acceptable.

What is a floating neutral? A generator whose neutral is not bonded to its frame. DuroMax says to unbond its generators for use with a 2-pole transfer switch.

Can I ground a generator to a water pipe? Ask an electrician. Grounding rules are set by the NEC and local code, and they vary.

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