GMIs in RVs: What Campground Owners Need to Know

David Cohen — Park Infrastructure & Technology Consultant

Let's look into the future. Picture this: Your campground is sold out for the July 4th weekend. A guest just checked in and tells your staff, “I have no power at my site.” Your staff moves him to another site — but he still has no power.

You ask, “Do you know if your RV is equipped with a GMI?” He gets even more frustrated. “I know it's not my camper! It's new! I have no power — fix it!”

Welcome to the classic no-win situation. Whether the GMI has malfunctioned or the campground has a grounding problem, the guest may still blame the campground. From his perspective, his new RV has no power — and it's happening at your park. He may never come back, and he may tell his friends about the terrible experience he had.

This is the not-so-fun side of GMIs that campground operators need to be prepared for.

If you haven't heard about the change, beginning in 2027, new Model Year 2028 RVs with 30-amp or 50-amp electrical service will begin entering the market with Grounding Monitor Interrupters (GMIs) installed in their electrical systems. The RV Industry Association has established January 1, 2027, as the effective date for the requirement, with mandatory enforcement beginning with each manufacturer's Model Year 2028 production. Because manufacturers will transition at different times, GMI-equipped RVs will enter the market throughout 2027.

While there have been press releases, industry updates, and plenty of discussion about the change, many park owners and operators are still unsure how this new requirement will affect their day-to-day operations.

For RV manufacturers, GMIs are a compliance requirement. For campground owners, they represent a new operational reality that may expose wiring problems, aging infrastructure, and maintenance gaps that older RVs have not necessarily revealed.

In simple terms, let's look at what GMIs do, how campground operators may need to adjust, and what we should all begin preparing for. Without getting too technical or reviewing every detail of the change, here are several key points based on real-world experience that park owners should keep in mind as GMIs begin entering the market.

What Does a GMI Do?

A GMI (Grounding Monitor Interrupter) is a safety device built into newer RVs. Its job is to verify that the RV has a proper equipment-grounding connection to the campground's electrical system before allowing AC power to enter the RV.

When an RV plugs into a pedestal:

• If the grounding connection is acceptable: The RV can receive pedestal power normally.
• If the grounding connection is missing or a loss of ground is detected: The GMI will prevent power from entering the RV or disconnect power if the problem occurs while the RV is operating.

The RV's 12-volt DC system is not normally affected by the GMI, so an RV may still have 12-volt power even when its AC shore power has been disconnected.

If you've ever touched an RV while standing on wet ground and felt a slight “tingle,” you've experienced a potential hot-skin condition — where an RV's metal exterior or frame can become energized because of an electrical fault or grounding problem.

A GMI is designed to help protect against this type of dangerous condition by monitoring the grounding connection and preventing or disconnecting AC power when a loss of ground is detected.

GMIs are intended to make RVs safer — and we all want our guests to be safe.

So, What’s the Problem?

Campground Consulting Group (CCG) visits hundreds of campgrounds each year, and routinely see pedestals that receive little or no preventive maintenance unless a guest reports a problem. In our discussions with pedestal manufacturers, detailed maintenance recommendations vary, and manufacturers generally recommend regular inspection and preventive maintenance — including cleaning out insects and debris, replacing worn or broken receptacles, checking and tightening lugs and terminals by qualified personnel, and periodically testing for proper wiring and grounding.

Before GMIs, a pedestal could have a marginal electrical connection and still deliver power to many RVs. With GMI-equipped RVs, a grounding problem can prevent the RV from receiving power at all.

The GMI relies on a proper equipment-grounding connection. Loose lugs, corroded terminals, worn or damaged receptacles, or other problems within a pedestal or electrical distribution system can contribute to grounding problems. If the GMI detects a loss of the required grounding condition, it will disconnect power to the RV.

Ignoring pedestal maintenance becomes much harder to get away with in a GMI world. As GMIs become more common, preventive maintenance becomes increasingly important.

What About Older Campgrounds?

NEC Article 551 addresses electrical requirements for recreational vehicles and recreational vehicle parks. The 1971 edition of the National Electrical Code was the first NEC edition to include specific electrical requirements for recreational vehicle parks, making 1971 an important historical reference point when evaluating older campground electrical systems.

Campgrounds built before 1971 may have electrical systems that predate those requirements but this does not automatically mean the electrical system is unsafe or needs to be completely rebuilt. However, older systems deserve particular attention because their original electrical infrastructure may have been installed before the NEC established specific requirements for RV parks.

You don't need to rebuild your entire park simply because GMIs are coming. You do need to know what you have and confirm that your electrical system provides a proper equipment-grounding path.

When Are GMIs Likely to Become an Operational Concern?

Industry data from RVIA, RVDA and SSI estimate approximately 8 million RVs in use in the U.S. with approximately 300,000 to 350,000 manufactured each year and an equivalent number sold by RV dealers each year. Most RVs use campground electrical hookups, with larger towable and motorized RVs using 30-amp or 50-amp service.

The GMI requirement takes effect January 1, 2027, with mandatory enforcement beginning with each manufacturer's Model Year 2028 production. Because manufacturers will transition to Model Year 2028 production at different times, GMI-equipped RVs will be phased into the market throughout 2027.

As a result, GMI-equipped RVs will represent only a small percentage of the overall RV population in 2027. Based on the gradual phase-in of the requirement and the existing RV population, and the number of new RVs sold each year, it is unlikely that GMI-equipped RVs will represent a significant percentage of campground guests until the mid-2030s and later. One problem is one too many but the timing is important because it gives campground operators time to evaluate their electrical infrastructure before GMI-equipped RVs become common.

Operators should use this transition period to inspect older wiring, grounding systems, and pedestal installations, and make repairs or upgrades where needed. Special attention should be paid to electrical systems installed before 1971.

If your campground's electrical infrastructure has never been thoroughly inspected — or if you are aware of existing grounding, wiring, or pedestal issues — now is the time to address them.

Campground pedestals and electrical distribution systems that are properly wired, grounded, and maintained today should be well positioned to serve GMI-equipped RVs tomorrow.

How Do You Test Your Campground Pedestals?

A good place to start is with a 3-light, standard 15/20-amp, 120-volt receptacle testers that many campgrounds already use. These simple plug-in testers can identify common wiring problems, including incorrect polarity, an open neutral, or an open ground at the receptacle.

50/30/20 RV pedestals typically include a 20-amp, 120-volt convenience receptacle, which is required to have GFCI protection under applicable NEC requirements. If the tester has a dedicated GFCI test button, it can also be used to verify that the GFCI trips properly.

The tester results are easy to read using a series of indicator lights that quickly show whether the receptacle is wired correctly or has a problem.

For campground pedestals, similar plug-in testers are available for 30-amp and 50-amp RV receptacles. These testers allow someone with limited electrical training to perform a useful first-level check and quickly identify common wiring problems at the pedestal.

This type of testing should be part of a campground's regular electrical inspection and preventive-maintenance program.

Be sure to use quality properly listed and tested equipment, such as products carrying a UL or ETL listing, appropriate for the type of receptacle being tested.

These plug-in testers are a first step. They do not verify the complete equipment-grounding path from the pedestal back to the electrical service. Additional testing should be performed to fully evaluate a campground's electrical system and grounding continuity.

Testing the Grounding Path

The more important test for GMI-equipped RVs is verifying the equipment-grounding path from the RV pedestal back to the electrical service equipment. This is different from simply confirming that a ground is present at the receptacle.

The goal is to verify the integrity and continuity of the grounding path through the pedestal, feeder, and distribution system back to the source. The RV Industry Association specifically recommends that RV parks and campgrounds test for good ground continuity from the site pedestals back to the electrical service panels as part of annual preventive maintenance.

Purpose-built 30-amp and 50-amp testing devices designed to evaluate the complete equipment-grounding path and GMI compatibility are not yet commercially available. Based on our discussions with manufacturers, testing solutions are being developed and are expected to become available before GMI-equipped RVs enter the market.

In the meantime, campground operators should work with a qualified electrical professional to evaluate the grounding continuity of their electrical system, particularly at older sites and installations. This is especially important for campgrounds with older electrical infrastructure, known grounding issues, or systems that have never been thoroughly evaluated.

How Reliable Are GMI Devices in New RVs?

It is not known how reliable the new GMIs will be in real-world RV service. They are new devices, and there is not yet a long-term track record showing how they will perform over many years of actual RV use.

My manufacturing background tells me to take a balanced approach: don't assume the GMI will be unreliable, but don't assume a first-generation device will have a 20-year track record either. These first-generation GMI devices are being designed, developed, and tested now, with manufacturing and release expected to begin as Model Year 2028 RV production gets underway in 2027.

As safety devices, GMIs are subject to applicable product testing and listing requirements. But from a reliability standpoint, two questions will ultimately matter:

Will the GMI protect the RV when it should? Will the GMI nuisance-trip when there isn't a dangerous condition?

RV electrical systems have become increasingly complex, with inverters, converters, battery chargers, variable-speed equipment, and other electronics. The RV environment can also be demanding on electronic components, with vibration, temperature extremes, moisture, and long periods of inactivity.

The real test will come with time and experience in the field. As these systems become more common, manufacturers, RV owners, and campground operators will gain a better understanding of how reliably GMIs perform under the wide range of conditions found in real-world RV use.

Prevention Strategies

If you have an older property, one option is to identify GMI-equipped RVs when guests make a reservation. Add a simple question to your online reservation process:

“Do you have a 2028 or newer RV?”

While this is not a solution by itself, knowing in advance which guests are arriving with newer, GMI-equipped RVs can help campground operators be proactive, identify potential electrical issues before the guest arrives, and be better prepared to troubleshoot a power problem if one occurs.

Another option is to let guests know that electrical safety and preventive maintenance are part of the campground's regular maintenance program. This can help build confidence and reassure guests that the park takes its electrical infrastructure seriously, without suggesting that every pedestal is guaranteed to be problem-free.

The goal is not to treat every GMI-equipped RV as a potential problem. The goal is to know when they are arriving, make sure your electrical infrastructure is properly maintained, and have a plan in place if a GMI-equipped RV does not receive power.

The Bottom Line

The arrival of GMI-equipped RVs does not mean campground owners need to panic or replace perfectly good pedestals. If your park is properly wired, grounded, and maintained, you are already in a good position for the GMI era. GMI-equipped RVs are designed to work with properly installed campground electrical systems and add another layer of safety for the RV and its occupants.

The parks most likely to experience problems are those with:

• Aging electrical infrastructure
• Loose, worn, or damaged receptacles
• Older or improperly grounded electrical systems
• Inconsistent electrical maintenance
• Known wiring or grounding problems that have not been addressed

The good news is that campground operators have time. Use the transition period to evaluate your electrical infrastructure, test your pedestals, verify the integrity of your grounding system, repair or replace worn components, and plan upgrades where they make sense. Pay particular attention to older electrical systems and sites that have had recurring electrical problems.

GMIs don't have to be a burden. They can be an opportunity. They give campground operators a reason to identify and correct electrical problems before they become guest complaints—and to make sure their parks are ready for the next generation of RVs.

The goal isn't to replace what doesn't need replacing. It's to know what you have, make sure it is safe and properly maintained, and be prepared for the future.

By Campground Consulting Group. Concerned about your park’s electrical infrastructure ahead of the GMI transition? Reach out for a complimentary consultation.