Galvanic Isolators

What Is a Galvanic Isolator and Why Do You Need One?

If your boat or RV is plugged into shore power, you may be exposing its underwater metals — props, shafts, through-hulls, and trim tabs — to a silent but damaging threat: galvanic corrosion. A galvanic isolator is a critical piece of electrical safety equipment that blocks low-voltage DC currents from traveling through the AC shore power ground wire between your vessel and the marina's electrical system, while still maintaining a safe AC safety ground connection.

When multiple boats share the same shore power pedestal, differences in metal composition create a natural battery-like effect. Stray DC currents flow along the path of least resistance — often right through your boat's underwater hardware — accelerating corrosion far beyond what normal seawater exposure would cause. A properly rated galvanic isolator interrupts this current flow using blocking diodes, effectively decoupling your boat from the galvanic activity of neighboring vessels without compromising electrical safety.

How Galvanic Isolators Work

Galvanic isolators are wired in series with the AC shore power ground conductor. Inside, a set of diodes blocks low-voltage DC current (typically below 1.4V) from passing through, while allowing the full fault current capacity required by ABYC and NFPA standards to flow freely in the event of a true electrical fault. This dual function — blocking galvanic current while preserving shock protection — makes the galvanic isolator an essential, not optional, piece of equipment for any boat that regularly connects to shore power.

Sizing matters: galvanic isolators are rated by amperage, and you should always select a unit rated equal to or greater than your shore power connection (e.g., 30A or 50A). Failing to do so can compromise both the device and your safety ground integrity.

Galvanic Isolators for RVs

While the threat is most commonly associated with boats in a marina, RVs connected to campground shore power can face similar issues, particularly when metal chassis grounds interact with other vehicles at the same hookup. A galvanic isolator provides the same protective function, making it a worthwhile upgrade for full-time RVers and those who frequently use shared electrical pedestals.

Top Brands in Galvanic Isolators

NewMar is a respected name in marine electrical power management, and their galvanic isolators reflect the same commitment to quality and compliance. NewMar products are built to meet ABYC standards and are a trusted choice for boaters who demand reliable, long-term corrosion protection.

Pro Mariner brings decades of marine electrical expertise to their isolator lineup. Known for their robust battery charging systems, Pro Mariner applies the same engineering rigor to galvanic protection, making their isolators a dependable option for a wide range of vessel sizes and shore power configurations.

Quicksilver is a well-established marine brand with a broad catalog of boat parts and accessories. Their galvanic isolators are designed with the practical boater in mind, offering straightforward installation and reliable performance for protecting your investment against corrosion.

What to Look for When Shopping

• Amperage rating: Match or exceed your shore power circuit (30A or 50A)
• ABYC compliance: Ensure the unit meets current safety standards for marine electrical installations
• Fail-safe design: Look for units that default to a closed (grounded) state if the diodes fail
• Enclosure rating: A marine-grade weatherproof housing is essential for bilge or cockpit installations
• Easy installation: In-line wiring designs simplify retrofitting into existing shore power setups

Don't let galvanic corrosion quietly eat away at your boat's underwater hardware. A quality galvanic isolator is one of the most cost-effective ways to protect your vessel for years to come.