The Victron galvanic isolator is a small, sealed box that protects your boat’s underwater metal from electrolytic corrosion. When you plug into shore power, the shore earth wire connects your boat to every other boat on the dock. Low-voltage DC currents can flow along that wire and eat away at your hull, propeller and shaft. The galvanic isolator blocks them while keeping the safety earth working.
How the Victron Galvanic Isolator Works
Victron explains that it contains two diodes connected in anti-parallel. Together they pass current in both directions, but only above a threshold of about 1.4 Vdc.
- Galvanic currents come from the voltage difference between metals. That’s lower than 1.4V, so the diodes block them.
- A real AC fault pushes a much higher voltage. The diodes conduct, and the residual-current device breaks the circuit.
So you keep earth-fault protection without the corrosion path. Victron says to install it directly behind the boat’s shore power connection.
Victron Galvanic Isolator: Specs
| Model | Max current | Peak current (20 ms) | Weight | Size (H x W x D) |
|---|---|---|---|---|
| 16A | 16A | 1,600A | 1 kg | 60 x 120 x 200 mm |
| 32A | 32A | 3,200A | 2 kg | 63 x 164 x 200 mm |
| 64A | 64A | 6,400A | 3.2 kg | 63 x 164 x 335 mm |
Source: Victron galvanic isolator product page specifications.
All models use M6 bolt connections in an anodized aluminium IP67 housing.
Galvanic Isolator vs Isolation Transformer
| Galvanic isolator | Isolation transformer | |
|---|---|---|
| Blocks galvanic DC currents | Yes | Yes |
| Full isolation from shore | No | Yes |
| Voltage conversion | No | Yes (some models) |
| Weight | 1-3.2 kg | 12-28 kg |
Victron’s isolation transformer datasheet says the transformer eliminates the need for a galvanic isolator. The isolator is the lighter, cheaper option when you only need corrosion protection.
Sizing
Match the isolator to your shore power inlet. A 16A inlet takes the 16A model, a 32A inlet takes the 32A, and larger boats use the 64A. The peak rating is there so the diodes survive a fault until the breaker trips.
Who It’s For
- Any boat that plugs into shore power and doesn’t have an isolation transformer.
- Boats in busy marinas, where stray currents are more common.
Good to Know Before You Buy
- No voltage conversion.
- Not full isolation. It blocks only low DC voltages.
- Has to be sized to your shore inlet.
Want the source figures? The galvanic isolator page on Victron’s site has the datasheet.
Where It Goes in the Wiring
The isolator is wired in series with the green or green/yellow earth (ground) wire only, not the live or neutral.
- Shore cable arrives at the boat’s inlet.
- The inlet’s earth conductor goes to one terminal of the isolator.
- The other isolator terminal connects to the boat’s AC earth bus.
- Live and neutral go to the main AC breaker as normal.
Victron says to install it directly behind the shore power connection, so no other earth path bypasses it. Any second connection from the shore earth to the boat’s earth would defeat it.
Worked Example: Matching a Model to Common Inlets
| Shore inlet | Model |
|---|---|
| 16A at 230V (European marinas) | 16A |
| 30A at 120V (US marinas) | 32A |
| 32A at 230V | 32A |
| 50A at 120/240V | 64A |
| 63A at 230V | 64A |
The isolator’s current rating should be at least the inlet’s breaker rating, so it can carry a full fault current until the breaker trips.
Worked Example: Why 1.4V Is Enough
Galvanic voltages between common boat metals are typically well under 1V. For example, the voltage difference between a bronze through-hull and an aluminium sterndrive is a fraction of a volt. Those small voltages can’t push current through the isolator’s anti-parallel diodes, which need about 1.4V to conduct. A real fault from a damaged appliance pushes tens or hundreds of volts, so the diodes conduct immediately and the protective device trips (illustration based on Victron’s 1.4V threshold).
Signs It’s Working
- Your zinc or aluminium anodes wear at a steady, predictable rate rather than disappearing quickly after a few weeks in a marina.
- A marine electrician can measure hull potential with a reference electrode with and without shore power connected; little change suggests the isolator is blocking stray currents.
Installation Steps
- Turn off and disconnect shore power.
- Mount the isolator close to the inlet on a solid surface; the IP67 aluminium case handles damp lockers.
- Cut the earth wire between the inlet and the boat’s earth bus and connect each end to an M6 terminal, using ring terminals and the correct torque.
- Check that no other wire connects shore earth to the boat’s earth.
- Restore power and have the system checked by a marine electrician.
Anodes Still Matter
A galvanic isolator stops stray current arriving through the shore cable, but it doesn’t replace your boat’s own sacrificial anodes. Those still protect against galvanic action between different metals on your own hull. Inspect and replace anodes on your normal schedule.
Choosing Between an Isolator and a Transformer
For a small to mid-size boat on a home marina berth, the isolator is the light, affordable way to protect underwater metal. Boats that travel between 120V and 230V marinas, or owners who want complete separation from shore, can step up to a Victron isolation transformer.
FAQ
What does a Victron galvanic isolator do?
It blocks low-voltage DC currents coming in through the shore power earth wire, which cause corrosion of underwater metals.
Where do I install it?
Directly behind the boat’s shore power connection, according to Victron.
Is it waterproof?
The housing is rated IP67.
Does the isolator affect my RCD or GFCI?
No. A real fault still flows through the diodes and trips the residual-current device as designed.
Do I need one on a boat without shore power?
No. It only matters when the boat connects to a shore earth.
Will it make my anodes last longer?
In a marina with stray currents, blocking the shore earth path usually slows anode wear, since the anodes are no longer protecting neighbouring boats as well as your own.
Sources: Victron galvanic isolator product page; Datasheet Isolation Transformers, victronenergy.com, accessed Oct 2026.
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