Victron Isolation Transformers: Models and Specs

A Victron isolation transformer is one of the most important safety parts on a boat that plugs into shore power. Victron’s datasheet says it eliminates any electrical continuity between shore power and the boat. That protects against galvanic corrosion and makes faults on board trip a breaker instead of energizing the water. Here’s how it works and which model fits.

How a Victron Isolation Transformer Works

Shore power feeds the transformer’s primary side, and the boat connects to the secondary side. There’s no direct electrical path between the two. Victron explains:

The boat is isolated from shore ground. That blocks the stray DC currents that cause galvanic corrosion.
All metal parts connect to the secondary’s neutral output, so a GFCI trips or a fuse blows if there’s a short or a ground fault.
It replaces galvanic isolators and polarity alarms, according to Victron.

Victron Isolation Transformers: Specs

Model	Input / output	Rating	Weight
2500W	115 or 230V	22A / 11A	12.1 kg
4500W	115 or 230V	38A / 19A	22.2 kg
4500W Auto 115/230V	Auto-switching 115/230V	38A / 19A	21.8 kg
8000W	230V	35A	28.17 kg

Source: Victron Isolation Transformers datasheet (2500, 4500, 8000W).

Shared features: 50/60 Hz, toroidal winding for low noise and low weight, an input circuit breaker, soft start, aluminium IP21 enclosure, and the EN 60076 safety standard. Victron’s product page also lists 2000W, 3600W and 7000W versions, so check which models your dealer stocks.

Voltage Conversion

The 2500W and 4500W models can be wired four ways: 115V to 115V, 230V to 230V, 115V to 230V, or 230V to 115V. That’s useful for boats that cruise between US and European marinas.

The 4500W Auto switches automatically. A supply of 88-130V selects the 115V range, and 185-250V selects the 230V range.

Soft Start

Soft start is standard. Victron says it prevents the shore power breaker from tripping when you plug in, which can otherwise happen with large transformers.

Who It’s For

Boats on shore power, especially metal hulls or boats in crowded marinas.
Boats moving between 115V and 230V countries.
Anyone who wants better protection than a galvanic isolator gives.

Who Can Skip It

Boats that never plug in.
Small boats on a tight budget, where Victron’s galvanic isolator is the cheaper option for corrosion protection.

Good to Know Before You Buy

Heavy: 12-28 kg.
IP21, so mount it in a dry location.
Needs professional installation to meet marine code.

Victron’s isolation transformers product page has the full datasheet and manual downloads.

Worked Example: Matching a Model to Your Shore Inlet

Shore power inlets are rated in amps, so start there and compare with each model’s current rating from the datasheet.

Shore inlet	Power available (estimate)	Model that covers it
15A at 120V	≈ 1,800W	2500W (22A at 115V)
30A at 120V	≈ 3,600W	4500W (38A at 115V)
16A at 230V	≈ 3,700W	4500W (19A at 230V)
32A at 230V	≈ 7,400W	8000W (35A at 230V)
50A at 120/240V split-phase	Two 50A legs	Larger or multiple units; ask a marine electrician

Estimates: amps × volts. Pick a transformer whose rated current is at or above the inlet’s breaker. An undersized transformer will trip its own input breaker before the marina pedestal does.

Worked Example: Running a Boat Abroad

Say a US-built boat with 120V appliances is spending a season in a 230V Mediterranean marina. The marina offers 16A at 230V, about 3,700W. A 4500W transformer wired 230V-in to 115V-out turns that into about 32A at 115V (3,700 ÷ 115, estimate before losses). That’s enough for a 120V water heater and battery charger together, and it saves rewiring the boat.

Isolation Transformer vs Galvanic Isolator

	Isolation transformer	Galvanic isolator
How it works	No conductive path to shore at all	Diodes block low DC voltage on the ground wire
Corrosion protection	Full isolation from shore ground	Blocks small galvanic voltages
Polarity problems at the dock	Handled on board, since the secondary is local	Still needs a polarity indicator
Voltage conversion	2500W and 4500W models can convert 115V ↔ 230V	None
Size and weight	12–28kg	Small and light

Both are Victron products. The isolator is the budget route. The transformer goes further and also handles mixed-voltage marinas.

Where It Fits With Your Other Victron Gear

The transformer sits between the shore inlet and everything else. A MultiPlus or Quattro inverter/charger then takes its AC input from the transformer’s output. The inverter/charger’s own transfer switch and ground relay keep working as usual, with the transformer’s secondary acting as the local source.

Before You Buy: A Quick Checklist

Note your inlet’s rating and voltage (on the inlet plate).
Decide whether you’ll ever plug in at a marina with a different voltage. If so, pick a 2500W, 4500W or 4500W Auto.
Measure the mounting space. The 4500W weighs about 22kg and needs a dry location for its IP21 case.
Plan cable runs from the inlet to the transformer and from the transformer to the AC panel, sized from the manual.
Book a marine electrician to complete and check the install.

FAQ

Do I need a galvanic isolator with a Victron isolation transformer?

No. Victron says the isolation transformer eliminates the need for galvanic isolators and polarity alarms.

Can it convert 230V shore power to 115V?

Yes. The 2500W and 4500W models can step 230V down to 115V, and the reverse.

Will it trip the shore breaker?

Soft start is standard to prevent that.

Does the 4500W Auto boost low marina voltage?

The Auto model selects its range automatically and, per Victron’s manual, raises output slightly with a 1:1.05 ratio, which helps on long docks where voltage sags.

Is an isolation transformer noisy?

Victron uses a toroidal winding, which it notes is quieter and lighter than a conventional transformer.

Can I use it on a houseboat or floating home?

Yes. Any vessel that connects to shore power benefits from the same isolation.

Sources: Victron Isolation Transformers product page and Datasheet Isolation Transformers 2500, 4500, 8000, victronenergy.com, accessed Oct 2026.