ES - Marine Hull Isolation Transformers

ES Marine Hull Isolation Transformers    

Marine hull isolation transformers are the only way to completely eliminate the risk of galvanic corrosion between the ships hull and other metal objects (other ships, pilings etc.).

The problem is caused by an earth loop forming and current flowing through the earth wire on the shore supply. The problems occurs in all boats, although steel & aluminium boats are particularly susceptible. It is important to get advice from a suitably qualified marine surveyor or corrosion specialist before installing shorepower.

The isolation transformer eliminates any electrical continuity between shorepower and the ship. The shorepower is fed to the primary side of the transformer and the ship is connected to the output side (secondary).

The standard transformer range covers 16, 32, 50 & 63 amp shore capacities at 230v.

Hull Isolation Transformers

For more information or to request a quote please contact us.



ABYC Compliant. A metallic shield is fitted between the primary and secondary windings and is electrically isolated from all other portions of the transformer. It is fault tested at 4000 volts for 1 minute. This shield is wired via an insulated lead to the transformer chassis. The shield and its connection are able to carry the full load current of both the primary and secondary windings.

UL Compliant 

Although the transformer does not carry a full UL listing they are built to conform to the necessary standards.

Lloyds Compliant 

The transformer is built to conform to the Lloyds Resister standards.

European Cruising

An isolation transformer can also allow ‘English‘ wired boats to be used on continental shorepower supplies.

Most European countries have a floating neutral where the English system bonds the neutral to earth. This causes polarity problems abroad.

It also means that with single pole switches and circuit breakers there will always be voltage in through the neutral. The hull isolation transformer ‘converts‘ a floating neutral input into an earth bonded output.

The transformer will also ensure that the output polarity is always correct regardless of input polarity.


Standard Insulation

The standard transformer is protected by being immersed in a resin bath. This is done under a vacuum to ensure total coverage. This protects the transformer from air borne moisture and normal corrosion.

Double Dipped Insulation Option

In addition to the standard insulation the transformer receives a second water proof coating. The take off ends of the coil windings are also sealed to prevent water ingress. This additional insulation is suited to transformers that maybe subjected to water contact.

Soft Start

When first connected to the shore supply the hull isolation transformer will draw a very high initial current. This can often trip the shore supply circuit breaker. Energy Solutions are able to install a soft start on the input of the transformer to greatly reduce the inrush current.

Input Configuration

Most of the transformer range is offered with a dual wound primary. This allows the transformer to be connected to both 110 volt and 230 volt shore power supplies.

Output Configuration

The output configuration of the transformer can be user set to:

  • 230 volt for European systems
  • 240/120 volt for American systems    


Custom Transformers

Most of the Energy Solutions range of marine isolation transformers have dual input voltages (120 and 240 volt). This is of particular use on long distance cruising boats that may want to use 110 volt supplies in Caribbean, USA Etc.

They also help to protect swimmers against the risk of electrocution. This is a particular risk on fresh water moorings.

Safety for swimmers

Energy Solutions are able to supply specific transformers for individual applications. These may be single or three phase. We have supplied transformers up to 125 KVA.