Shore power plugs outside North America

Types of travel adaptors plugs and outlets.

Harry Hungate

North American vessels arriving at foreign ports will find that their shore power cords and connectors are not compatible with those of other countries. Almost all other cruising destinations offer 220-volt AC single phase power at 50 hertz and either 10-, 16-, 32- or 64-amp service. A step-down transformer, either portable or permanently mounted, and a suitable power cord will be needed to bring shore power aboard your typical North American 120-volt AC 60-Hz equipped vessel. If you are confident in undertaking simple electrical projects, such as removing and installing power plugs and sockets, this article will provide a guide to correctly wiring the connectors. If you have not done any previous electrical work, please don’t attempt the following without competent assistance, as 220-volt AC power is most unforgiving.

Let’s start by reviewing the familiar and then progress to the new. Most vessels from North America are equipped for 120-volt AC 60-Hz single phase power at 30 amps. Larger vessels usually have 50-amp service. The yellow power cord connectors pictured in the accompanying photo are 30-amp female connectors that I have marked to show the location of each conductor. There are three color-coded conductors in the power cable: black is hot or active or line, white is neutral (there is no such thing as positive and negative in AC service), and green (or green with a yellow stripe) is ground or earth. Look closely at the photo and you will see that neutral is the smallest of the three terminals and earth is shaped like a curved “L.” Household-type 20-amp plugs and sockets are not waterproof and thus are not suitable for bringing aboard shore power. They should be used only for temporary connections such as for power tools.

Different color codes
Usual electrical service in marinas abroad is 220-volt AC single phase power at 50 Hz and 10-, 16-, 32- or 64-amp service. The 16- and 32-amp power cord plugs are the blue ones shown in the photo. Again, there are three conductors, but the color codes are different. Brown is hot or active or line, blue is neutral, and green (or green with a yellow stripe) is ground or earth. (Note: the old electrical service color code is red for active, black for neutral, and green for earth, and there is still a lot of the old wiring in use). The 64-amp connectors used for larger vessels look like a larger version of the 16- and 32-amp connectors and are wired identically. The ground connector is the largest of the three.

Most marinas will provide or rent an adaptor or plug to connect your power cable to their 10-, 16-, 32- or 64-amp outlets, but it’s a good idea to have your own aboard. They are simple to make and the cost is quite reasonable, especially if you have to pay daily rent on the connector.

Your next decision will be to purchase a new power cord or to modify your existing one. If you purchase a portable step-down transformer, then it makes sense to get a new power cord also, as it can be wired directly into the transformer, eliminating the need for a female connector. If you install a permanently-mounted transformer, you probably will want to wire it into your existing shore power connector on your vessel and continue to use your old power cable.

Think about this carefully, as the plug on the usual Marinco power cable is molded on and will have to be cut off — an irreversible step. With almost double the voltage (and consequently about half of the amps) the new power cable can be smaller than the old 120-volt power cable. For example, your old 30-amp power cable can be replaced with a cable having 14 AWG or 2.5 mm conductors. It may work out to be much cheaper to purchase a new cord and connectors, and the smaller diameter cable will most certainly be easier to handle and store than the standard Marinco 30-amp or 50-amp power cord. Whatever you decide, the connections are straight-forward. Keep a copy in your maintenance logbook for future reference. Remember: connect active to active, neutral to neutral, and earth to earth. Take the utmost care not to cross any of the conductors. Here’s another useful tip: When making any wire connection, give the exposed conductors a light coating of electronic-grade silicone grease. The silicone grease will exclude salt-laden moisture and prevent corrosion of the current-carrying copper. An excellent product to use is Senson Electroguard Grease (

Check for continuity
After installing the connectors and before applying power, use your digital multi-meter to check for continuity and short circuits in each conductor. It’s also a very good idea to acquire a plug-in type circuit checker which will indicate problems such as open earth circuit, open neutral, open active, reversed active and ground conductors, or reversed active and neutral conductors. Use this device each time a wiring change or connection to shore power is made. They are very inexpensive and may save your zincs or even your life.

If you plan to install some 220-volt AC outlets in your vessel, these vary from country to country. These should always be protected with circuit breakers or fuses.

A vessel connecting to shore power in New Zealand must have a “warrant of electrical fitness” which can only be issued after inspection by a certified electrical inspector. A drawing of your vessel’s electrical system showing main and branch circuit breakers, wire sizes, residual current detectors, transformers and outlets will be of great help to the inspector. Make one up now to prompt your memory later!

A word about frequency (which is measured in cycles per second or hertz): Most electrical and electronic devices today are designed to operate satisfactorily on either 60-Hz or 50-Hz electrical power. If in doubt, check the owner’s manual or contact the manufacturer. Induction and synchronous motors are frequency sensitive, meaning that electric clocks will run slow on 50 Hz, and pumps and compressors will operate at reduced capacity (assuming that they were designed to operate on 60 Hz), and may have a tendency to overheat.

If you don’t already have one or more aboard, now is the time to install a ground fault circuit interrupter (GFCI), also known as a residual current device (RCD). A combined circuit breaker (two pole) and RCD is available. This device will contribute greatly to the safety of your onboard electrical system.

Finally, start collecting the various adaptors that you will find necessary to connect your various electrical appliances.

Harry Hungate and his wife, Jane Lothrop, have cruised more than 45,000 miles aboard their Corbin 39 cutter, Cormorant, since moving aboard in Annapolis, Md., in 1997.

More articles by Harry Hungate:
Upgrading Yanmar oil pressure gauge and sender

Diesel fuel lift pump rebuild

Cool your alternator

Voyaging communications report: Cormorant

By Ocean Navigator