KNOWING YOUR MARINE ELECTRIC - 5 SEPTEMBER 2021

Had a dock walker ask a valid question today about Marine electric Dock power and hull connector plugs:

America is very far behind the rest of the world dock power-wise, it is embarrassing... very few harbors have 50 amp 240 volt service or 100 amp 240 volt service. America generally frowns on live-aboards, and intentionally limit courtesy services like WiFi and electric.

Here is a quick review,  

  • Less than 32ft (trailerable boats) usually outboard powered: one 15 amp (standard household style outlet), mostly for charging batteries or running lights, heater.

  • 33ft to 45ft boats: usually have a 30 amp 3 wire round marine outlet (for supplying two household type 120 volt dual receptacles) since Y2K most 40+ foot boats have the 50 amp system described below.

  • 45ft to 65ft boats: almost all have 50 amp 120 volt round RV/Marine style, 3 wire (hot+ground-neutral) plugs...or...a 50 amp 240 volt 4 wire (two 120 volt 50 amp hot+ground-neutral) plug yielding 100 amps of
    120 volt capacity.

  • Over 65ft boats: usually have a 100 amp 240 volt 4 wire plug, (two 120 volt 100 amp hot+ground-neutral)

*Remember, when looking at the plugs 50 amp service and above still only has three lugs (prongs) (the ground is in the periphery of the plug) ... very confusng ! Marinco and Hubbell marine plugs are different than RV plugs, many cross over but many do not.

In the Caribbean, Europe and UK things are very different !
Our electric power is 60 cycle, theirs is 50 cycle... and the plugs are many.  Almost everything is 240 volt.

The IEC 60309 3 pin round 230 volt "blue plug" has a standard size 16A version and a bigger 32A version, the smaller is more common you can also marry a 16 to a 32.

Yellow plugs are 110v, Blue plugs are 230 v, and Red plugs are 3 phase 440 all are 50 cycle...not 60 cycle.

The IEC 60309 system is available to buy in the US by Googling for "IEC 60309 plug", the complete story is here http://www.internationalconfig.com/D...4Catalog/j.pdf  


Well travelled cruisers usually mount both systems, make adapters, and use a transformer or converter of some type aboard to keep from demolishing equipment, we here always emphasized 12 volt everything when building/outfitting.