ABYC Ampacity Tables

On this page, you can download the official ampacity tables from the ABYC E-11 standard as PDF. They are the basis for calculating wire sizes on your boat. We also included the ABYC voltage drop tables.

If you are outside of the US, you might want to check out the ISO ampacity tables instead. 

How to use the ABYC ampacity tables?

  1. 1
    Select the column with the correct insulation temperature rating of your cable
  2. 2
    Choose the right subcolumn depending whether part of the wire will run in an engine compartment or not
  3. 3
    Go down that column until you reach the row with the size of the cable according to the AWG system.
    This gives you the ampacity of the cable if it is not in a bundle.
  4. 4
    If more than one current-carrying cables in DC circuits (e.g. the negative and positive) or more than two current-carrying cables (the hot and neutral) in AC are run together, you have to derate the ampacity. Just multiply it by the derating factors in the small table. The factors vary whether we have a DC or AC applications and according to the number of cables in a bundle.

If you want to know the required wire size for a given ampacity, just do the whole process in reverse.

Instead of doing the calculations by hand, you can also use the BOATHOWTO Wire Size Calculator.

If you want to know more details on the choice of cables for your boat, the required overcurrent protection and much more, check out our Boat Electrics course!

About the author 

Nigel Calder

Nigel is often referred to as THE guru when it comes to technical systems on boats.

He is a long-time member of the American Boat and Yacht Council (ABYC) electrical Project Technical Committee (PTC) which writes the standards for recreational boat systems in the USA, and has also been involved in European standards development.

Nigel is best known for his Boatowner’s Mechanical and Electrical Manual (now in its 4th edition), and his Marine Diesel Engines (in its 3rd edition), both considered the definitive English-language works in their field.

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