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?
- 1Select the column with the correct insulation temperature rating of your cable
- 2Choose the right subcolumn depending whether part of the wire will run in an engine compartment or not
- 3Go 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.
- 4If more than two current-carrying cables (the negative and positive in DC circuits; 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!