Project Atticus – Interview with Nigel Calder

During a live interview with Jordan from Project Atticus, BoatHowTo co-founder Nigel Calder goes into the details of wiring and overcurrent protection for high-output alternators.


In this video, Nigel made a mistake! He was doing the voltage drop calculations in his head during the discussion and screwed it up, luckily on the conservative side! He estimated the voltage drop with the 3/0 conductor at more-or-less twice what it will be. 

If you run the calculations using our wire sizer you will find that from a voltage drop perspective Jordan can get away with a single 3/0 conductor so the second 3/0 conductor is not really necessary.

It would still have been better from an ampacity and overcurrent perspective to have used the 4/0 conductor but as Nigel says, given that Jordan’s alternator will not put out its rated output for more than a few minutes he would not lose sleep over this. Bottom line: we all make mistakes so it is important to run the numbers and not rely on guesswork!

If you want to learn more about the topic, we have a special case study on high-output alternators in our Boat Electrics 101 online 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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