Lost of all DC power

[Bay Pelican]

So how common are blown fuses without a Paul Harvey moment showing up?

My master fuse is now 31 years old. The backup is now 17 years old.

 

[rwidman]

We would expect a master fuse to only blow if there's a fault in the cable from the batteries to the 12 volt DC panel. All the branch circuits have their own circuit protection and the fuse and cable should be sized to run everything at once.


Bow thrusters and possibly windlasses would normally have their own circuits and protection and not operate off the 12 volt DC panel.

 

[hfmckevitt]

I could not locate the size of the fuse that went bad, so I used a 30amp. How could I have found the correct size. The old one was unreadable.

Henry

 

[Capt.Bill11]

I could not locate the size of the fuse that went bad, so I used a 30amp. How could I have found the correct size. The old one was unreadable.

Henry

You have to calculate the total load on the line.

You can get a idea of the possible total load by the size of the wires going to and from the fuse holder.

 

[Bacchus]

You have to calculate the total load on it.

My thinking... main line fuses are sized to protect the wire size from batty to distribution panel from overloading... sized for ampacity of conductors.

Branch circuit breakers / fuses should be sized for individual circuit loads.

 

[rwidman]

I could not locate the size of the fuse that went bad, so I used a 30amp. How could I have found the correct size. The old one was unreadable.

Henry

30 amp is way to small if we are talking about the feed from the batteries to the DC panel. Looking at the cable size and then looking this up online would tell you the proper fuse size.


Another indication would be the rating of the DC panel's main circuit breaker. If there's a difference, use the smaller fuse size.