Check your Fuse and Buss Bar Connections

IslandHopper

Member
Joined
Feb 25, 2025
Messages
8
Fluid Motion Model
R-27 (Outboard)
Hull Identification Number
FMLT2742J425
Vessel Name
Tugether Atlas
MMSI Number
316056612
After a run on the boat last week, we were running the inverter while docked, doing our routine cleanup and running the AC and various other loads totaling around 180 amps. While I was flushing the drains and scuppers with the hatches open and I started to smell the familiar scent of burning wire, looking over at the port side hatch I saw a wiff of smoke. In a panic we shut everything down with fire extinguishers ready and I started feeling wires and visually tracking down where the smoke came from, which was the Inverter Fuse Block that had melted
Melted part Sz.jpg

After some troubleshooting, I determined that the 350A ANL Fuse for the Inverter was installed incorrectly, with the stainless washer in between the fuse and the buss. I won’t get into the technical details (unless someone wants), but in this configuration the stainless washer adds resistance, which is heat, which can lead to a fire.
Close up of washer on wrong side Sz.jpg

Upon further investigation, I noticed that the Main Fuse and connections to the Main Buss also had similar incorrect installations.
House Main Fuse Sz.jpg


I’d just like to suggest to everyone – next time you are on your boat (no matter what make or model), have a quick look at the fuse connections and all buss connections. If there is a washer in between the cable connector and buss – fix it or take it to a dealer that will install it correctly. Look up the manufacturers’ model for the fuse and buss blocks and ensure they are installed and torqued to proper specifications.

Our boat is a 2025 R27 LE with a 640A Lithium House battery bank. The Blue Sea Systems ANL fuse block has a Maximum torque spec of 107 in Lbs. The BEP Main buss Recommended torque is 190 in lbs (15.9 FtLbs). Please verify your specific models with manufactures specifications.
 
I was surprised a bit but on doing a bit of research google tells me
Yes, stainless steel washers can add significant and problematic resistance to an electrical circuit. They possess only about 8% the electrical conductivity of copper. In high-current applications, this high resistance generates dangerous heat, potentially causing blown fuses, melted fuse holders, or fires
 
Thank you for letting everyone know. This is a very important warning and the assessment is spot on.
 
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