Question: This photo shows two of the four batteries on my boat. I’m interested in finding out if the outer sheathing on both my positive and negative battery cables isn’t a bit of overkill.
The cables are all secured nicely and appear to be routed so as to be clear of any likely chafe points. Isn’t this extra layer of insulation pretty much unnecessary? I’d rather be able to track the red positive cable visually and more easily. Now it’s hidden under all the loom material. What’s up with this?
Answer: OK, a fair question. The builder in this case is following the ABYC Electrical Standard E-11 to the letter. The standard says that no over-current protection (fuse or circuit breaker) is required for the first 72 inches of cabling, measured along the conductor from the battery post. This gives builders options for locating batteries in convenient locations.
However, the standard also says that the section of unfused cabling should have insulation or protection in the form of an “enclosure” to minimize the risk of any chafe and a possible short circuit. Most builders miss this little nuance and just leave the sheathing off, but to be completely compliant they would need to sheath the cabling up to the point where the circuit protection is located, as your builder has apparently done.