Which of the following is not a likely source of stray current corrosion (electrolytic)?

Stray current corrosion, also known as electrolytic corrosion, occurs when an electrical current runs through water, leading to accelerated corrosion of metals. Sources of stray current corrosion typically involve electrical faults or issues that result in unintended current paths near or in the water, impacting metallic parts of boats and other structures.

A lifeline failure due to corrosion would not be a source of stray current. Rather, it is an outcome or effect associated with corrosion damage. While lifelines are metal components and can certainly corrode over time, their failure is more related to traditional corrosion mechanisms, such as galvanic corrosion or environmental factors, rather than the presence of stray currents from electrical faults.

In contrast, a faulty bilge pump float switch and a faulty battery charger with a ground fault are both examples of electrical issues that can create unintended stray currents in the water. Additionally, faults from neighboring boats may also contribute to stray current situations if their electrical systems are leaking currents into the surrounding water, which can affect nearby vessels and metallic components. Thus, the lifeline's failure occurrence does not implicate stray current but rather results from standard corrosion processes, making it the answer that does not align with the definition of stray current corrosion sources.