Why use "Marine Grade" electrical wire?
Marine installations are subjected to constant moist conditions along with
motion and vibration.
Marine grade wiring products are designed to minimize the corrosion associated with moist conditions with a layer of Tin over the fine stranded copper conductors.
Marine grade wiring products have finer stranding to:
Facilitate the more difficult installations and allow the flexing of the conductors normal movement, without the stress that would be placed on coarse stranded or solid conductors.
Ancor - Marine Grade Electrical Wire
Pacer Marine - Marine Quality Electrical Wire