There are three widely-used standards of enclosure ratings. One was created by NEMA (the National Electrical
Manufacturers Association), another by the IEC (International Electrotechnical Commission), and the The JIS (Japan Industrial Standards ) for water
The NEMA types most relevant to marine equipment include 3, 4, 6, and 6P.
enclosures protect against rain, snow, and sleet, as well as light splashing and airborne dust and debris. Think of type 3 as a basic indoor-outdoor enclosure.
adds protection against hosedown and heavier splashing, which makes it suitable for placement on a ship's deck
is similar to type 4, but adds protection against temporary submersion at limited depth
. This is useful for areas of a ship that may dip under the surface, or be subjected to crashing waves.
is protected against prolonged submersion, giving it the most complete resistance to water
damage of all NEMA enclosure types.
The IP (International Protection) Rating System classifies the degree of protection from solid objects, and liquids afforded by electrical equipment and enclosures.
Protection against solid objects
Second Number - Protection against liquids
protected against vertically falling drops of water (e.g. condensation)
protected against vertically falling drops of water up to 15̊ from the vertical
protected against water sprayed from all directions limited ingress permitted
protected against strong jets of water—limited ingress permitted (e.g. for use on ship decks)
protected against the effects of temporary immersion between 15 cm and 1 m
The JIS (Japan Industrial Standards) for water resistance uses a scale from 0 to 8 to quantify the level of moisture protection built into each product.
No special protection.
: Vertically dripping water shall have no harmful effect (drip-resistant 1).
Dripping water at an angle up to 15 degrees from vertical shall have no harmful effect (drip-resistant 2).
Falling rain at an angle up to 60 degrees from vertical shall have no harmful effect (rain resistant).
Splashing water from any direction shall have no harmful effect (splash resistant).
Direct jetting water from any direction shall have no harmful effect (jet resistant).
Direct jetting water from any direction shall not enter the enclosure (watertight).
Water shall not enter the enclosure when it's immersed under defined conditions (immersion-resistant).
The equipment is usable for continuous submersion in water under specified pressure (submersible).