Advanced Marine Electrics and Electronics Troubleshooting A Manual for Boatowners and Marine Technicians

potential problems. Here we’ll go over both

the NMEA and ABYC standards related to

temperature control.

The NMEA standard refers to “equipment

that requires air circulation for cooling,”

which I consider to be any piece of gear that is

equipped with a built-in cooling fan, mounted

on a heat sink, or has finned radiating plates as

part of its enclosure. The NMEA standard

states that “sufficient means shall be provided

to supply circulation of air behind the equip-

ment displays.” And for devices that use cool-

ing fans, it states “there shall be sufficient air

circulation to cool the equipment during

direct sunlight operation with ambient tem-

peratures of 100°F.”

The ABYC is quite specific about temper-

ature parameters in two of its standards. Stan-

dard A-31 requires that battery chargers and

inverters be designed to operate at an ambient

temperature of 122° (50°C) and be able to

withstand an ambient temperature of 158°F

(70°C). ABYC A-28 requires galvanic isola-

tors that will be installed in machinery spaces

be rated to 122°F, while those that will not be

used in machinery spaces be rated to 86°F

(30°C).

In addition, manufacturers establish their

own installation guidelines regarding temper-

ature. ICOM, for example, states in the docu-

mentation for one of its SSB transceivers that

it should not be mounted in locations subject

134 marine electronics installation and troubleshooting

Protection Against Protection Against

1st Digit Foreign Objects 2nd Digit Moisture

0 Not protected 0 Not protected

1 Protected against objects 1 Protected against dripping water

greater than 50 mm

2 Protected against objects 2 Protected against dripping water

greater than 12 mm when tilted up to 15°

3 Protected against objects 3 Protected against spraying water

greater than 2.5 mm

4 Protected against objects 4 Protected against splashing water

greater than 1.0 mm

5 Dust protected 5 Protected against water jets

6 Dust tight 6 Protected against heavy seas

—— 7 Protection against the effects of

temporary immersion up to 1 m

—— 8 Protection against prolonged

submersion beyond 1 m

Note:The letter X is used to designate no rating in either category.

Source:Underwriters Laboratories

Environmental Ratings for Enclosures Based on Ingress Protection (IP)

Code Designations

TABLE

13-1