One of the things that sets apart boat lighting from most other typical household or business type lighting is the oftentimes highly specialized nature of the fixtures. Depending on the installation location and the intended use, light fixtures used on boats can be highly specialized in their design in order to meet the specific and unique conditions created by the marine environment. Unlike household lighting where a typical light bulb radiating light over 360 degrees of area is usually adequate enough for illuminating rooms, porches, closets and the like, the unusual structural design of a boats interior and the harsh conditions of the marine environment can make providing illumination something of a challenge.
The first and most obvious difference between boat lighting and typical household lighting is dampness, humidity and wetness associated with a marine environment. Wetness and humidity are the biggest enemies of metals and electrical devices. Constant exposure causes accelerated corrosion and rust, and unless fixtures are properly designed and protected, will destroy fixtures in a very short period of time. Even fixtures installed below decks are susceptible to the effects of high humidity and must be able to withstand such conditions. The moisture problem is greatly intensified by the high levels of a marine environment. Many boats spend the majority of their time exposed to not only the salt water of the ocean, but the air around the ocean which also contains elevated salt levels as well. As most boaters already know, moisture with high salt content reacts almost immediately with most metals and causes rust and corrosion to occur at an alarmingly fast rate.
One of the less obvious, but perhaps one of the more critical problems boaters face is providing SAFE illumination. Most people do not usually associate lighting with potential fire and explosion hazards, but onboard a boat this is a very real problem that is more common than many boaters probably realize. For most locations onboard, standard marine grade light fixtures are entirely adequate, but in the engine room, a different type of fixture is necessary. Commonly called “explosion proof”, these special fixtures are designed to prevent the accidental ignition of flammable gases and vapors that may be present in the surrounding atmosphere. These types of flammable gases can be present in an engine room due to the gas lines and fittings that supply fuel to the engines. If a leak occurs, it is entirely possible for gasoline vapors to accumulate in dangerous amounts within the confines of a closed engine room in a very short period of time.
Lighting can present a fire or explosion hazard not because the lamp itself gets hot enough to cause ignition, although this is also a lesser possibility, but because the switches that activate the light and the contacts within the fixture can create sparks which can ignite flammable gases and vapors. In an atmosphere that is saturated with gasoline vapors, ignition can occur with something as minor as a discharge from static electricity. These highly volatile vapors, confined within the small area of the engine room, once ignited can burn with explosive force, in many cases with as much force as a small bomb. If for example a fuel leak occurs while you are cruising offshore, the engines may shut down. You then go into the engine room to determine what the problem is, and the first thing you do is reach for the light switch. Since you are unaware that a fuel leak has occurred, it is entirely possible for you to ignite the now flammable air within the engine room simply by flicking on the light switch. Obviously, this is a serious problem and thus preventing ignition from occurring is critical to maintaining safety.
Explosion proof engine room lights provide protection against this potential ignition of flammable or explosive engine room atmospheres. The special design of an explosion proof lamp prevents ignition in one of two primary ways, either by completely sealing off all the internal components from the outside atmosphere, or by containing any ignitions within the lamp body. In sealed versions, all of the electrical components including switches, contacts and any internal wiring and contacts are enclosed either within a fully gasketed fixture body, or the electrical parts are sealed within a potting material such as acrylic or polymer. Fixtures which contain ignitions within the lamp body are not fully sealed, but instead rely on a special design that forces any gases that ignite within the housing to pass through a length of threads or channels, and by the time these ignited gases exit from the channels they have cooled enough to no longer be capable of igniting the outside atmosphere.
Another type of fixture which protects against ignitions is the intrinsically safe fixture. These fixtures are different in that rather then being completely sealed or containing ignitions, they are incapable of producing the heat or sparks which could cause ignition. As a result, intrinsically safe fixtures provide the highest level of protection against ignition. The main drawback to intrinsically safe fixtures is that they typically run with very low voltages, thus limiting the amount of illumination they can produce. Intrinsically safe fixtures are usually used in applications where minimum light output is acceptable, such as with flashlights or small indicator type lamps. Newer intrinsically safe LED fixtures produce more light than most typical types of intrinsically safe lamps, but are still of generally lower power output.
A final, and critical consideration when choosing an explosion proof engine room light is ensuring you choose a lamp with the proper classification. Explosion proof lamps are classed according to the types of materials they come into contact with and the likelihood of the hazard being present. For engine room use, a fixture with either an intrinsically safe rating or a Class 1 Division 1 or 2 rating is normally sufficient to provide adequate protection. Class 1 refers to the presence of flammable gases or vapors, and Division 2 refers to them being present occasionally such as in result of leaks spills. A Class 1 Division 1 fixture would provide greater all around protection as it refers to gases and vapors being present on a continual basis. In either of these cases, this type of explosion proof engine room light will provide the added protection a boater needs to help avoid a potential fire or explosion hazard should the air in the engine room become saturated with flammable gasoline vapors.
