Let There Be Light (34-4)

Light bulbs probably aren’t anyone’s biggest concern when they’re getting ready for a trip, but it’s a different story if you find yourself sitting in the dark.

The big windows in your RV let the sun shine in, but once it settles below the horizon you’re going to need some artificial light. Have you ever considered the lighting in your motorhome or trailer? Take a walk through and chances are, you’ll find a wide variety of different types of lights in your RV.

Incandescent Lights
The original light bulb, incandescent lights consist of a tungsten filament inside the glass. Not very efficient – the energy flowing through the filament produces about 20 percent light and 80 percent heat – they’re aptly named, as “incandescent” literally means “white hot.”

To prevent the filament from burning up when this heat is produced, it is enclosed inside the familiar glass bulb, which is filled with an inert gas that will not support combustion. Over the life of the lamp, electrons are given off by what is called thermionic emission, and this shows up as a dark coating inside the glass bulb. This builds up as the bulb ages, and reduces the amount of light that can pass through the glass.

Incandescent lights give off harsh edge shadows, since the light is emitted from a single point source. This may be further intensified if the lamp uses a reflector rather than a shade, such as in the case of a light mounted under a cabinet to illuminate a kitchen counter. The shiny metal reflector in the fixture concentrates the light downward, and protects the fixture from excessive heat developed by the lamp.

When we operate our RVs on battery power, the light output will decrease as the voltage of the battery system drops. The color of the light starts to turn yellow, and then red as the lamp produces less heat.

When we operate on electricity provided by the campground, we are connected to 60 hertz (cycles per second) of alternating current power. That means that the electricity going through the filament of our light is reversing 60 times every second. The converters in RVs change the incoming alternating 120-volt current to 12-volts of direct current, but it is generally not filtered to provide a smooth flow as it is in some newer converter systems. In most RVs, the current coming from the converter is a modified pulsating direct current. It starts at zero volts, rises to a maximum and then drops back to zero before it starts all over again, In some RVs that means that the voltage is pulsating...
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