Bus Plugs – Bath Tub Phenomenon
Buy PQ3206 Square D Bus Plug
MIDWEST was asked if the reliable life expectancy of bus plugs followed the classic bathtub curve. In other words, the rate of failure of bus plugs would be high when they are first put into service, ie new bus plugs. Then the failure rate would remain very low until the bus plug was very old, near the end of its reliable life. At that time the failure rate would rise again, similar to the rate when new. If one plotted the curve of the failure rate, it would have the shape of a bathtub. MIDWEST had two answers to the question. The first answer was “We don’t know, ask the manufacturer.” Our second answer was more important, “The failure rate is related to environment and not age.” We know the causes of old or new bus plug failures. New, old, and very old, obsolete bus plugs fail if they are overloaded, overheated. Bus plugs fail if they are in an area with a lot of vibration or physical movement. All bus plugs fail early in wet areas. The enclosure eventually just rusts away. New bus plugs fail if they are not properly installed. This is much more common than one might think. Old and new bus plugs fail if they get very dirty and vibrate and overheat. There isn’t much to a bus plug. So, if you install them properly and keep them dry, clean, no vibration, and under loaded, they will last for decades and you do not need to worry about the bathtub phenomenon. Sounds like a good idea for all electrical equipment.