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| Hazardous electrical location classifications
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Hazard classifications as established by the National Electrical Code: |
| Hazing
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Paint defect, which makes the finish surface cloudy. |
| Head
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A unit of pressure for a fluid, commonly used in water pumping and hydro power to express height a pump must lift water, or the distance water falls. Total head accounts for friction head losses, etc. |
| Head casing
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Framework at the top of a window. |
| Head jamb
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Also called a yoke, it's the upper horizontal finish member in a window frame. |
| Head joint
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Joint between the ends of two masonry units. |
| Head lock screw
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The head lock screw is a safety feature that locks a drill press head to the drill press column. Always lock the head when the drill is in use. |
| Head loss
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The pressure of water as measured at a stated point, either in feet or in pounds per square inch (PSI). |
| Head plate
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Also called a wall plate, this horizontal structural piece is anchored to a masonry wall. Other structural pieces may be supported from it. |
| Head pressure
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Maximum amount of pressure against which a pump can move fluid. |
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