E Definitions

Definition Categories


An elbow is a water pressure pipe fitting that changes the direction of flow. An elbow has a sharp angle curve that works for water under pressure but not for water and solids that flow by gravity as in drainage pipes. The terms elbow and bend are often used interchangeably, but as defined in the IRC elbows and bends are different fittings. Bends are drainage fittings and elbows are pressure pipe fittings.


An electrical component is energized if it is connected to a voltage source. A common term for energized is that the component is “hot”.


Equipment includes pipes, ducts, vent, control devices and similar installed devices when the term describes components in the HVAC system. Equipment does not refer to appliances such as furnaces, water heaters, and air conditioning condensers. Equipment is also a general term used to describe components in the electrical system including electrical appliances, lights, boxes, and fittings.

Exposed (parts)

Parts in an electrical system are exposed when they might be accidentally touched or approached at an unsafe distance by a person. Exposed parts include metal cabinets and enclosures, boxes, and conduit. Exposed electrical parts should be grounded to reduce the chance of electrical shock.

Exposed (wires)

Wires are exposed when they are run along an accessible surface or when they are run behind panels that allow access.  Almost all wires that are not permanently covered by drywall or other finish materials are considered exposed.


Exposure is the amount of material visible when installed. The term is used in roof coverings to describe how much of a shingle is visible below the head lap of the shingle course above. See Head lap.

Exterior wall

Exterior walls include above-grade and basement walls.