W Definitions

Definition Categories

Water service pipe

The water service pipe begins at the water source (the water meter or well) and ends at the main water shut off valve at or in the home. Water distribution pipe Water distribution pipes begin at the main water shut off valve at or in the home and end at a water supply fixture such as a sink.


The term wire, defined as a conductor of electricity, is not formally used in the IRC. The preferred term is conductor. See the definition of conductor.


Wiring methods

Wiring methods describes wires, cables, conduit, and tubing that one may use as service entrance wires, feeder wires, and branch circuit wires. The most common wiring method in modern residential construction is nonmetallic sheathed cable, abbreviated NM, and often referred to by the trade name Romex®. Other common residential wiring methods include service entrance cable (SE), and various types of electrical conduit and tubing.


A wye is usually a fitting with 3 openings. Two openings are in a straight line and one opening is at an approximate 45┬░ angle to the others. Wye fittings can be made with other fittings to make combination fittings such as a tee-wye and a combination wye and 1/8 bend. Double wye and double tee-wye fittings are also available.


A wythe (also spelled withe) describes a masonry wall one masonry unit thick. A brick wall that is one brick wide is said to be one wythe of brick.