The underwriter’s knot is a knot that is used in electrical wiring to keep cords from being pulled from cord plugs. Sometimes the plug is being pulled by the cord not by the plug like it is supposed to. This results in ripping the cords from the terminal connections of the cord plug. Plugs and cords that have no built-in strain relief need something to keep them from being pulled out of the connection easily. An underwriter’s knot is a simple and effective way to support the cord within the plug and give the connection some durability. Cords are often exposed to tugging and being tripped over. In these events, the cord connection often takes a beating and often is pulled out of the plug. With the underwriter’s knot in place, the cord virtually cannot be pulled out of the plug.
Used in electrical wiring as strain relief to prevent a cable from being pulled from electrical terminals when the cable is yanked.
Underwriter’s knot, Two-strand wall knot, Electrician’s knot