Underwriters' Knot
Definition and meaning of Underwriters' Knot in real estate.
An underwriters' knot is a specific strain-relief knot tied in electrical cords inside fixtures, such as lamps or outlet plugs, to prevent tension on the wires from pulling them loose from their terminals.
In more detail
This safety feature is designed to reduce the risk of short circuits, electrical shocks, and house fires caused by loose wiring. The knot is named after Underwriters Laboratories, which originally mandated its use in product safety standards. By creating a physical barrier larger than the cord opening, the knot absorbs the tension when a cord is accidentally tugged.
Although it is a small detail, home inspectors and electricians verify its presence in vintage or repaired light fixtures to ensure safety compliance. It serves as an important, low-tech safety mechanism in domestic electrical systems.
Key facts
| Category | Property Types & Construction |
|---|---|
| Primary purpose | Strain relief for electrical connections |
| Common locations | Light fixtures, appliance plugs, pendant lamps |
| Safety hazard avoided | Electrical shorts and fire risks from loose wires |
An electrician rewiring a vintage brass table lamp ties an underwriters' knot in the two-conductor cord before connecting the exposed copper wires to the screw terminals of the socket.
Frequently asked questions
Why is it called an underwriters' knot?
It is named after Underwriters Laboratories, an organization that sets safety standards for electrical products.
Is the underwriters' knot still used in modern homes?
Yes, it is still used in many DIY electrical projects and repairs, though modern mass-produced appliances often use molded plastic strain reliefs instead.