A door loop or door cord is a

mechanical Mechanical may refer to: Machine * Machine (mechanical), a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement * Mechanical calculator, a device used to perform the basic operations of ...

device which provides a robust guideway for cabling between a

swing door A door is a hinged or otherwise movable barrier that allows ingress (entry) into and egress (exit) from an enclosure. The created opening in the wall is a ''doorway'' or ''portal''. A door's essential and primary purpose is to provide security b ...

(the "door leaf") and a

door frame A door is a hinged or otherwise movable barrier that allows ingress (entry) into and egress (exit) from an enclosure. The created opening in the wall is a ''doorway'' or ''portal''. A door's essential and primary purpose is to provide security by ...

. Door loops are described in the NFPA 80 standard for

fire doors A fire door is a door with a fire-resistance rating (sometimes referred to as a ''fire protection rating'' for closures) used as part of a passive fire protection system to reduce the spread of fire and smoke between separate compartments o ...

.{{Cite web, title=NFPA 80: Standard for Fire Doors and Other Opening Protectives, url=https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=80, access-date=2021-10-02, website=www.nfpa.org

Motivation

Door loops are used in cases where electrical components are mounted in the door leaf, like for example a motorized door lock,

smart lock A smart lock is an electromechanical lock that is designed to perform locking and unlocking operations on a door when it receives a prompt via an electronic keypad, biometric sensor, access card, Bluetooth, or Wi-FI from a registered mobile devic ...

smart doorbell A smart doorbell is an internet-connected doorbell that notifies the smartphone or other electronic device of the home owner when a visitor arrives at the door. It activates when the visitor presses the button of the doorbell, or alternatively, wh ...

solenoid bolt A solenoid bolt is a type of electronic-mechanical locking mechanism. This type of lock is characterized by the use of a solenoid to throw the bolt. Pawl & solenoid locking mechanism, Inventor(s): BUTTERWECK DIETER E PHILLIPS PETER J S GART ...

. Since the

hinges A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation: all other ...

move during operation, a normal laying of cable would quickly wear out. The door loop also ensures that the twisting of the cables is distributed over a longer cable length, which is decisive for the wear of the cables.

Mounting

Normally, the door loop is mounted inside the door frame ("concealed door loops"), and can not be seen except for when the door is open. Another type is surface mounted transfers which serve the same function ("visible door loops"), which normally can be seen on the top of the door at all times.

References

Locksmithing