Article 100 NEC Definitions (Letter O)

1. Office Furnishing
This refers to cubicle panels, partitions, study carrels, workstations, desks, shelving systems, and storage units that can be mechanically and electrically interconnected to form an office furnishing system.
(CMP—18)

2. Oil Immersion
Electrical equipment immersed in a protective liquid to prevent ignition of any explosive atmosphere that might be above the liquid or outside the enclosure.
(CMP—14)
Informational Note: See ANSI/UL 121201 for further information.

3. Open Wiring on Insulators
An exposed wiring method using cleats, knobs, tubes, and flexible tubing to protect and support insulated conductors within or on buildings.
(CMP—6)

4. Operating Device
A device like a car switch, pushbuttons, key or toggle switches, used to activate an operation controller.
(CMP—12)

5. Operator
The person responsible for starting, stopping, and controlling an amusement ride or supervising a concession.
(CMP—15)

6. Optical Radiation
Electromagnetic radiation with wavelengths between 1 nm and 1000 µm, falling between X-rays and radio waves.
(CMP—14)
Informational Note: See ANSI/UL 60079-28 for additional protection information.

7. Inherently Safe Optical Radiation («op is»)
A protection type to minimize ignition risk in explosive atmospheres where visible or infrared radiation cannot produce enough energy to ignite the atmosphere.
(CMP—14)
Informational Note: See ANSI/UL 60079-28 for more details.

8. Protected Optical Radiation («op pr»)
A protection type where radiation is confined within optical fibers or other mediums, preventing escape of radiation under normal or mechanical protection.
(CMP—14)
Informational Note: For further information, consult ANSI/UL 60079-28.

9. Optical System with Interlock («op sh»)
A system that confines optical radiation within optical fibers, with an interlock cutoff to reduce unconfined radiation to safe levels if the system fails.
(CMP—14)
Informational Note: See ANSI/UL 60079-28 for more information.

10. Optional Standby Systems
Systems designed to supply power to facilities where life safety does not depend on the system’s performance. These systems provide power to selected loads either automatically or manually.
(CMP—13)

11. Electronic Organ
A musical instrument that replicates pipe organ sounds using electronic means.
(CMP—12)
Informational Note: Most modern electronic organs produce sound digitally, called digital organs.

12. Pipe Organ
A musical instrument that produces sound by forcing pressurized air through pipes controlled by a keyboard.
(CMP—12)

13. Pipe Organ Sounding Apparatus
The sound-producing part of a pipe organ, including pipes, chimes, bells, and the blower that generates pressurized air.
(CMP—12)

14. Outlet
A point on the wiring system where current is supplied to utilization equipment.
(CMP—1)

15. Outlet Box Hood
A housing shield that fits over a faceplate to protect electrical components from water contact, such as attachment plugs and wiring devices.
(CMP—18)

16. Outline Lighting
An arrangement of lamps or lighting sources used to outline or highlight features, like the shape of a building or window decorations.
(CMP—18)

17. Output Cable to the Electric Vehicle
A flexible cable assembly that connects to an electric vehicle to supply power.
(CMP—12)

18. Output Cable to the Primary Pad
A cable assembly used to carry high-frequency energy and status signals between a charger power converter and a primary pad.
(CMP—12)

19. Overcurrent
Any current that exceeds the rated current of equipment or the ampacity of a conductor, which can be caused by overload, short circuit, or ground fault.
(CMP—10)
Informational Note: Overcurrent protection is specific to the conditions of each situation.

20. Branch-Circuit Overcurrent Protective Device
A device that protects service, feeder, and branch circuits from overcurrent conditions within its rated range.
(CMP—10)

21. Current-Limiting Overcurrent Protective Device
A device that limits the current during faults to a much lower value than that in the circuit with a similar impedance conductor.
(CMP—10)

22. Supplementary Overcurrent Protective Device
A device that provides additional limited protection for specific applications or equipment, complementing the branch-circuit overcurrent device.
(CMP—10)

23. Overhead Gantry
A structure consisting of horizontal framework supported by vertical columns above electrified truck parking spaces, providing services like electricity, HVAC, and communications.
(CMP—12)

24. Overload
Operating equipment above its rated load or a conductor beyond its ampacity, which, if prolonged, can lead to overheating or damage. It does not involve faults like short circuits.
(CMP—10)

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Summary Table of Terms and Definitions

Term	Definition
Office Furnishing	Mechanically and electrically interconnected cubicle panels, workstations, and storage units. (CMP—18)
Oil Immersion	Equipment immersed in protective liquid to prevent ignition. (CMP—14)
Open Wiring on Insulators	Exposed wiring method using cleats, tubes, and flexible tubing for conductor protection. (CMP—6)
Operating Device	Devices used to activate operation controllers. (CMP—12)
Operator	Individual responsible for operating amusement rides or supervising concessions. (CMP—15)
Optical Radiation	Electromagnetic radiation with wavelengths between 1 nm and 1000 µm. (CMP—14)
Inherently Safe Optical Radiation («op is»)	Type of protection against ignition risks in explosive atmospheres where radiation is harmless. (CMP—14)
Protected Optical Radiation («op pr»)	Optical radiation confined to mediums like fibers to prevent escape. (CMP—14)
Optical System with Interlock («op sh»)	Protection system that minimizes radiation escape risks. (CMP—14)
Optional Standby Systems	Systems designed to supply power without life-safety dependencies. (CMP—13)
Electronic Organ	A musical instrument that simulates pipe organ sounds electronically. (CMP—12)
Pipe Organ	A musical instrument producing sound by driving air through pipes. (CMP—12)
Pipe Organ Sounding Apparatus	The sound-producing parts of a pipe organ, including pipes and the air blower. (CMP—12)
Outlet	The point on the wiring system where current is supplied to equipment. (CMP—1)
Outlet Box Hood	A shielded housing that protects electrical components from water. (CMP—18)
Outline Lighting	Lighting arrangement to highlight building features. (CMP—18)
Output Cable to the Electric Vehicle	Flexible cable assembly supplying power to an electric vehicle. (CMP—12)
Output Cable to the Primary Pad	Cable carrying energy and status signals between charger and primary pad. (CMP—12)
Overcurrent	Current exceeding equipment ratings or conductor capacity. (CMP—10)
Branch-Circuit Overcurrent Protective Device	A device protecting circuits from overcurrent. (CMP—10)
Current-Limiting Overcurrent Protective Device	A device that limits current during faults. (CMP—10)
Supplementary Overcurrent Protective Device	Provides additional overcurrent protection for specific equipment. (CMP—10)
Overhead Gantry	Structure supporting services like electricity and communications above truck parking. (CMP—12)
Overload	Equipment or conductor operation above normal rating, potentially causing overheating. (CMP—10)