In electrical engineering, ground or earth may be a reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth.
A surge protector (or spike suppressor, surge suppressor, surge diverter, surge protection device (SPD), transient voltage suppressor(TVS) or transient voltage surge suppressor (TVSS)) is an appliance or device intended to protect electrical devices in alternating current (AC) circuits from voltage spikes with very short duration measured in microseconds, which can arise from a variety of causes including lightning strikes in the vicinity.
Electrical wiring in North America follows the regulations and standards applicable at the installation location. It is also designed to provide proper function, and is also influenced by history and traditions of the location installation.
The National Electrical Code (NEC), or NFPA 70, is a regionally adoptable standard for the safe installation of electrical wiring and equipment in the United States. It is part of the National Fire Code series published by the National Fire Protection Association (NFPA), a private trade association. Despite the use of the term "national," it is not a federal law. It is typically adopted by states and municipalities in an effort to standardize their enforcement of safe electrical practices. In some cases, the NEC is amended, altered and may even be rejected in lieu of regional regulations as voted on by local governing bodies.
An isolation transformer is a transformer used to transfer electrical power from a source of alternating current (AC) power to some equipment or device while isolating the powered device from the power source, usually for safety reasons or to reduce transients and harmonics. Isolation transformers provide galvanic isolation; no conductive path is present between source and load. This isolation is used to protect against electric shock, to suppress electrical noise in sensitive devices, or to transfer power between two circuits which must not be connected. A transformer sold for isolation is often built with special insulation between primary and secondary, and is specified to withstand a high voltage between windings.
A lightning arrester is a device, essentially an air gap between an electric wire and ground, used on electric power transmission and telecommunication systems to protect the insulation and conductors of the system from the damaging effects of lightning. The typical lightning arrester has a high-voltage terminal and a ground terminal. When a lightning surge travels along the power line to the arrester, the current from the surge is diverted through the arrester, in most cases to earth.
High voltage electricity refers to electrical potential large enough to cause injury or damage. In certain industries, high voltage refers to voltage above a certain threshold. Equipment and conductors that carry high voltage warrant special safety requirements and procedures.
British Standard BS 7671 "Requirements for Electrical Installations. IET Wiring Regulations", informally called in the UK electrical community "The Regs", is the national standard in the United Kingdom for electrical installation and the safety of electrical wiring systems.
An earthing system or grounding system (US) connects specific parts of an electric power system with the ground, typically the equipment's conductive surface, for safety and functional purposes. The choice of earthing system can affect the safety and electromagnetic compatibility of the installation. Regulations for earthing systems vary among countries, though most follow the recommendations of the International Electrotechnical Commission (IEC). Regulations may identify special cases for earthing in mines, in patient care areas, or in hazardous areas of industrial plants.
Extra-low voltage (ELV) is an electricity supply voltage and is a part of the low-voltage band in a range which carries a low risk of dangerous electrical shock. There are various standards that define extra-low voltage. The International Electrotechnical Commission (IEC) and the UK IET define an ELV device or circuit as one in which the electrical potential between two conductors or between an electrical conductor and Earth (ground) does not exceed 120 volts (V) for ripple-free direct current (DC) or 50 VRMS for alternating current (AC).
Lock out, tag out or lockout–tagout (LOTO) is a safety procedure used to ensure that dangerous equipment is properly shut off and not able to be started up again prior to the completion of maintenance or repair work. It requires that hazardous energy sources be "isolated and rendered inoperative" before work is started on the equipment in question. The isolated power sources are then locked and a tag is placed on the lock identifying the worker and reason the LOTO is placed on it. The worker then holds the key for the lock, ensuring that only that worker can remove the lock and start the equipment. This prevents accidental startup of equipment while it is in a hazardous state or while a worker is in direct contact with it.
NFPA 70E(Standard for Electrical Safety in the Workplace) is a standard of the National Fire Protection Association (NFPA). The document covers electrical safety requirements for employees. The NFPA is best known for publishing the National Electrical Code.
An arc flash is the light and heat produced as part of an arc fault, a type of electrical explosion or discharge that results from a connection through air to ground or another voltage phase in an electrical system.
In electrical engineering, low voltage is a relative term, the definition varying by context. Different definitions are used in electric power transmission and distribution, compared with electronics design. Electrical safety codes define "low voltage" circuits that are exempt from the protection required at higher voltages. These definitions vary by country and specific codes or regulations.
IEEE 1547 is a standard of the Institute of Electrical and Electronics Engineers meant to provide a set of criteria and requirements for the interconnection of distributed generation resources into the power grid.
A lightning rod or lightning conductor is a metal rod mounted on a structure and intended to protect the structure from a lightning strike. If lightning hits the structure, it is most likely to strike the rod and be conducted to ground through a wire, rather than passing through the structure, where it could start a fire or even cause electrocution. Lightning rods are also called finials, air terminals, or strike termination devices.
ANSI Z535 are American-developed standards designed to improve the identification of potential hazards to workers and/or property. The identifications are called Hazardous Communication (HazCom). ANSI Z535 sets the design and application standards for all HazCom used across North America and globally, in most industrialized nations. ANSI Z535 standards integrate with international ISO 3864 standards, ensuring the widest compliance, globally, with export/import laws. ANSI Z535 standardized HazCom may appear on workplace walls, industrial machines, at industrial access points, on electrical controls, inside product user guides, and on export documentation.
The National Electrical Safety Code (NESC) or ANSI Standard C2 is a United States standard of the safe installation, operation, and maintenance of electric power and communication utility systems including power substations, power and communication overhead lines, and power and communication underground lines. It is published by the Institute of Electrical and Electronics Engineers (IEEE). "National Electrical Safety Code" and "NESC" are registered trademarks of the IEEE.
Mr. Ouch is a hazard symbol developed by the US’s National Electrical Manufacturers Association (NEMA) to represent electrical hazard within pad-mounted transformers. Unlike other high-voltage warning symbols, Mr. Ouch was specifically designed with young children in mind. It is part of NEMA Standard 260-1996, Safety Labels for Pad-Mounted Switchgear and Transformers Sited in Public Areas, which lays out design guidelines for a complete label design that incorporates the Mr. Ouch symbol.
Workplace safety standards are sets of standards developed with the goal of reducing risk from occupational hazards.
