GLOSSARY

ANSI – American National Standards Institute. An independent administrator and coordinator of voluntary industry standards.

bypass – A device which shunts current around the socket, so the meter can be removed without interrupting service. 

clearance – There are two, quite different meanings for "clearance." One meaning is: A specified minimum distance between two objects to assure adequate space for safety, security, or access. The other meaning is: An agreement between a foreman and the system operator, for permission. When describing new electric services, "clearance" has the first meaning – the distance between two objects.

common ground point – The point where the grounding electrode connects to the equipment-grounding conductor and/or the circuit-grounding conductor.

conduit – A pipe with a smooth interior surface for easy drawing-in of electrical conductors. Conduit may be metallic or nonmetallic.

corrosion inhibiter – An electrical joint compound used to retard oxidation at electrical connections.

current transformer – A transformer whose secondary current is a precise fraction of its primary current. Using current transformers, high-current circuits can be measured with conventional meters. Abbreviation: CT.

demand – The average rate at which energy (kilowatt hours) is consumed during a specified interval of time.

direct-burial cable – Cable which may be installed in the ground without the protection of a conduit.

direct-connect meter – A meter which carries full load current and connects across full line voltage. Also called a self-contained meter.

drip loop – A downward loop in the customer's conductors, near where the customer's conductors attach to the power company's overhead conductors, to prevent water from entering the service mast at the weatherhead.

fault – A partial or total failure of insulation which causes a short circuit between conductors, or between a conductor and ground, causing an abnormal current to flow. Also, a failure (break) in a conductor which causes an open circuit. 

fault current – A current which flows between conductors, or between a conductor and ground, due to an abnormal connection between the two. A fault current flowing to ground may be called a ground fault current.   

guy – A cable or brace that supports a mast or pole.

high leg – In a four-wire delta service, the phase with a voltage higher than the other two phases. Also called wild leg, delta leg.

instrument transformer – A transformer which delivers as its output, a precise fraction of the input line current or line voltage. Instrument transformers allow standard meters to measure high currents and voltages.

instrument-rated meter – A meter used in conjunction with instrument transformers, to measure high-voltage or high-current services. Also called a transformer-rated meter.

line conductor – A service conductor installed by the electric utility, to the meter.

load conductor – A service conductor to the customer's load, after the meter.

manual link bypass – Provision for manually installing conductive links between the line and load terminals in the meter socket. These links maintain electrical service to the customer when the meter is removed. Also called manual circuit-closing block.

manufactured home – A factory-assembled structure built on a permanent chassis, transportable in one or more sections, and designed to be used as a dwelling with a permanent foundation. Also called a modular home. New electric service to a manufactured home has the same requirements as installing new service to a permanent single-family residence.

meter jaw – A spring-loaded receptacle inside a meter socket which captures the terminals (blades) of a meter, and connects the meter terminals to the service conductors.

meter pedestal – A factory-built assembly containing a meter socket and disconnect switches.

meter ring – A metal ring which secures the meter to the meter socket, which can be sealed by the electric utility to prevent tampering with the meter.

meter socket – The mounting device consisting of meter jaws, connectors, and enclosure for receiving a socket-type meter.

mobile home – A factory-assembled structure built on a permanent chassis, transportable in one or more sections, and designed to be used as a dwelling without a permanent foundation. Overhead service to a mobile home is provided by a meter pole. Underground service to a mobile home is provided by a meter pedestal.

NEC – National Electrical Code. National regulations for the installation of electrical equipment inside buildings. Published by the National Fire Protection Association. NEC rules apply to equipment on the customer's side of the point of delivery.

NEMA – National Electrical Manufacturers Association. A trade association which publishes standards for manufacturers of electrical equipment, including enclosures and racks.

NESC – National Electrical Safety Code. National regulations for the installation, operation, and maintenance of electric supply and communication lines. Published by Institute of Electrical and Electronics Engineers. NESC rules apply to equipment on the electric utility's side of the point of delivery.

neutral – The grounded conductor in a single-phase three-wire, or three-phase four-wire system.
 
point of attachment – The point at which the utility's service conductors are mechanically attached to the customer's premises. For overhead services, the point of attachment is usually an insulated clevis.

point of delivery – The point where the utility's service line makes the electrical connection to the customer's wires. For overhead services, the point of delivery is the splice between the utility's and the customer's conductors. For underground services, the point of delivery is the secondary lugs of the distribution transformer, or the service stubout, or the secondary hand hole – if the utility's existing service is on the customer's property. If the utility's existing service is not on the customer's property, the point of delivery is the customer's property line. The utility determines the point of delivery based, in part, on convenient access to existing service.

power factor – Technically, the cosine of the phase angle between the circuit voltage and current waveforms. Since phase angles are difficult to measure, power factor is usually derived by measuring power or impedance. Power factor is the ratio of active power to apparent power (watts divided by volt-amperes). Power factor has no units, but is commonly expressed as a percentage. For example, if active power is 96 kW and apparent power is 100 kW, the power factor is 96%.

primary voltage – The voltage at which electricity is delivered from substations to distribution transformers. Primary voltage is greater than 600 volts.

raceway – An enclosed channel for holding wires or cables. If designated for line conductors, the raceway must be sealable. The intermixing of line and load conductors in the same raceway is not permitted.

seal – A locking device to secure a meter or other service equipment.

secondary voltage – The voltage at which electricity is delivered from distribution transformers to customers. Secondary voltage is less than 600 volts.

select backfill – Soil or sand free from sharp objects, rocks, scrap building material, and corrosive material.

self-contained meter – A meter which carries full load current and connects directly across full line voltage. Also called a direct-connect meter.

service drop – For overhead service, the power company's service line between the distribution transformer and the point of delivery.

service line – Conductors from the distribution transformer to the customer's point of delivery. See service drop, service lateral.

service entrance equipment – The service equipment which is supplied by the customer: conduit, conductors, mast, weatherhead, meter base, enclosures, disconnects, and panels.

service lateral – For underground service, the service line between the distribution transformer and the point of delivery.

service mast – For overhead service, the conduit rising above the meter to provide mechanical protection to the customer's conductors and to support the service drop from the power company.

socket – The mounting device for socket meters. Includes spring-loaded meter jaws, connectors for line and load conductors, and an enclosure.

temporary service – Electric service during the construction phase of a project.

test switch – A device used to isolate connections to a meter from its instrument transformers.

transformer-rated meter – A meter used in conjunction with instrument transformers, to measure high-voltage or high-current services. Also called an instrument-rated meter.

UL – Underwriters Laboratories. An independent product-testing and certification organization.

voltage transformer – A transformer whose secondary voltage is a precise fraction of its primary voltage. Using voltage transformers, high-voltage circuits can be measured with conventional meters. Abbreviation: VT, or PT (potential transformer).