Glossary of Meter Terms

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

active power Accumulated over time, active power is measured by watthour meters and is what most customers are billed for. The line current squared, times resistance. (I squared R). Measured in watts.

apparent power The total power generated by the utility for one customer, or for a group of customers. Line voltage times line current (volt-amperes).

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

clearance There are two, quite different meanings for the word "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 meter 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 See 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.

energy Average rate at which work is done multiplied by how long the power has been consumed. 1 watthour the energy expended in one hour when the power is 1 watt. Measured by: watthour meter. (Comparable to an odometer). See also: power.

fault current The maximum current that would flow if a short circuit occurred.

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. Identify the high leg with orange marking.. Also: wild leg, delta leg. Typically the high leg is 208 volts single-phase, and has no practical use because there are no 208-volt single- phase appliances.

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 See transformer-rated meter.

line conductor A service conductor from the power company, before 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. See also, mobile home.

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 power company 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. See also, manufactured home.

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 for Electrical and Electronic Engineers. NESC rules apply to equipment on the power company'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 power company'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 power company's service line makes the electrical connection to the customer's wires.

power Instantaneous rate at which work is done. 1 watt = the power expended when 1 ampere flows through 1 ohm. Measured by a wattmeter. (Comparable to a speedometer). See also, energy.

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 on the power company side of a distribution transformer. 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.

reactive power Power that circulates in the wires. It is consumed in alternatively building and collapsing AC magnetic fields in transformers and motor windings, and electrostatic fields in capacitors. Measured as volt-amperes reactive (VARs).

seal A locking device to secure a meter or other service equipment, usually to discourage tampering..

secondary voltage The voltage on the customer side of a distribution transformer.

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 power company's transformer and the point of delivery.

service line Conductors from the power company's 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 power company's 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 Electrical 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.

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).