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Construction Services - Electric and Lighting Glossary of Terms

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Ampacity: The current in amperes a conductor can carry continuously under the conditions of use without exceeding its temperature rating.

Amperage, Ampere, Amp:
Amperage is the volume (or quantity) of electrical current flowing through a circuit. This volume is measured in amperes, otherwise referred to as amps.

Anti-Inversion Clip:
An insert into a meter socket that will reduce the size of the number three position to allow meters with a reduced spade to fit into the jaws of the socket. Used to prevent class 200 meters from being installed in 320 amp continuously rated meter devices.

A person who applies for Residential or Non-Residential service and/or who requests a service extension.

Acceptable to the authority having jurisdiction. See: Local Inspection Authority.

Automatic Meter Reading (AMR)
: A system installed to read a utility meter remotely

A group of electrical devices, usually transformers, meters or capacitors, connected in a way to increase capacity.

Base load:
The minimum amount of electric power delivered or required over a given period of time at a steady rate.

A concrete filled 4 inch diameter iron pipe or railroad rails installed by the customer to protect Ameren Missouri electric facilities.

Bonding Conductor:
The conductor that provides the required electrical conductivity between metal parts that are required to be electrically connected.

Service extended to meter location by attaching conductors to multiple house knobs.

Bypass, Horn Type:
Tabs are located on the line and load side of a ring-less type meter socket which allow utility personnel to install special jumper cables between the line and load side of the meter. This will divert the current flow from the meter to the temporarily installed jumpers. This allows for the exchange, inspection or repair of a meter without a service interruption to the customer.

Bypass, Locking Lever Jaw Type:
A mechanical lever bypass is an integral component designed into the meter socket block assembly of a ring-less type meter socket. The lever action has two primary functions:

    (1) When engaged downward, the mechanism provides jaw clamping forces to help secure the meter and make continuity to the meter spades while in normal operation.

    (2) When engaged upward into “bypass” mode, the mechanism releases the clamping pressure on the meter spades and diverts the current flow from the meter to the internal bypass. This allows for the exchange, inspection or repair of a meter without service interruption to the customer. Note: Meter cover cannot be reinstalled or sealed with lever handle in upward “bypass” position.

The capability to generate electrical power, measured in megawatts (MW) or kilowatts (kW).

A conductor or a system of conductors through which electric current flows.

Circuit Breaker(s):
A safety device designed to automatically stop the flow of electricity whenever a circuit becomes overloaded, i.e. exceeds the number of amps that the wiring can accommodate.

Various government bodies have adopted minimum safety standards, or “codes” for the electrical wiring. See NEC and NESC also.

The agency responsible for regulating the regulated portions of investor-owned public utilities. In Missouri, the Missouri Public Service Commission (PSC) or any duly constituted successor.

Union Electric Company dba Ameren Missouri acting through its duly authorized officers, agents or employees within the scope of their respective duties and authorities.

A material that carries electrical current usually wires or cables.

A channel for holding and protecting conductors and cables, made of metal or an insulating material, usually circular in cross section like a pipe.

Conduit System:
The joining of multiple conduits to provided a channel for holding and protecting conductors and cables from one piece of electrical equipment to another.

Corps of Engineer:
Refers to the United States Army Corps of Engineers.

Any person, developer, firm, organization, association, corporation or other entity legally receiving service at a Premise or whose facilities are connected for utilizing service at the Premises.

Current Transformer (CT):
A transformer used to measure the amount of current flowing in a circuit. Its primary winding is rated in excess of the expected current of the circuit and the secondary will normally be rated at 5 amps being equal to the nominal full primary current.

Delivery Voltage:
The voltage of Company’s lines at the Point of Delivery.

The entity responsible for constructing and making improvements to a tract of land (streets, sidewalks, storm sewers, utilities, etc.) for the creation of a Residential and/or Non-Residential development.

A lot, tract, or parcel of land divided into two or more lots, plots, sites or other divisions for use for two or more new Residential or Non-Residential buildings or the land on which is constructed new multiple-occupancy Residential or Non-Residential buildings per a recorded plat.

Dig Rite:
Also known as Missouri One Call.

The delivery of electricity to Residential and Non-Residential customers or facilities.

Distribution System:
For the purpose of determining Line and/or Service Extension applicability, means those poles, wire, and other equipment used to distribute electricity either overhead or underground at 69kV or less.

Drip Loop:
Slack of the overhead wires between the brackets and weatherhead. This allows rainwater to collect and drip down before reaching the weatherhead.

A Residential building consisting of two units that share a common wall.

A formal permission granted by landowners for installation and maintenance of facilities. Easements are commonly referred to as right-of-way grants.

Refers to the United States Federal Aviation Administration.

Flying Loop:
A connection made in the middle of the span, when trees, buildings, or other obstructions make it impossible to run overhead service wires directly from the pole to the building.

The process of producing electricity by transforming other forms of energy such as steam, heat or falling water. Also, the amount of electricity produced, expressed in kilowatt-hours (KWH) or megawatt-hours (MWH).

A producer of electricity, both literally and figuratively (can be gas or electric).

Generator, Backup
: A piece of equipment used to generate electricity in the event of an electrical outage.

A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of the earth.

Ground Conductor/Ground Rod:
The conductor of a circuit that provides safety from fire and electrical shock in cases of short circuits and other electrical problems. The conductor is physically attached to the earth and represents a zero volt potential, thus reducing the shock hazard to person if an electrical device fails or short-circuits.

Guy Wire:
A tensioned cable designed to add stability to a utility pole.

Horsepower (Hp):
A unit of power that describes machine strength. One Hp is 746 watts.

Hot Conductor:
The conductor that carries current from the power source to the equipment. For a complete circuit, the hot conductor requires a neutral conductor to carry the current back to the power source.

House Knob:
An attachment point that is securely mounted directly to the structure for the landing of the overhead electric service conductors.

1) A non-conductive material used on a conductor to separate conducting materials in a circuit. 2) The non-conductive material used in the manufacture of insulated cables.

An electrical connection between two points.

Kilowatt (kW):
The basic unit of customer electric power consumption at any point in time. One thousand watts.

Kilowatthour (kWh):
The basic unit of customer electric energy consumption, equivalent to an average of one kilowatt of power utilized for a period of one hour. One thousand watthours.

The customer’s electric power requirements in kilowatts, which must be supplied at various voltage levels on the Company’s distribution system.

Load Information Sheet:
The data sheet used to collect the electrical load and characteristics required by a premise.

Local Inspection Authority
: The agency responsible for the inspection of a customer’s electrical installations. The authority can be an agency of an incorporated City or Town or of the County, State or Federal Government. The Ameren Companies are not inspection authorities.

The process of finding and marking the locations of an underground facility.

The conduit installed between the meter socket and the weatherhead.

Megawatt (MW):
One million watts.

Megawatt hour (MWh):
One million watthours.

A device or devices used for measuring the kilowatthours, kilowatts and other characteristics of a customer’s electric consumption, as required by the applicable provisions of the customer’s rate.

Meter Socket, Multi-Meter:
The mounting device consisting of jaws, connectors, and enclosure for multiple socket type meters where no CT’s or PT’s are used. Commonly referred to as meter banks.

Meter Socket, Self Contained:
The mounting device consisting of jaws, connectors, and enclosure for socket type meters where no CT’s or PT’s are used.

Meter Socket, Transformer Rated:
The mounting device consisting of jaws, connectors, and enclosure for socket type meters where CT’s and/or PT’s are used.

Metering Instrument Transformer, Current (CT):
A device that precisely steps down the current from its primary current to a workable current that can be measured with conventional meters.

Metering Instrument Transformer, Potential (PT):
A device that precisely steps down the voltage from its primary voltage to a workable voltage that can be measured with conventional meters.

Missouri One Call:
The system established for making one telephone call to request locates for underground utilities. Commonly referred to as DIG RITE.

Missouri Public Service Commission (PSC):
See Commission.

Mobile/Modular Home:
A prefabricated home constructed to allow for movement from one location to another.

Refers to the Missouri Department of Transportation.

Multi-Tenant (Multi-Plex):
A multiple occupancy building with three or more Customers who each qualify for Residential rate or two or more Customers who qualify for a Non-Residential rate.

National Electrical Code. Generally speaking, this is the code document that governs building and premise wiring.

NEMA Code:
Refers to the National Electrical Manufacturers Association’s codes.

National Electrical Safety Code. Generally speaking, this is the code that governs electric and communication utilities.

Neutral Conductor:
The conductor that carries current back to the power source. It is always used with a hot conductor to complete a circuit.

Service supplied primarily for commercial, industrial, and/or temporary construction purposes, for individual meters.

Number of Wires:
The number of conductors that combine to assemble the service conductors.

The measure of electrical resistance, or impedance, in a circuit. One volt will cause one amp to flow through one ohm of resistance.

Open Wire Service:
May be three separate conductors, each attached to the building (2 hot conductors, 1 neutral).

Overhead Transformer:
A transformer that is mounted on a utility pole that is primarily used for overhead electrical service. Overhead transformers are available in both single and three phase units and single phase transformers can be banked together to provide three phase service.

Pad Mounted Transformer:
A transformer that is mounted on a pad (usually concrete) that is used for underground electrical service. Pad mounted transformers are available in single phase and three phase configurations.

Panel size:
The UL rating of the customer’s breaker/fuse panel.

A weather protected enclosure that connects the customer’s underground service to Ameren Missouri’s underground facilities.

A contiguous tract of land separated by nothing more than a highway, street, alley, or railroad right-of-way, where all buildings and/or electric consuming devices located thereon are owned or occupied by a single Customer or applicant for electric service, or where all electricity delivered thereto is utilized to supply one or more buildings and/or electrical loads which the Company considers as components of a unified operation.

Premise Number:
A unique number assigned to Premise.

Primary Point of Contact (PPC)
: The Ameren Missouri representative assigned to help you manage your request through the construction process.

Service supplied primarily for domestic purposes, to individual metered residences and apartments.

Right-of-Way (ROW):
A strip of land, granted by deed or easement, in which facilities are installed. Includes City, County and State owned roadway right-of-ways.

Service Conductors:
Refers to the conductors connecting a customer’s service point to the utilization voltage of the electric distribution system serving the customer.

Service Attachment:
The point at which the overhead electric service connects to the structure (house knob or mast).

Service Connections:
The connection between Ameren Missouri’s service conductors and the customer’s service entrance cables.

Service Drop:
The conductors connecting a customer’s service point to the utilization voltage of the electric distribution system serving the customer.

Service Entrance:
The part of the wiring from the connection at the outlets down through and including the breaker panel/ fuse box (except for the meter).

Service Entrance Cable:
The conductors that connect the service conductors (drop or lateral) to the service equipment of the building.

Service Equipment:
The necessary equipment, usually consisting of a circuit breaker or switch and fuses, and their accessories, located near the point of entrance of supply conductors to a building or other structure, or otherwise defined area, and intended to constitute the main control and means of cutoff of the supply.

Service Supply Type:
Indicates whether electric service is supplied by overhead or underground lines.

This implies a power supply or a load that uses only two wires for power. Some "grounded" single phase devices also have a third wire used only for a safety ground, but not connected to the electrical supply or load in any other way except for safety grounding.

The distance between two poles of a transmission or distribution line.

An individual’s Social Security Number or a company’s Federal Employer Identification Number.

A lot, tract, or parcel of land divided into two or more lots, plots, sites or other divisions for use for two or more new residential buildings or the land on which is constructed new multiple-occupancy residential buildings per a recorded plat.

Facility equipment that switches, changes, or regulates electric voltage.

Surge Protector:
An electrical device that protects equipment from a sudden, high fluctuation in the level of voltage normally flowing during a period of time.

Schedule of Ameren Missouri rates, charges, and General Rules and Regulations for providing electric service. Tariffs are available at, and are on file with the Missouri Public Service Commission.

Taxing Area:
The geographical area where premise is located and where taxes are paid. Generally speaking, taxing areas are jurisdiction boundaries such as cities or towns and may have inspection authority jurisdiction.

Temporary Service:
A service intended to be used for a limited period, such as for construction, purposes. The temporary meter structure will be removed after completion of the project.

Three Phase:
Multiple phase power supply or load that uses at least three wires where a different voltage phase from a common generator is carried between each pair of wires. The voltage level may be identical but the voltages will vary in phase relationship to each other by 120 degrees.

Transmission System:
An interconnected group of electric transmission lines and associated equipment for moving or transferring electric energy in bulk between points of supply and points at which it is transformed for delivery over the distribution system lines to consumers, or is delivered to other electric systems.

Triplex Service:
Three separate wires insulated and twisted around one another (2 hot wires, 1 neutral).

A residential building consisting of two units that share a common wall.

The measure of electrical pressure in a circuit. One volt of pressure is required to push one amp of current through a conductor with one ohm of resistance.

Water Heater, Conventional:
An appliance with a storage tank that supplies hot water for domestic or commercial purposes.

Water Heater, On-Demand:
An appliance that supplies hot water instantaneously based on flow for domestic or commercial purposes. Also known as a tankless water heater.

The amount of power used by an electrical device. Wattage can be calculated by multiplying voltage and amperage. Watts can be converted to amps with the calculation: watts divided by volts equals amps.

A weatherproof entry point for above-ground electrical wiring or telephone lines into a home or business. It typically tops a pipe-like conduit, and is shaped like a hood, with the face pointing down at an angle of at least 45°. A rubberized gasket makes for a tight seal against the wires. There is also a drip loop in the overhead wires which allows rainwater to collect and drip down before reaching the weatherhead.

Wire Gauge:
The diameter of a wire, measured in numbers.

Lighting Construction Frequently Asked Questions

Laptop Looking At Bill Happy
Find the answers to some frequently asked questions.

Call Before You Dig

Did you know you can disrupt utility service - and even put your life in danger - just by failing to have the locations of natural gas, electric and other underground utility lines clearly marked before you plant a new tree, set a fence post, or build a deck?

In Missouri, contact Missouri One Call, at 811 or 800.344.7483 (800.DIG.RITE).
Contacting Missouri One Call before you dig is not just smart - it’s the law. We recommend you visit Missouri One Call for full details about what you need to do before you dig.

Specifications for the Installation of Conduit System(s) for Streetlights

Find specifications for installation of direct buried conduit systems for streetlight cable.

Application Help

Main Request Application     MUST be completed for each service location.

TIP: The application can be saved and modified for additional requests at other locations.
Multiple Utility Service   A service application MUST be completed for each type of service requested at the same location. Example

TIP: If the billing party is different for any service or if the physical location for services is different - a new Main Request Application must be completed.
Non-Residential Service   Commercial, industrial, or non-residential buildings, barns or garages including temporary services for construction purposes, etc.
Residential Service   Single-family structures, multi-family structures, including apartments, condominiums, villas, lofts, etc., which are designed for the sole purpose of residential living.
Lighting Service
  Outdoor fixtures intended to light public areas, also known as dusk-to-dawn lighting. Fixtures are owned and operated by Ameren Missouri. All lights must be installed on an Ameren Missouri pole or customer-owned meter pole that is truck accessible. Installation charges may apply. Final determinations will be made by Ameren Missouri personnel.
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