What makes up a kilowatt? What exactly is a degree day? Our glossary can help.

If you have additional questions or require additional assistance, e-mail media@mlgw.org or call (901) 528-4557.
 

Electric:

Base load: A consistent supply of electricity from the Tennessee Valley Authority. The load will increase during times of peak usage.

Capacity: The amount of electricity a particular electric line can safely carry.

Cooling degree days: The difference between 65 degrees and the actual average temperature for any given day. The theory is that if the temperature was a constant 65, no cooling would be necessary.

Conductor: A material that carries electricity.

Distribution lines: Power lines that carry electricity directly to individual customers.

Feeder lines: Electric lines originating at a substation that serve as the backbone of the Distribution system.

Fuel Cost Adjuster: Part of TVA rate structure that allows for fluctuations in market prices for materials such as coal that are used to create electricity.

Kilowatt (kW): 1,000 watts.

Lightning Arrester: Protective device that allows a path to ground for lightning strikes.

Substation: High voltage electricity comes from the TVA to the substation, where it is divided and the voltage lessened in order to be sent to customers.

Transformer: Electrical device that adjusts voltage to desired level.

Tennessee Valley Authority (TVA): The sole supplier of electricity to MLGW and 157 other utilities across the Tennessee Valley.

Watt: A unit of electrical power.
 

Natural Gas:

BTU (British Thermal Unit): The amount of heat necessary to raise one pound of water one degree Fahrenheit.

Carbon Monoxide: An odorless, colorless gas emitted as a result of the incomplete combustion of natural gas or other types of fuels.

Ccf (Hundred cubic feet): 100 cubic feet of natural gas. This is the measurement MLGW uses to bill customers.

Distribution system: Gas mains, services and equipment used to carry and control the supply of gas from the city gate station to the end-use customer.

Gas Gate Station: A point where natural gas comes to MLGW from major pipelines

Heating degree days: The difference between 65 degrees Fahrenheit and the actual average temperature for any given day. The theory is that if the temperature was a constant 65, no heating would be necessary.

LNG (Liquefied Natural Gas): Natural gas that has been converted to a liquid by reducing its temperature to -260 degrees Fahrenheit at atmospheric pressure. The liquid can be stored at 1/600 the volume of natural gas vapor. MLGW operates two LNG plants in Shelby County.

Odorant: A compound called Mercaptan that has a distinctive odor. MLGW adds odorant to natural gas to allow customers to detect leaks.

Market price: The current price for natural gas on the open commodity market. MLGW purchases only a fraction of its gas supply on the open market.

Meters: Device used to measure and record natural gas consumption.

Natural gas: an odorless, colorless gas made up primarily of methane. It has an average heating value of 1000 BTU's per one standard cubic foot of natural gas at 60 deg Fahrenheit and atmospheric conditions.

Pressure regulator: Device used to control the pressure in the natural gas system.

Purchased Cost Adjustment (PGA): The difference between MLGW's base rate and the actual cost of natural gas. All money collected through the PGA goes directly to pay for the supply of natural gas.

Therm: 100,000 British thermal units.

Transmission pipeline: Large underground pipelines, owned by gas transmission companies, that deliver natural gas over great distances.

Transmission system: Large underground pipelines and other equipment, owned by gas transmission companies, that deliver natural gas from a source of supply to one or more gas distribution companies or large volume customers. They typically differ from distribution systems in that they operate at higher pressures, are longer and the distance between connections is greater.
 

Water:

Aeration: Process used to force air into raw water and help remove iron and other minerals.

Aquifer: Natural underground reservoir which contains groundwater.

Artesian well: Natural underground reservoir which contains pressurized water capable of rising several hundred feet under its own force.

Chlorine: Chemical added at one part per million to kill bacteria that could contaminate the water after it leaves the pumping station.

Emergency shut-off valve: Located at every customer's home or business, used to stop the flow of water in an emergency.

Filter pool: Device consisting of eight layers of sand used to trap and remove particles from the water system.

Filtration: Second stage in the water treatment process which removes mineral particles from raw water.

Finished water: Water which has completed the treatment process and is either pumped directly into the system or stored for future use.

Flouride: Chemical added to water at one part per million to help prevent tooth decay.

Groundwater: Water contained in natural underground reservoirs.

Hundred cubic feet (ccf): Unit of measure used to define water consumption. One ccf equals 748 gallons.

Phosphate: Mineral added at one part per million to help prevent corrosion of water mains and customer pipes.

Pumping station: Facility where water is removed from ground, treated, stored and distributed for use.

Raw water: Water which has been pumped from the aquifer but has not completed the treatment process.

Reservoir: Natural or man-made storage area. May be above or below ground.

Service connection: Pipe measuring three-quarters of an inch to two inches in diameter, used to deliver water from the meter to individual customers. Customers are responsible for repairs.

Water main: Underground pipe measuring two inches to three feet in diameter, used to distribute water from pumping stations to customers' water meter.

Water meter: Device used to measure the amount of water consumed by a customer. Located in an underground meter box near the curb.

Well: Hole drilled to remove water from underground reservoirs.