Glossary of electric industry, energy & cooperative terms

M

Mantel
The shelf above a fireplace. Also used in referring to the decorative trim around a fireplace opening.

Margins
The difference between the net system generating capability and system maximum demand requirements including net scheduled firm transfers with other systems.

Margin-Cost Pricing
A method of determining the selling price of a commodity when the fixed costs are paid by units already sold so that the next units can be sold for less.

Market-Based Pricing
Electric service prices determined in an open market system of supply and demand under which the price is set solely by agreement as to what a buyer will pay and a seller will accept. Such prices could recover less or more than full costs, depending upon what the buyer and seller see as their relevant opportunities and risks.

Market Clearing Price
The price at which supply equals demand for the Day Ahead and/or Hour Ahead Markets.

Masonry
Stone, brick, concrete, hollow-tile, concrete-block, gypsum-block or other similar building units or materials or a combination of the same, bonded together with mortar to form a wall, pier, buttress or similar mass.

Mastic
A pasty material used as a cement (as for setting tile) or a protective coating (as for thermal insulation or waterproofing).

Maximum Demand
The greatest of all demands of the load that has occurred within a specified period of time.

Mcf
One thousand cubic feet.

Megawatt (MW)
A unit of electric real power equal to 1,000 kilowatts or 1,000,000 watts.

Megawatt-Hour (Mwh)
A megawatt-hour is a unit of energy equal to 1,000 kilowatt-hours.

Meter
A device for measuring levels and volumes of customer’s electricity use.

Mill
One tenth of a cent or one thousandth of a dollar.

Minimum Charge
A provision in a rate schedule stating that a customer’s bill cannot fall below a specified level. For example, the electric energy charge may be 10 cents per kilowatt-hour (kwh), with a $1 minimum charge. In this case, a customer would be billed for $1 if usage were anywhere between zero and 10 kwh.

A minimum charge differs from a customer charge in that charges for energy consumed are added to a customer charge, whereas a minimum charge ensures that the bill for energy consumed does not fall below a certain amount, even if little or no energy is consumed. A minimum charge is similar to a customer charge because it is designed to recover fixed costs of services such as meter reading, billing and facilities maintenance. Although this charge does not generally recover the full cost of these services, it does give the customer a price signal that these costs do exist.

MMcf
One million cubic feet.

Molding
A wood strip having a curved or projecting surface used for decorative purposes.

Monopoly
The situation of an individual or corporation owning or controlling so large a part of the market supply of output of a given commodity or service that competition is stifled and freedom of commerce restricted, giving the monopoly control over prices. To prevent the abuses that may result from this concentration of economic power, monopolies are generally forbidden by law.

Utilities, including railroads, telephone companies and power companies, tend to gravitate naturally toward a monopolistic structure. They are natural monopolies – enterprises that can, through economies of scale, produce more of a particular product or service at a lower cost by operating near full capacity on a large scale. If two or more utilities were to compete in the same area for the opportunity to serve the same customers, expensive and duplicative systems would have to be built. Because economies of scale allow a single public utility to provide economic advantages to its service area, utilities (natural monopolies) are permitted to exist subject to strict governmental regulations.

Through regulation, society ensures that good, safe and reliable services are provided to all customers at reasonable, non-discriminatory prices. Regulators determine a reasonable cost of doing business, including a reasonable return on investment, and set rates designed to recover those costs. Utilities are not guaranteed a rate of return found reasonable by their regulators. Rather, they must keep their expenditures within the allowances provided by these commissions if they are to have a reasonable opportunity to earn that return.

Mullion
A vertical bar or divider in the frame between windows, doors or other openings.

Municipal Utility
An electric utility system owned and operated by a municipality that generates electricity and/or purchases electricity at wholesale for distribution to retail customers (residential, commercial, and industrial). Ohio's municipal electric utilities take their authority from the Ohio Constitution and are locally regulated by the municipality's governing body (city or village council).

Municipal electric utilities today far outnumber investor-owned facilities. The ration is approximately 9 to 1 (2,000 to 225), not including organizations like rural electric cooperatives and public power districts. There are 33 municipalities in Florida that own and operate electric utility systems. These systems are owned by the citizens of the city in which they are located and are regulated by the regulatory authorities in the municipality through their city councils or commissions.

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Page last updated: Friday, March 5, 2010