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The slowly varying portion of demand is known as the base load and is generally served by large facilities with constant operating costs, termed firm power. It is easy to understand, therefore, that whereas the resistance of a wire can be almost constant, its ampacity depends on the temperature and some other working conditions, and it cannot be a constant. Specific resistance: Same as resistivity: the electric resistance of a specific size (based on the measurement system) of a metal or material. 100, provided the same sized conductors are used in both cases. And since conductance is proportional to cross-sectional area, resistive power loss is only reduced proportionally with increasing cross-sectional area, providing a much smaller benefit than the squared reduction provided by multiplying the voltage. It was powered by two Siemens & Halske alternators rated 30 hp (22 kW), 2 kV at 120 Hz and used 19 km of cables and 200 parallel-connected 2 kV to 20 V step-down transformers provided with a closed magnetic circuit, one for each lamp. It also featured Siemens alternators and 2.4 kV to 100 V step-down transformers - one per user - with shunt-connected primaries.

Voltage was stepped down to 100 volts using the Stanley transformer to power incandescent lamps at 23 businesses over 4,000 feet (1,200 m). It was powered by a 2 kV, 130 Hz Siemens & Halske alternator and featured several Gaulard transformers with primary windings connected in series, which fed incandescent lamps. In the United States, power transmission is, variously, 230 kV to 500 kV, with less than 230 kV or more than 500 kV as exceptions. Local sources (even if more expensive and infrequently used) can protect the power supply from weather and other disasters that can disconnect distant suppliers. Hydro and wind sources cannot be moved closer to big cities, and solar costs are lowest in remote areas where local power needs are nominal. Long underground AC cables have significant capacitance, which reduces their ability to provide useful power beyond 50 miles (80 kilometres). In some metropolitan areas, cables are enclosed by metal pipe and insulated with dielectric fluid (usually an oil) that is either static or circulated via pumps. If an electric fault damages the pipe and leaks dielectric, liquid nitrogen is used to freeze portions of the pipe to enable draining and repair.

The Brockville plant became known as GTE Automatic Electric. This device is a Microtel Enterphone, manufactured in the Brockville plant in February, 1985. The Enterphone was designed for apartment entry control, and unlike other systems on the market which required an intercom in each apartment and separate wiring for the intercom system, the Enterphone placed a call to the tenant's regular telephone, saving considerable cost for the apartment owner. When Microtel wound up operations, the Brockville plant then was sold on January 24, 1990 to Nortel then becoming known as Brock Telecom. When the battery is needed, then it is assembled (e.g., by adding electrolyte); once assembled, what is electric cable the battery is charged and ready to work. A DC link therefore stabilizes the AC grid at either end, since power flow and phase angle can then be controlled independently. Costs can be prohibitive for transmission lines, but high capacity, long distance super grid transmission network costs could be recovered with modest usage fees.

The transmission network is usually administered on a regional basis by an entity such as a regional transmission organization or transmission system operator. The first commercial AC distribution system entered service in 1885 in via dei Cerchi, Rome, Italy, for public lighting. The first long distance AC line was 34 kilometres (21 miles) long, built for the 1884 International Exhibition of Electricity in Turin, Italy. A few months later it was followed by the first British AC system, serving Grosvenor Gallery. In what became a universal system, these technological differences were temporarily bridged via the rotary converters and motor-generators that allowed the legacy systems to connect to the AC grid. Wind turbines, vehicle-to-grid, virtual power plants, and other locally distributed storage and generation systems can interact with the grid to improve system operation. Thus, generators were sited near their loads, a practice that later became known as distributed generation using large numbers of small generators. Interconnection of local generation plants and small distribution networks was spurred by World War I, when large electrical generating plants were built by governments to power munitions factories.