Three-Phase Requirements

Note: Any member requesting three-phase service must consult with the engineering department at Sand Mountain Electric Cooperative before purchasing any equipment.

It is the intentions of SMEC to be reasonable in requirements and to work with all contractors, etc., toward a satisfactory and economical wiring installation.

It is the responsibility of anyone operating any electrical equipment that causes severe voltage fluctuations or other electrical interference on SMEC lines to immediately correct the problem at the member’s expense.

Three-phase motors, 10 hp to 75 hp, inclusive, must be provided with a current limiting starting device which will limit the starting current to 250 percent of full load current. This will permit the average normal current, normal torque NEMA design “B”, squirrel cage motor of 10 hp or less be started with magnetic full voltage starter. Most squirrel cage induction motors, 10 to 75 hp, inclusive, may be started with an autotransformer type starter connected to give starting voltage of 80 percent of full voltage.

Induction motors larger than 75 hp must be of the wound rotor type and shall be started with an increment type starter, which will limit the starting current to 150 percent of full load running current.

All three-phase motors must be protected by approved devices which will protect the motor from overload, single-phasing and under voltage and ground faults.

Note: All motors and installation, both single phase and three-phase must comply with national electric code.

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Click here to download an application for three-phase service