page_title: Service drop
section_title: North American
hierarchical_section_title: Service drop / Residential / North American
caption_attribution_description: English: An electrical service drop, where electric power is supplied from overhead power lines to a residence in Mount Vernon, Washington, USA. This provides the 110V/240V "split phase" power standard in North America. The "triplex" cable from the utility pole (left) consists of two lines each carrying 120 volts, and an uninsulated ground cable. The cable provides 120 V power for loads connected between one of the phase cables and ground, and 240 V power to loads connected between the two phase cables. The cable enters a conduit through a weatherhead, and drops down to the electric meter, then passes through the wall of the house to the service panel, where it is connected to the home power wiring.
context_page_description: In electric power distribution, a service drop is an overhead electrical line running from a utility pole, to a customer's building or other premises. It is the point where electric utilities provide power to their customers. The customer connection to an underground distribution system is usually called a "service lateral". Conductors of a service drop or lateral are usually owned and maintained by the utility company, but some industrial drops are installed and owned by the customer.
  At the customer's premises, the wires usually enter the building through a weatherhead that protects against entry of rain and snow, and drop down through conduit to an electric meter which measures and records the power used for billing purposes, then enters the main service panel. The utility's portion of the system ends, and the customer's wiring begins, at the output socket of the electric meter. The service panel will contain a "main" fuse or circuit breaker, which controls all of the electric current entering the building at once, and a number of smaller fuses/breakers, which protect individual branch circuits.
context_section_description: In North America , the 120/240 V split phase system is used for residential service drops. A pole-mounted distribution transformer usually provides power for one or two residences. The service drop is made up of two 120 V lines and a neutral line. When these lines are insulated and twisted together, they are referred to as a triplex cable which may contain a supporting messenger cable in the middle of the neutral conductor to provide strength for long spans. The neutral line from the pole is connected to a ground near the service panel; often a conductive rod driven into the earth. The service drop provides the building with two 120 V lines of opposite phase, so 240 V can be obtained by connecting a load between the two 120 V conductors, while 120 V loads are connected between either of the two 120 V lines and the neutral line. 240 V circuits are used for high-demand devices, such as air conditioners, water heaters, clothes dryers, ovens and boilers, while 120 V circuits are used for lighter loads such as lighting and ordinary small appliance outlets.
caption: A 240/120 V split-phase service drop providing power to a residence in USA. The three wires from the utility pole enter through a weatherhead (top) into a vertical conduit, which routes them to the electric meter (bottom). From there they pass through the wall of the house to the electric panel inside.
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