Service Drop Wire

A service drop wire is the final overhead cable connecting utility power lines from a pole (or underground) to a customer's building, delivering electricity to the service head for entry into the home or business. These aluminum or copper cables, often duplex (two conductors), triplex (three conductors), or quadruplex (four conductors), are insulated for outdoor conditions and come in various sizes to handle different electrical loads. 

Key Characteristics & Types of Service Drop Wire

Purpose: To provide the final electrical connection from the utility's distribution network to the consumer's premises.

Conductors: Typically made from aluminum or copper, often with a bare neutral messenger wire.

Service Drop Wire Specifications

Materials: Modern service drops primarily use aluminum (e.g., 1350-H19 series) because it is lightweight and cost-effective. Older installations may still feature copper.

Insulation: Typically made of XLPE (Cross-Linked Polyethylene) for high heat resistance (90°C) or PE (Polyethylene) for standard moisture resistance (75°C).

Neutral Messenger: Often reinforced with ACSR (Aluminum Conductor Steel Reinforced) to provide the structural strength needed to support the cable's weight over long spans. 

Standard Sizing (Aluminum)

The required gauge depends on the electrical load (ampacity) of the building: 

Service Ampacity Recommended Aluminum Wire Size

100A 2 AWG

150A 2/0 AWG

200A 4/0 AWG

Service Drop Wire Common Types

Service drop wires are categorized by the number of conductors bundled together: 

Duplex: Two conductors (one insulated "hot" phase and one bare "neutral" messenger). Used for single-phase systems like street lighting or temporary construction power.

Triplex: Three conductors (two insulated phases and one bare neutral). This is the standard for residential homes and small commercial buildings to provide 120/240V power.

Quadruplex: Four conductors (three insulated phases and one neutral). Used for industrial facilities or apartment complexes requiring three-phase power. 

Service Drop Wire Function

From Pole to Weatherhead: The cable runs from the utility pole to the "weatherhead," a protective fitting at the building's exterior.

To Service Entrance: From the weatherhead, it connects to the main service entrance conductors that go into the electrical panel. 

Variations:

While typically overhead, similar cables can also be used underground as underground service-entrance (USE) cable.