A wire harness contains three main components: wires, wiring harness connectors, and terminals. Wire harnesses, or wire assemblies, consist of varied wires or cables organized together that can be customized for a multitude of applications. Harnesses protect wires from environmental conditions like friction, temperature, or moisture.

Depending on the intended environment, there are multiple terminal and wiring connector types available. Wire harnesses are commonly used in electronics, aerospace, medical, automotive, or military hardware applications.

In terms of the third component, wire harnesses may be used to protect and organize nearly any wire type, such as discrete (lead) wires, multi-conductors, solid and stranded cables, hook-up, and more. This blog will explore the various types of connectors and terminals available.

Wire Harness Connectors

Wire harness connectors provide an uninterrupted electronic signal between a wire harness and a power source. Plugs are typically male, while jacks are usually female. Other than that, connectors may differ broadly in size, shape, and dimension as needed by the intended application.

Wire Harness Connector Types

wiring harness connectors and terminalsDetermining the appropriate type of connector depends on multiple performance factors, such as mating type, insulation needs, power contacts, and signal contacts. Configurations may also vary, with options including wire-to-wire, board-to-board, or board-to-wire. Connectors come in multiple designs, with 2-, 3- or 4-pin connectors being standard. When selecting a connector, it is crucial to know the necessary:

  • Current rating
  • Circuit density and size
  • Engagement force
  • Wire size
  • Operating voltage
  • Agency approvals
  • Price per circuit

Wire Harness Terminals

Wiring harness terminals are the components in which the wire ends or where it will be connected to other components. Similar to wiring harness connectors, the type of terminal needed depends on the intended application and can vary in shape, size, and insulation needs. Non-insulated terminals are a more cost-effective choice when protection from temperature, moisture, or environmental conditions is unnecessary.

Wire Harness Terminals Types

There are a variety of wire harness terminal types to choose from:

  • Ring terminals are round-ended, allowing screws or studs to be attached. They come in various sizes, can be insulated, and are crimped or soldered to wires.
  • Spade terminals—also called fork terminals due to their shape—are open-ended for easy attachment and removal in harness applications with tight space requirements. They are available with or without insulation.
  • Hook terminals are simplistic, open-ended terminals similar to spade terminals. They are durable and can be insulated or non-insulated.
  • Quick-disconnect terminals, as their name implies, are designed for rapid disconnect in automotive, industrial and consumer applications.
  • Bullet terminals provide secure connections between male and open-ended round female connectors. These terminals are intended to prevent corrosion and other damage from dangerous materials.
  • Butt terminals guard against abrasion, moisture, and corrosion. They can terminate single or multiple wires and can be used to easily extend wires by installing them on the open ends of connectors.
  • Flagged terminals are ideal in tight spaces as they have a designed 90 degree bend like a flag on a pole. They provide easy connections and can be insulated or non-insulated.

Importance of Wire Harness Design

Wire harnesses must be carefully designed with specific application needs in mind, so the wire harness design process is extremely customizable. Many wire harnesses need to be concealed in walls, boxes, or otherwise constrained spaces. For safety and function, high quality design is crucial. Environmental elements must be taken into consideration in wire harness designs, as demonstrated by the various components listed above. Aside from temperature, friction, and moisture, electrical interference and radiation can also cause potential problems for harnesses.

Harnesses must fit in an organized fashion in their locations and may need appropriate casings depending on application. Correct terminals and connectors are vital to ensure harnesses are protected and appropriately routed. Wire ends, strip lengths, voltage and current requirements, sheath materials, and wire tolerance all need to be precisely measured and accounted for in the design of the wire harness.

Working with PCMI

Well-designed wire harnesses with the correct terminals and connectors won’t require replacements and will extend the life of the wires. To ensure a well-designed harness, Precision Manufacturing Company, Inc. (PCMI) creates custom kits and high quality products and components. For more information about wire harnesses and components for your application, please request a quote.