What is the purpose of drain wire in cable?

Drain wires are used in cables in conjunction with a metallic shield to ensure effective grounding. The drain wire serves to complete an electrical circuit from the shield and carry unwanted electrical noise to ground away from the circuit.

What should you do with the drain wire of a screened cable?

The wire remains in contact with the metallic side of the shielding tape all through the body of the cable. That places the drain wire in an ideal position to connect a shielded cable to its ground terminal.

What is USB drain wire?

That is the drain wire that helps carry charge off of the foil jacket and carries more current than the foil can. It is part of the shield/ground of the cable.

What is the purpose of shielded wire?

Shielded cable is necessary to reduce and prevent all the effects of EMI and the other hazards found in busy, industrial workplaces. The shield reflects energy and grounds electrical noise by surrounding the power-carrying conductors or inner signals.

What is the purpose of screen wire used in audio cables?

The screen is often directly placed over the insulated cores or pairs inside the cable. The purpose of a screen is to reduce signal trying to escape from the cable while also preventing external electrical noise and interference from affecting the signal the cable is carrying.

Why is the drain wire connected at one end only?

The original reason for only grounding on one end was to eliminate “ground loops” or common mode hum, on audio circuits and the like. The cable shield works best when the signal lines are completely surrounded by a conductive “tunnel” that is completely at ground potential.

Where does cable shield connect?

The best way to wire shielded cables for screening is to ground the shield at both ends of the cable. Traditionally there existed a rule of thumb to ground only the source end of the shield to avoid ground loops. Best practice is to ground at both ends, but there is a possibility of ground loops.

What is shielding and grounding?

Grounding means to connect electrical equipment to a common reference ground or earth. Shielding is used both for immunity (protecting against external interference) and emission (preventing interference to be radiated).