Copper Braid and Braided Straps: Flexible Bonding, Earthing and Vibration Duty

A solid copper strap is stiff. Every thermal cycle and every vibration event turns that stiffness into stress at the bolted ends — and stress at a bolted joint is exactly where connections loosen and resistance climbs. Copper braid solves this by construction: thousands of fine strands woven into a flat or round section that flexes freely while carrying full current.

Where braid beats solid bar

• Vibration: machine frames, generator sets, rail and mobile equipment — anywhere the two ends move relative to each other.
• Thermal cycling: busbar expansion joints, transformer connections, switchgear links that heat and cool with load.
• Movement paths: sliding doors, hinged panels and draw-out racks that need a continuous bond across a moving interface.
• Earthing bonds: equipment-to-structure bonds where the strap must absorb settlement and movement without loading the joint.

Forms: flat strap, round braid, braided tape

Flat braided straps — our copper earth straps with tinned, bolt-hole ends — are the standard bonding and earthing form: wide, thin, easy to bolt, and they lie flat against surfaces. Round braided conductors (RRCB style) suit tight bends and confined routing. Braided tapes (FSSB, MBJ/BJ, CPL families) are wider, thinner sections used for large-area bonds and sliding interfaces, in copper or copper-clad stainless for corrosive sites.

Finish: tinned, bare or nickel-plated

Bare copper is the cheapest and the most conductive, but it oxidizes and discolors in humid or sulphur-bearing air. Tinned copper — the default for our grounding braid — solders and bolts well and resists oxidation, which is why tinned ends appear on nearly every earth strap we ship. Nickel plating goes on where temperature or corrosion exceeds what tin tolerates. Specify the finish from the environment, and keep the termination finish compatible with the pad it bolts to.

Terminations decide the life of the joint

Braid fails at its ends, not in its length. The reliable options are tinned solid ends drilled for bolts (as on our earth straps), crimped or welded lugs (PB connector family), or integral pressed terminals. What kills braids is clamping loose strands under a bolt: strands creep, contact area shrinks, resistance rises and the joint heats. Always terminate on a solid, tinned end section sized for the bolt.

Sizing and current

Braid cross-section is quoted in mm² like any conductor, but its current capacity depends on installation: free air, enclosed, duty cycle and whether the load is continuous or fault-rated. For earthing and bonding duty the cross-section is usually set by the standard or the fault-current calculation, not by continuous load. Send us the duty — continuous current, fault current and duration, or the applicable standard — and we return the section and length.

Specification checklist

• Form: flat strap, round braid or braided tape for the routing
• Finish: tinned (default), bare or nickel-plated per environment
• Termination: tinned bolt-hole ends, crimped lugs or pressed terminals
• Cross-section from the fault/bonding calculation, not from continuous load alone
• Length with slack for the expected movement — braid must never be installed taut
• Compatible bolt hardware and contact paste where dissimilar metals meet

Frequently asked questions

Can braid replace flexible cable for power?

Uninsulated braid is a bonding and earthing conductor, not an insulated power cable. Where insulation is required, use insulated braided conductor tape families or cable.

Why do earth straps have tinned ends but bare middles?

The ends are where oxidation hurts the joint; tinning the termination zone protects the contact while keeping cost down. Fully tinned straps are available for corrosive sites.