sleeve
A double tube of copper into which the ends of bare wires are pushed so that when the tube is twisted an electrical connection is made. The joint thus made is called a McIntire joint.
sleeve: twisted-wire connector that needs no solder
A sleeve is a short length of soft copper tubing, typically 0.5 to 2 inches long, used to join the stripped ends of two bare conductors. The two wire ends are inserted into opposite ends of the sleeve, and the sleeve is then twisted under tension, compressing the copper around both conductors and forming a gas-tight, low-resistance joint without solder or flux.
The most common form in power utility work is the McIntire joint, named after its developer. The sleeve is rotated by hand or with a wrench while the wires are held under slight tension, typically achieved by a hand-held tool or by suspending weight. As the copper deforms, it creates mechanical grip and metal-to-metal contact that conducts electricity reliably. The joint's strength and conductivity depend on proper alignment of the wires and sufficient rotation to fully compress the sleeve.
When and where sleeves are used
Sleeves appear most often in overhead transmission and distribution work, where bare copper or aluminum conductors must be spliced without access to power tools or heat sources. They are practical for field repairs and temporary connections. However, they have largely been displaced by compression connectors and mechanical terminals in modern installations, which are faster and less dependent on operator technique. Sleeves remain common in legacy systems and in situations where tools are limited.
The quality of a sleeve joint depends heavily on wire cleanliness and operator skill. Oxidized copper, misaligned wires, or insufficient rotation produces a weak connection with high resistance and risk of heating or corrosion. Copper sleeves are self-annealing after twisting, which can make them brittle; joints on suspension lines may crack over time from vibration. The method also requires clear access and enough physical strength to apply proper tension.
Sleeves are sized to match the conductor diameter and material (copper sleeves for copper wire, aluminum for aluminum). The copper tube stock is softer than the conductors it joins, so it deforms preferentially and clamps them firmly. Cost is low compared to crimped or soldered joints, but the trade-off is slower installation and higher variability in connection quality.