Crimpers are specialized tools used to connect wires to create a permanent electrical connection, or splice, through applied pressure. To make a crimp, the ends of the wires are inserted into a sleeve or compression connector. It is then squeezed with sufficient pressure from the tool to deform the connector, pressing it tightly enough against the wires (and thus reducing the resistance to the flow of electricity between the wires) to make the connection a nonreversible one.

By using the proper type and size of compression connector for the wire, an installer cuts back an amount of insulation as specified in the installation instructions that come with the connectors. Because all components have to be approved to work together to earn or maintain the UL rating, it is necessary to verify that the connector is approved to work with the type of wire to be connected and that the crimper tool is approved to work with the connectors. Combinations of materials also need to be compatible: while copper cable can be installed in rated copper compression connectors or in appropriately rated aluminum compression connectors, aluminum wire cannot be installed in a copper compression connector. To help ensure good connections with every crimp, strands of wire or cable (new or already installed) and the connectors should be dirt-free and not show any signs of corrosion.

A crimp can be successfully achieved with manual muscle-powered crimpers, hand-operated or foot-operated hydraulic crimpers, line voltage-assisted hydraulic crimpers, or battery assisted hydraulic crimpers.

For situations where many crimps are required in a workday or where crimps are called for on large conductors, the assist afforded by hydraulic crimpers may be very welcome. Hydraulic-assisted crimpers reduce the force the tool operator needs to exert and may reduce risk of muscle strain or other repetitive motion injuries.

Crimpers are classified as either die or dieless. With die crimpers, a die set is inserted into the tool. Dies, connectors and wires are certified to work together. The connector and the die set are, typically, color coded, embossed, or otherwise visibly marked to help identify that they match, making it easier to select the right die from a possibly large number of die sets that could work with a given crimper. Some manual die crimpers have a built-in multi-nested die wheel that the operator spins to select the proper die for the connector. Die wheels help preclude inadvertent loss of any die.

While die crimpers require distinct sets of dies for each connector/wire size, die-less crimpers are self-contained units that can crimp any matching connector to a wire within the unit’s range. The tools, themselves, are adjustable to accommodate different-size connectors.

Tools discussed below are representative of manufacturer offerings. Many companies offer a full line of crimpers.

Hand-held crimpers

With muscle-powered hand-held crimpers, all the energy to make the crimp comes from the electrician, who controls the amount of force exerted for each crimp. Some units come with long handles or handle extenders to increase the leverage for the installer. More leverage translates into less effort. Depending upon the number of crimps and their size, a muscle-powered crimper could suffice for a day’s crimps.

Penn-Union TDM-500 Dieless Mechanical Compression Tool features adjustable jaws that accommodate a wide range of wire, #8-500 MCM Al or CU. The all-steel tool, with precision-machined indentor, component parts and body, sports a special extendable-length handle design that, notes the company, provides increased leverage. A twist-lock holds the rubber-grip handle in place, securely, at any length. At 500 MCM, the tool requires less handle load than conventional 250 MCM tools require at 250 MCM. The narrow head design facilitates use of the tool in confined areas. Two calibrated index plates on the side of the tool, one for aluminum and the other for copper, provide easy-to-read settings. The unit weighs in at less than 10 pounds, affording tool maneuvering with minimal user fatigue.

Panduit Contour Crimp CT-1550 Terminal Crimping Tools is designed for the installation of PAN-TERM terminals, disconnects, wire joints and splices from #22 to #10 AWG. The unit has two different die sets built in—one set for wires sized 12-10, the other for wires sized 22-14. The ergonomically designed handle, engineered to accommodate all-size hands and featuring cushioned non-slip grip material and contoured finger grips, facilitates two-handed crimping, to further reduce the handle effort needed to make a crimp, notes the company. A special locator ensures proper location of the terminal in the crimp pocket and retains the proper part orientation throughout each crimp. The tool features a built-in ratchet device that is releasable for added safety. A controlled cycle mechanism, governing the handle sweep to make certain the handles are brought together completely before they release and the dies open, ensures a complete, uniform crimp each time.

Klein Tools Compound-Action Ratching Crimper Cat. No. T1710 crimps 22-10 AWG insulated terminals to meet or exceed MIL-SPEC pull-out test. The built-in ratchet, with safety release, ensures reliable, uniform crimps. The compound lever-action of the narrow-span 9-inch long handles puts more crimping power into each squeeze, notes the company. The jaws will not open until the crimp is completed. Upon crimp completion, the jaws and handle, which sports a plastic comfort grip, automatically release. The tool’s crimp cavities are fully machined in high-carbon steel, and then heat treated to meet industry standards and provide the level of performance required for most stringent commercial applications.

Suitable for smaller wires, Gardner Bender Multi-Tool Stripper & Cutter GS-70 crimps 10-22 AWG insulated and non-insulated wire terminals. The unit, which also crimps coaxial cable “F” connectors, strips 10-22 AWG solid or 12-24 AWG stranded copper or aluminum wire, and cuts and rethreads bolt sizes 4-40, 5-40, 6-32, 8-32, 10-24 and 10-32. The laser etched markings are permanent and will not rub off. The tool, which has a curved cutting blade and textured handles for no-slip grip, is configured with a tapered pliers nose, for longer reach and for working in tight areas.

Hydraulic crimpers

Hydraulic crimpers may be hand-held, hand-operated compression models, where the hydraulic fluid is housed within the tool itself and the worker pumps the handle to apply pressure to the fluid; remote-powered, with the crimping head attached to a flexible hydraulic hose that runs to a pump that applies pressure to the hydraulic fluid within the hose (the pump being hand- or foot-activated or electrically powered); and battery-powered hand-held, where the battery housed on the unit provides the power to apply pressure onto the hydraulic fluid within the unit to create the pressure needed for the crimp.

With a hand-held hydraulic crimper, the electrician positions the connector between the jaws and pumps the tool until the jaws crimp the connector to the proper pressure. With a remote pump hydraulic-assisted crimper, the pump may be portable, suitable for shoulder strap, waistband suspension or placement on the ground, or may be designed specifically to sit on the ground, reducing the weight the worker has to carry and providing, potentially, easy maneuverability.

Battery-powered crimpers are efficient when the wire size or the number of crimps needed warrants power-assisted crimping and are, regardless of the > number of crimps needed, very handy for crimping large-size wires when electric power is not readily > available at the work site. Requiring minimal set-up, they are, typically, easy to operate—the compression cycle is pre-set, controlled by the tool rather than tool operator, and there is often either automatic retraction or an audible signal when the crimp is complete.

The new BCT500-HS battery-powered crimping tool, from FCI Burndy Electrical, provides six tons of compressive force in a compact unit that sports an ergonomic handle design and a variable-speed trigger that allows the operator flexibility in the speed of ram advance. The 8.36-pound tool, featuring an eight-second crimp time, is operable with one hand, leaving the other free to manipulate the connector and the conductor. The ram holds position when the trigger is released, providing the user with the ability to hold the connector between dies and check for proper alignment before proceeding with the crimping action. The stainless-steel latch-style head, with 180 degree rotation, allows interference-free closure for installation applications on #8-500 kcmil copper and #8-350 kcmil aluminum lugs and splices. Die selection includes all Burndy “W” and W-VT” style dies, which seat in the permanent “D3” crimping groove. The tool comes with a metal case, two batteries and a charger.

Greenlee Textron EK1240-11 12-ton battery-powered crimping tool, with a 1.65-inch opening for industry “U” type dies, runs on a 12V 2.0 Ah (amp hour) battery that can do a crimp in as little as seven seconds and that provides up to 35 crimps per charge. The tool, which crimps up to 750 KCMIL copper or aluminum cable, features a 360- degree rotating head, for access where maneuvering space is limited, and automatic ram retraction when the crimp cycle is complete. A two-speed pump reduces cycle time, allowing the operator to utilize a fast speed when the ram is running up to contact the connector and then shift to a slower speed (with more power) to finish the crimp. The head, designed to achieve high durability at a relatively low weight and tested to 50,000 crimp cycles, can also fit on the company’s 12-ton remote-powered crimper and hand-operated hydraulic crimper. The tool comes with a one-hour charger, two batteries and a carrying case.

ILSCO IDTB-6 battery-powered 6.2-ton dieless crimp tool accommodates a conductor range of 750 MCM-#6 Al/Cu. Featuring a flip-top head that rotates 360 degrees for access in tight spaces, the IDTB-6 uses a four-point indent crimp, compressing connectors from four directions simultaneously. A two-speed pump advances the ram quickly to begin the crimp, which saves time. The ram retracts once the crimp is complete. A pull-out pin on the head opens for easy removal of the head from the connector after the crimp is completed. An angled pistol grip reduces hand strain when performing repetitive crimps. The 10.8 pounds weight of the tool is light enough for one-hand use, so the installer can position, adjust, and hold the connector with the other hand before crimping. The tool comes with two 12-volt 1.7-Ah batteries (each providing up to 80 crimps per charge), a durable steel carrying case and an AC charger.

Thomas & Betts handheld Color-Keyed Battpac LT 6-Ton Compression Tool is a battery-powered unit suitable for use with copper connectors up to 500 MCM and aluminum connectors up to 350 MCM. The lightweight unit (8 pounds including the rechargeable battery), featuring a vibration-free crimping cycle for smooth installations, allows single-handed operation, leaving the second hand to control the operation and position the connector. The tool, which has an ergonomically designed center-grip handle, can complete over 125 crimps with a 4/0 cable on a single charge. The 180-degree rotating crimping head facilitates access in confined or hard-to-reach work spaces. The unit, with the power switch protected against accidental operation and a fully accessible pressure release button right underneath it, also sports a battery condition display and a maximum-pressure relief valve that ensures correct crimping. The kit, TBM62500BSCR, includes the tool, two 14.4v 2.0 Ah Ni-Cad batteries, a charger, shoulder and wrist straps, die sets up to 500 MCM size and a carrying case.

Anderson VC6-350BP Tonnage Versa Crimp nominal 6.2-ton battery powered hydraulic compression tool, by Hubbell Power SystemsOperating on a fixed-pressure principle, the hand operated tool features three self-contained crimping nibs that advance, in a continuous action, from the largest opening to the smallest, until the preset hydraulic relief value senses that the proper force has been applied to the crimp. At that point, the value “pops off,” signaling the crimp is complete and releasing pressure in the tool. Weighing 9½ pounds, the tool, which features 180-degree head rotation and single-handed operation, runs on a 14.4V rechargeable battery. The tool comes in a kit with two batteries, a 15-minute AC charger, shoulder strap, plastic carrying case and shipping case, and “O” and “D” nib/nest. is a dieless, range-taking crimper suitable for conductor ranges of #8 Str.-350 kcmil Al and #8 Sol.-300 kcmil Cu.

Huskie Tools, Inc. REC 3510 ROBO CRIMP is a 12-ton battery-powered compression tool that accepts all “U” type dies on the market. The 1.65-inch jaw opening automatically accepts mid-span copper and aluminum sleeves and cables up to 750 MCM. The output pressure can be adjusted, within a broad range, via a bypass port at the top of the tool. When the sleeves are compressed, they can be removed through the jaw. An audible beep indicates that 12-ton pressure is achieved. The tool features one-finger trigger operation that, says the company, minimizes fatigue and muscle-related strains. The tool comes in a kit that includes two batteries, a 25-minute charger, a carrying strap and a carrying case. EC

The FELDMANS write for various magazines and Web sites. They can be reached at or 914.238.6272.