Article
The weakest links in any electrical distribution system are those 
locations where connections are made. Secure tap, terminal and splice 
connections are critical to a system’s safety and reliability. 
Electrical contractors have a number of options when it comes to the 
connectors they use in these applications, with mechanical- and 
compression-style connectors being the most common.

Connection Basics: Understanding Mechanical and Compression Connectors

Chuck Ross
The weakest links in any electrical distribution system are those locations where connections are made. Secure tap, terminal and splice connections are critical to a system’s safety and reliability. Electrical contractors have a number of options when it comes to the connectors they use in these applications, with mechanical- and compression style connectors being the most common. Each of these products has advantages that make them useful in particular settings, but neither approach is right for every electrical job. Understanding how these products work, along with their strengths and weaknesses, can help contractors make the right choice for the project at hand.

These names can seem a tad confusing, since both of these connector types use mechanical force to create connections between conductors. With mechanical connectors, the force is applied and maintained by a set-screw or bolt that’s adjusted to a manufacturer-recommended torque. With compression connectors, a special crimping tool equipped with a die that matches the size of the conductors squeezes down to bond conductors and connector together.

Mechanical connectors are certainly easier to install, using screwdrivers or wrenches found in any contractor’s toolbox. Plus, the same connector can be used with a range of conductor sizes – an advantage manufacturers call “range taking.” They’re also reusable in situations where rewiring is required. But that flexibility puts them at a disadvantage in high-tension applications, where conductors could work themselves loose, over time.  

Installing compression connectors is a more complicated process. While the individual connectors are inexpensive, the equipment required to install them can be pricy. Smaller projects might only call for an easily affordable hand crimper. However, larger projects will require heavy-duty electric crimpers, along with an inventory of dies sized for specific conductor gauges. On the plus side, though, when performed correctly, crimped connections are permanent and irreversible, so they won’t pull apart under tension.
Photo courtesy of ILSCO
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