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By John Rezabek, Contributing Editor
If you're unprepared for the Apocalypse, you and I have that in common. But what if our workplaces are battered by plagues of locusts, floods, hurricanes and/or earthquakes? What's the likelihood your terminations will stay under the screws? I wouldn't sneeze at the decades-old quality installations our craftsmen have done for us, but if conditions deviate significantly from the norm, could anyone begin to guess where weak links might appear? There are a few strategies that can help keep circuits hanging on when the locusts hit the fan.
Where's the worst place on the planet for terminations? I think offshore platforms in the North Sea probably would make the Top 10. Companies that specialize in providing termination hardware for this environment, like Hawke International, manufacture connectors and cable glands that are rated IP67 (dust-tight and submersible in 1 m of water) and higher, deluge-resistant and impervious to salt-spray corrosion. Amphenol makes a line of connectors called Amphe-EX that carry hazardous-area ratings and are rated IP68, which means they're tested for sustained submersion in over a meter of water. The line includes accommodations for standard RJ45 Cat. 5/Cat. 6 Ethernet terminations and USB connectors. But even if you're not wiring an offshore platform or an M1A1 tank, the strategies employed can find some applicability in more pedestrian installations.
Their on-shore cousins like the Turck mini-fast connectors have found wider application, and might be more affordable if you don't have oil production or defense-industry funding. They're also rated to IP67 and have been service-tested in U.S. Gulf Coast installations that became submerged in the wake of hurricanes.
Pre-manufactured cables with high-integrity quick-connect terminations might have additional features aside from being convenient and submersible. For example, I've heard of a number of developing-world installations that have been plagued by inadequate electrical craftsmanship (i.e., loose, missing or wrong terminations). If you can employ pre-manufactured cables, you have a chance to move the majority of the terminations from the field to a more controllable and hospitable shop or factory. The manufacturer's factory or module constructor's shop affords a potentially easier place where you can inspect them and create a higher level of accountability for the workmanship. The focus shifts from training and enforcing a level of craftsmanship in a remote area, where indoor wiring could be scarce, to specifying and inspecting effectively with OEMs and packaged equipment or module suppliers.
One specification you might be well advised to call out and enforce is the torque required for finished screw terminals. Even if you're employing quick connects, at some point these will most likely transition to screw terminations, whether inside devices and instruments or at the control system's I/O and marshalling panels. On a project for which we employed mini-fast connectors, we found a significant number of in-device terminations that either were never tightened sufficiently, or vibrated loose in transit to the work site. Fellow contributing editor and network guru Ian Verhappen has done ad-hoc audits of terminal tightness and found 100% of the terminals were not tightened to the terminal manufacturer's recommended torque. You can purchase some precision torque screwdrivers from your favorite terminal suppliers—Phoenix Contact and Weidmüller sell similar models—but bear in mind that the precision of the calibration is affected by how it's used/abused and stored. Routine maintenance and calibration checks might need to become part of your shop's routine.
Since it's apparent there's a craft and finesse to using the tools and installing reliable terminations, many have found it worthwhile to spend some time training the crews doing the work, even if many are seasoned journeymen. It need not be condescending. You can bring in a little pizza, kolaches, or whatever the local custom might be. During the construction of the largest refinery on the planet, Bechtel engineers Dave Brown and David Lancaster trained their electricians in Jamnagar, India, on how they wanted junction boxes constructed. After thousands of networks were installed, they could count the errors on one hand.
“One specification you might be well advised to call out and enforce is the torque required for finished screw terminals.”- John Rezabek
Being the facility that stays online during the blizzard, recovers quickly following a calamity, or rapidly completes a loop check and startup can mean exceptional opportunistic profitability for your facility. Should conditions get dicey, having ensured solid terminations can help your enterprise be the one that prospers and endures.