Provide Proper Relief From Wiring Strain

by Kevin V. O’Neill

Whenever you’re connecting wiring to any stationary equipment, it’s important from both an equipment reliability standpoint and a safety standpoint to use the proper strain relief.

If you’re running romex or thermostat cable into a cabinet, install a romex connector in the cabinet opening. This protects the cable from being worn through by the sheet metal edges of the cabinet. If the cable is encased in armored cable, use the appropriate connector.

When using flexible liquid-tight conduit, use the correct connector. I often see PVC conduit connectors glued onto the flexible liquid-tight conduit. That flex isn’t made of PVC, and the solvent cement won’t hold it very long. Over time, the flex pulls out of the connector, exposing the wires to
possible damage.

If you’re installing romex in any type of conduit or flex, first strip the outer jacket off the romex, then fish the individual wires through the conduit. If you fail to remove the romex outer jacket, both the temperature rating and the current carrying rating of the wire are reduced.

When using flexible plastic conduit outside, don’t use any section longer than 6 ft. between the disconnect box and the unit. If you need to make longer runs, use conduit with a spiral metal core inside the plastic flex.

Kevin O’Neill, CM, is the owner of O’Neill-Bagwell Cooling & Heating, Myrtle Beach, SC. He has 27 years experience in the HVAC service business and is a 20-year member of RSES. Kevin can be reached at 843/385-2220.

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