When searching for cord-locking mechanisms to prevent accidental or abrupt disconnects from IEC 60320 power inlets such as the IEC 60320 C13, beware of the type of metal locking mechanisms (one unfortunately approved by a well-known agency) that tightly clamp onto notched grounding blades, a tight metal-on-metal retention resulting in a dangerous loss of material on the grounding blade. This friction, similar to striking a flint to produce sparks, creates carbonized buildup around the terminal after repeated disconnects, which could lead to an electrical fire through repeated arcing. Carbonized buildup may also appear on alloy pins if those pins are molded a fraction too close together, the narrow space between them providing small enough air gaps for the current to jump from one pin to the next. This would also apply to metal screws on the plug face of rewirable cord sets.

But what about moisture?

Arcing & Moisture

Moisture decreases resistance between circuits which may create an unwanted electrical pathway from one circuit to another (path of least resistance). This may lead to short-circuiting, electrical shocks, and electrical fires.

Common moisture issues are far less conspicuous than seeing and avoiding a live wire sparking near a water source. Insidious, moisture creeps its way into an electrical cord’s conductors and creeps into microscopic crevices around blades, pins, and other terminals/contacts setting the stage for corrosion and its coconspirator, arcing. Moisture seeps into cables (and in very humid climates via extremely damp air) and damaged cord jackets, seeping and absorbing into cardboard cord fillers and other insulation material thus reducing its resistance and insulation potential. Interpower always recommends using moisture-resistant devices (ingress-protected components or desiccants) in wet or moist areas while regularly inspecting plugs, connectors, and cables for damage where moisture inconspicuously erodes electrical continuity, or worse, poses a threat to human life.

Gaps & Tracking

Over time, carbon buildup and imperfections such as debris, cavities, corrosion, and cracks allow arcs to “track.” Tracking is the flow of electricity along plastic surfaces where the air gaps are too narrow to extinguish or dampen the arc. Depending on your electrical design and other combustible factors, continual tracking may even cause large explosions if given the chance to track long enough to ignite combustibles such as a host of industrial dusts: carbonaceous, metallic, plasticized, chemical, and others. Widening air gaps is one solution to extinguish arcs and tracking. Conversely, however, designing the plug bridge to slightly add more distance between blades and pins on your molded cord set may take blades and pins out of specification by +/- thousands of an inch/mm beyond agency “X’s” tolerances listed in their standards. Also, electrical wire that is over-crimped can break and potentially cause arcing while flattening a B crimp so much as for it to fail an electrical continuity test through lost surface area. And, there may be gaps along a “bad” crimp that potentially could arc. In truth, the subject of electrical arcing possibilities could fill hundreds of white papers.

Arc Resistance

Arc resistance is measured in the time (seconds) it takes to make an insulating surface conductive under a high voltage/low current arc in controlled environments. Arc resistance in electrical cord sets and components is commonly hipot tested at a higher current than what the product is rated, e.g., a cord set rated at 220VAC may be hipot tested at or near 320VAC. Put another way, arc resistance is the degree of a plastic’s resistance to arcing and the formation of additional conductive paths along its surface—the longer it takes to arc, the less conductive and more resistant your plastic material is to arcing.

So, Looking for a connector lock that’s solid without ruining your grounding pin, or burning down the place? Check out Interpower’s dynamic duo—Tool-Free or Locking-Screw locks—at Interpower Connector Locks.