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THE IMPORTANCE OF WATERPROOF CONNECTORS IN MILITARY, MARINE,
TRANSPORT AND SOLAR APPLICATIONS by David Bushnell, Managing Director, Inelco Hunter
W
aterproof circular connectors are designed to protect power and signal connections from moisture, dust and
extreme weather conditions.
They feature sealed housings and robust locking mechanisms that keep the elements out. In outdoor projects, these connectors act as the lifeline of electrical systems by preventing corrosion and water ingress.
What makes a connector
‘waterproof’? A connector is ‘waterproof’ when it can prevent water, and dust, from entering its contact enclosure to a specified degree. To achieve this, waterproof connectors incorporate features like rubber O-rings, silicone seals, gaskets and sometimes epoxy potting around wires. Many also have sealing caps for when they’re not plugged in, maintaining protection even in an unmated state. It is quantified by Ingress Protection (IP) ratings, as defined by IEC 60529. Crucially, rated waterproof industrial connectors meet industry standards and tests for sealing. These include IEC standards for IP codes, and often MIL-SPEC or UL standards for ruggedness. It is prudent to note that some Amphenol connector series only achieve their full IP rating when mated, which is important when specifying components for field installations.
IP Ratings explained
Understanding IP ratings is key to choosing the right outdoor connector. The IP code has two digits: the first for solid particle protection and the second for liquid protection. For example, IP67 means dust-tight (6) and water-resistant against temporary immersion (7). Here is a quick summary of standard connector-relevant IP ratings:
IP65 Dust-proof; protected against low-pressure water jets from any direction. For outdoor light fixtures and weatherproof outlets designed to withstand rain or hose splashes. IP66 Dust-proof; protected against powerful water jets/heavy seas. For industrial equipment exposed to heavy spray or factory washdowns. IP67 Dust-tight; safe from immersion in water up to ~1m for 30 minutes. For outdoor connectors and sensors that might be briefly submerged or in flood-prone areas. IP68 Dust-tight; protected for continuous immersion beyond 1m. For underwater equipment, military applications, marine cables, or permanent outdoor installations where connectors may sit in water or soil long-term. IP69K Dust-tight; withstands high-pressure, high-temperature water jets (steam cleaning). To clarify, IP69K testing replicates hot, high-pressure cleaning procedures such as those used on heavy vehicles and industrial machinery.
Common materials used for
waterproof connectors Rugged materials are common for circular connectors. In fact, manufacturers like Amphenol LTW carefully choose housing and contact materials that can endure outdoor conditions. These include:
Thermoplastic housings. Many circular waterproof connectors use high-grade plastics like polycarbonate, nylon, or polybutylene terephthalate (PBT). These materials are lightweight, non-corroding and impact-resistant and can resist UV radiation so they don’t become brittle or cracked from sun exposure. Metal shells. Metal-bodied connectors are used when extra mechanical strength or EMI shielding is needed. Aluminium alloy shells with anodising
28 ELECTRICAL ENGINEERING • FEBRUARY 2026
or nickel plating offer a strong, threaded coupling and good corrosion resistance. Stainless steel shells are widely prevalent in connectors for marine and coastal environments. Hybrid designs. Some connectors or connector series combine metal and plastic, e.g., a nickel-plated brass shell with a plastic insert/backshell. This approach can balance durability and weight/cost. Amphenol’s Aquarius and Ecomate families include designs with UV-resistant thermoplastics and corrosion- resistant metal options for harsher marine and outdoor conditions.
The benefits of using
waterproof circular connectors Long-Term Durability Waterproof circular connectors are engineered for long-term durability in ways that standard connectors are not. Their sealed designs prevent corrosion of contacts and metal parts by keeping moisture out. Inelco Hunter strongly recommends Amphenol connectors because many of their waterproof connectors undergo salt-spray testing to verify corrosion resistance for marine or coastal use. This means that the connectors can withstand exposure to sea air or acid rain without rusting. Amphenol waterproof product lines are tested for 48+ hours, with some meeting or exceeding 500 hours of salt-spray performance, depending on the series.
Reliable Electrical and Signal
Performance Waterproof circular connectors do more than simply survive; they maintain strong electrical performance in harsh conditions. The sealing mechanisms prevent water or dust from intruding
electricalengineeringmagazine.co.uk
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