Preventing electrical failures…

How many of you have these terminal block connectors on board ?..


How many times have I seen so called professional marine electricians using this type of terminal block….Pitiful isn’t it !

There are so many type of electrical connector – all claiming to be for marine use ….

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imageThe ML-XT Sealed Connection System by Molex claims to be the best sealed system in the market today, preventing electrical failures in critical wiring applications. Premium grade liquid silicone rubber (LSR) material ensures the ML-XT connector system meets J2030 requirements for advanced sealing. The thermoplastic plug housing forms a covalent bond with the LSR seal, resulting in an extremely strong interlock which prevents fluid ingress and seal loss or misalignment, even through repeated mating and unmating. ML-XT connectors offer a better seal design and a better rating (IP69K), and are drop-in replacements for other industry standard connectors currently available.

Heat shrink v Don’t Heat shrink…

There are so many pieces of advice on how to seal wires on a boat …

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Will you be sealing moisture in?.. will the end allow water ingress and corrosion? Have you twisted the wire tempting strands to fail?… have you taken into account the surface conductivity property?

Probably the best method to join two wires is the solder splice type of connector with both solder and heat shrink techniques applied at once plus adhesive to stop water/humidity ingress…


If you are using non-tinned bare copper wire don’t twist the stranded wires together…. try to push each bunch of strands into each other so that as many surfaces are in contact as possible from each cable. This is because of the strange property of electrons to try and travel mostly at the outer surface of any given cable….

Tinned v Not Tinned copper wire ….

Then there is the debate on whether to use tinned or not tinned…

On the lab bench and under ideal circumstances, bare copper is going to outperform the `tinned’ variety. It isn’t quite that easy. If it was, we would be done, end of discussion. However, you can’t have an “age old argument” if the situation was straightforward can you? I have experienced different results than the lab testing would suggest. My own testing has proven both types of copper can be right if you add in the missing variable…time. Fresh, new, bare copper conductor works great. Unfortunately, I have found that it will oxidize much more quickly than the tinned variety which leads to a degradation in electrical performance.…

To the naked eye, a copper conductor may appear to be smooth and uniform, however microscopic pits and cracks still exist and moisture can easily penetrate these imperfections. The hydrogen atoms present in the water vapour will combine with other elements to form acids which eventually cause even more metal to be exposed by enlarging the imperfections in the base metal. It gets even worse when sodium is present as in the case of salt water. Sodium accelerates the chemical reaction that forms the destructive oxide compound. As more of these atoms combine they weaken the integrity of the original metal making it brittle and crumbly, a process commonly known as in practice use tinned – if you can afford it !


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