[PSUBS-MAILIST] Wire type for submersibles

[Alan James via Personal_Submersibles]

 This is a summary of what I have been researching on wires. Steve wanted to hear this, but I would appreciate any other words of wisdom on this subject.   As a generalization G.L. says protective coverings, sleeves, sheaths & fillers are to bemade of halogen free materials. This is because they are toxic & acidic when burning.PVC has halogens in it, & it is a common insulation on marine grade wire! Also PTFE(Teflon) insulation has halogens. Subconn connectors have PTFE wire insulation that runsin to the hull.In my view the halogen content won't matter if the wire is outside the hull. G.L. does say that materials & insulations for electrical equipment used in water are to be agreed with G.L. in each single case.G.L. also says insulation must be resistant to saltwater & oil vapors, not be hydroscopic & has to be flame retardant & self extinguishing.PTFE has a very high flash point so possibly gains approval for internal use from that perspective.   There is a standard for electrical cable for boats "UL1426", & when you search for marine electricalwire it will quote a standard like that.For sizing wire for submersibles ABS refers you to part 4, chapter 8 of the "steel vessel Rules" &table 6 in section 3.   It started to get complicated as G.L. have a section Annex E that deals with umbilicals etc.I came to the conclusion that I would use a PVC insulated marine grade wire that conformed to the UL1426 standard for external use. And use PTFE insulated wire inside the hull. My thinking on goingwith PVC over PTFE externally is that my glues would be more likely to stick to PVC than Teflon (PTFE) on my home baked through hulls.Cheers Alan


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