-----Original Message----- From: Robin Brueckner While I would not recommend solid copper wire for general use aboard a boat, in some applications it's preferred, like the main bonding conductor in a bilge because of corrosion resistance. (A strap is preferable, however, perhaps even soft copper tubing.) REPLY I was asked to verify the adequacy of copper plumber's strapping. the kind that has holes about one inch apart. The strap is widened around the holes giving the strp a peculiar appearance. Caliper measurements confirmed the cross ectional area of this strap is equivalent to the cross sectional area of #12 AWG wire. For simple bonding to protect fitings against galvanic corosion thi is adequate. BUT!!! ABYC require th ebonding system to be made from #8 AWG if the bonding system also serves as lightning protection. In which case the plumbers copper strapping is NOT ADEQUATE! A related issue is the fineness of wire stranding. Home Cheapo stranded wire, for example is composed of a limited number of relatively thick strands which is apparently less expensive to manufacture than real marine wire with finer strands. It's rather inflexible compared with finer strand marine cable, but works satisfactorily in many applications. I have about 5,500 feet of it aboard my Hatteras. REPLY Incidentally stranded cable is classed in three catagory; #1 #2 and #3. A few years ago ABYC amended their standard to only allow #3 stranding. #3 is th efinest stranding and #1 is really coarse with only seven strands making up the whole wire. This typically what you get with stove and dryer wiring. Solid conductor in that gage is almost impossible to bend around corners. Welding cable I have seen, apparently made for portable application and frequent flexing, has finer strands than marine cable which is moderately flexible by comparison. I suspect it may be more readily subject to salt water corrosion. REPLY Yes and for good reason. ABYC specifically prohibits such fine stranding because it acts like a wick and capilliary action will wick up a lot of salt water in the event a cut end is immersed or accidentally flooded even momentarily. For an example of fine mesh strapping; it is used in automotive applications such as bonding the hood to the rest of the car body and frame. Open ended rings on crimp lugs that leave the cut end exposed is a perfect example. Despite a good crimp, salt air can stil get into th efine stranding and rot the wires. If any voids exist this corrosion can creep up past th ecrimp point and damage the whole cable. Unless you use a hydraulic press box crimping die set, there will be voids. I have the hand opeated dimple die crimper tool and have cut a section of a "good" crimp to see. Examination under a microscope reveals voids. For this reason I prefer the closed end bell style and use of an anti-oxidant paste. This paste is available at all electrical supply houses. Electricians use it for aluminum power cables in industrial work. DO NOT USE SILICONE SEALANT. It contains acetic acid and will cause internal corrosion in the crimped end. Arild