[EMAIL PROTECTED] wrote: > > I've just gotten into this buss discussion (late) and may have missed > something, but I would have little concern about fire from shorts > since your hull is not fiberglass. Watching a fiberglass boat burn > gives me nightmares and cause for extreme wiring caution. The one > thing that concerns me, and I may have misunderstood something, but > there seems to be no mechanical connection in the "stick-on solder > taps". You obviously have had no problem, but I would feel better with > wrapped wire, then soldered, or some type of mechanical clamp on and > soldered or something other than just stuck on soldered wire. > > Ed Schwerin REPLY I did build such a system back in 1996. I used 1" X 1/4" solid copper bus bars. For sharp turns I made flexible joints using multiple flexible conductors with bolted ring connectors. Combined ampacity of these flexible cables exceeded the ampacity of the solid bus bar. Tap off points were also made to breaker panels located at suitable intervals. The tap of points were done with #4 ga wire and a 100A panel breaker installed. This in turn fed 6 or 8 breaker positions and the breakers were connected with a 100A bus which is pretty standard for most commercial panels like Blue Sea systems. This system was tested to deliver 400 Amps at no more than 1% voltage drop at the remote end. The bus bars ran down both sides of the hull but as an added measure I closed the loop at both ends, effectively forming a ring circuit. The in-feed point right next to the battery disconnect switch was fused with a Class T 400 Amp fuse to protect against short circuit faults. Class T fuses are about the only HRC devices that will not burst into flame if subjected to a dead short. When you have a 1000 amp hour battery bank fully charged, a short circuit could produce fault currents in excess of 10,000 amps for the duration before the fuse ruptured. circuit breaker have a hard dime matching that level of fault current protection..
When I worked for a power utility company at one time, we always used HRC fuses for any distribution load circuit requiring more than 100 Amps. The one exception being our main 2 megawatt transformer station. It had 16 distribution feeders for 600 Amps @ 27,600 volts, each protected by circuit breakers. Mind you each one of those 600 Amp breakers for 27,600 volts probably cost more than what a whole boat cost. <grin> Each breaker also weighed around 1000 pounds. Because I had used bare copper bus bars, we sprayed on a rubber compound after all connections were made, tested and verified as good. This protected against any brush contact. The entire bus duct-way was also covered by an exterior cover but the brush contact protection ensured that a minimum of conductor was exposed even during service work. The rubber compound had better characteristics than ordinary PVC insulation. For anyone contemplating doing this in a metal hulled boat, I would recommend doing a megger test from conductor to conductor and from conductor to hull. None of the wiring was run through any engine compartments. This was all done above deck level and all machinery located below that deck level. This system was made entirely to power lighting and entertainment systems. The one drawback was if we had to add an additional tap of point at some future time. Then the copper bus bar would have to be wire brushed clean and polished to ensure good contact at the new attachment point. connections were made by drilling and tapping for #12 screws. The buss bars were supported in custom made electrical grade PVC blocks that allowed some slight movement back and forth. the blocks were screwed to the ribs. Solid copper bus bars will elongate slightly when heated due to current flow. So the PVC blocks and flexible joints accomodated the movement that might otherwise have causes stress cracking. Bus bar lenght was 30 feet for longest run on any one individual piece. For the AC power system a similar approach was made. However stranded commercial wires was used throughout to ensure it met electrical code requirements. Standard UL/CSA certified power panels were also used throughout.. These sub panels had sufficient bolt-on connections that I could feed in power and then run additional wire to the next sub panel. In effect the existing panel bus bars provided the necessary tap -of points to a set of breakers. For consistency I used the same 8 circuit box for all ocations even though I only used 3 or 4 positions. The extra capacity allowed for future expansion. System was fed by a couple of inverter totalling 6kW. The ring feed structure effectively lowered the current being conducted in any section although the over current protection was selected as if the circuit was linear and a single run. Typically this meant the actual load current was around 2/3 to half as much as normally experienced since power was derived from both halves of the ring. > regards, Arild _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [EMAIL PROTECTED] To unsubscribe send an email to [EMAIL PROTECTED] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
