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My old wooden fuse panel,..
I do this kind of stuff for a living, but for industrial control systems.
NFPA, UL, CE, ABYC, and local country regulations all apply and vary from one place to another. In most places, you can do what you want in your private boat and something like case law is going to apply more directly than regulations. It's different if you are building a boat to sell or otherwise producing a commercial product. I'm not directly familiar with all the marine wiring rules, but the one that appears to be most acceptable internationally appears to the be the American Boat and Yacht Council (ABYC) regulations. Section E-11 is on AC and DC electrical systems. In that section, it mentions that you must have energized electrical wiring either enclosed or otherwise protected so that people do not get injured. In a nutshell, it means to keep your system touch-safe. Terminals and other connections should either be inside a housing or enclosure or should use insulation or touch-safe type guarded terminals. I do not believe that the type of backplane or enclosure material is specified, and don't believe that there are any rules on that. Many ARE metal (conductive). I see nothing that disallows wood or fiberglass. 120 VAC is *not* inherently touch safe and should be guarded. 24 VDC or 12 VDC *is* inherently touch-safe and does not necessarily need to be guarded although accidental short circuits caused by conductive things (tools etc) touching these things should be prevented. I'm not sure that you really want to bring your whole boat up to snuff when it comes to standards because it'll likely impact many things and take some time and money. If it were me, I'd make sure the electrical system is designed properly and guarded properly. Read up on disconnects, branch circuit protection, wire gauges etcetera and make sure that you have the appropriate circuit protection in place ...noting that this is for fire protection only. For device protection, you can either limit the circuit protection to a smaller-than-required value appropriate for the device or provide supplemental protection for the device (additional circuit breakers or fuses). Use good practices such as not having more than two wires per screw terminal, strain relieved terminators (designed to crimp onto the conductor AND the insulation), etcetera. For wiring throughout the boat, make sure you don't have exposed metal unless it is touch-safe and you're OK with the exposure, e.g. low risk of shorting with tools or other things. Enclose your buss bar, breakers, terminal strips, switches etcetera in a way that protects people from shock. That may mean a door that closes over the wiring, simple guards, or whatever. Just be reasonable. Commercial marine installations use NEMA-4X / IP-66 as a minimum rule for exposed or semi-exposed enclosures, and if in open exposed areas often enclose the enclosure inside an outer 'rainshed' type enclosure that keeps ocean spray off the NEMA-4X enclosure ...overkill for your privately owned yacht. Just use good practices, protect against fire, and protect against shock. There are several books that help and provide the info that will allow you to meet these goals: Nigel Calder's book, "Boatowner's Mechanical and Electrical Manual" is a very good addition to your library. There are others such as the "12 Volt Bible" but they are more basic and have less information ...but still worth owning I think. Again ...I've never seen anything that disallows wood as an enclosure, backplane, or anything else. If you use a conductive material for these things, then you must isolate them. If your wood may get soaked with something conductive such as sea water, the same rule applies (of course you should prevent this from happening except for the outer enclosure ...and only if it properly protects the interior from spray.) Brian D "ray lunder" wrote in message ... Does this require a metal enclosure? I live in WA state if it makes any difference. The boat was British built originally but now has current WA state registry. I have slogged through the electrical code and I still can't find a part that's clearly states "thou shalt not have a wooden panel". Mine is just a plywood box with a tip-out but the buss bars are on proper insulative stuff with copper screws, fuses, switches, labels and correct wire gauges. It all stands off from the ply and cabinetry but not by much. On a similar sized sailboat, 23', the "panel" was a piece of insulative with 8 circuits comprised of fuses and switches hanging down in an L from the fiberglass hull. No proper enclosure at all, just a bare face. I could only find one boat sized metal panel and it was $100 for an empty box with a door and two knock-outs. I'm open to suggestion as always and thanks again. |
#2
posted to rec.boats.building
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My old wooden fuse panel,..
I think NFPA says 60 volts for touch-safe. For the great majority of circuits, there's nothing anywhere near that ...120 VAC and either 24 or 12 VDC seems to be the rule ...DC is usually touch-safe and AC usually is not. That's why I generally forget the exact definition of what voltage is touch-safe and not ... ;-) Brian D "derbyrm" wrote in message newsCIOf.7067$oL.3979@attbi_s71... Good advice! Just a few points to add. UL defines "touch safe" as less than 40 volts. Since this would be 28 volts RMS for AC, we get that usage. (28 volts is the charging voltage for a 24 volt battery bank.) A practical guide might be the considerations involved in wiring barns. Metal conduit is prohibited because it will corrode and lose its integrity. (high humidity -- cows sweat) A great variety of PVC conduit, both rigid and flexible is available as are the boxes and other fittings. Any wire that might be cut by something bumping into it must be protected either by conduit or by a barrier; e.g. a wooden 1 x 2. While the regulations are for 120 vac circuits, the general ideas are valid since you don't want to lose your autopilot or instrumentation systems just because you stowed a case of beans carelessly. For your shoreside circuits, you do want to provide good protection. No holes where a child's finger can reach a conductor. For spaces that might contain an explosive atmosphere one gets into a whole new realm of enclosures. Bilges might end up with propane or gasoline fumes? Keep the spark generating devices well away. The common use of metal enclosures may be partially dictated by RF noise considerations too. I've a bad fluorescent light fixture which now wipes out the FM radio and can't be fixed until my boat hull is strong enough to climb on. Roger http://home.insightbb.com/~derbyrm "Brian D" wrote in message . .. I do this kind of stuff for a living, but for industrial control systems. NFPA, UL, CE, ABYC, and local country regulations all apply and vary from one place to another. In most places, you can do what you want in your private boat and something like case law is going to apply more directly than regulations. It's different if you are building a boat to sell or otherwise producing a commercial product. I'm not directly familiar with all the marine wiring rules, but the one that appears to be most acceptable internationally appears to the be the American Boat and Yacht Council (ABYC) regulations. Section E-11 is on AC and DC electrical systems. In that section, it mentions that you must have energized electrical wiring either enclosed or otherwise protected so that people do not get injured. In a nutshell, it means to keep your system touch-safe. Terminals and other connections should either be inside a housing or enclosure or should use insulation or touch-safe type guarded terminals. I do not believe that the type of backplane or enclosure material is specified, and don't believe that there are any rules on that. Many ARE metal (conductive). I see nothing that disallows wood or fiberglass. 120 VAC is *not* inherently touch safe and should be guarded. 24 VDC or 12 VDC *is* inherently touch-safe and does not necessarily need to be guarded although accidental short circuits caused by conductive things (tools etc) touching these things should be prevented. I'm not sure that you really want to bring your whole boat up to snuff when it comes to standards because it'll likely impact many things and take some time and money. If it were me, I'd make sure the electrical system is designed properly and guarded properly. Read up on disconnects, branch circuit protection, wire gauges etcetera and make sure that you have the appropriate circuit protection in place ...noting that this is for fire protection only. For device protection, you can either limit the circuit protection to a smaller-than-required value appropriate for the device or provide supplemental protection for the device (additional circuit breakers or fuses). Use good practices such as not having more than two wires per screw terminal, strain relieved terminators (designed to crimp onto the conductor AND the insulation), etcetera. For wiring throughout the boat, make sure you don't have exposed metal unless it is touch-safe and you're OK with the exposure, e.g. low risk of shorting with tools or other things. Enclose your buss bar, breakers, terminal strips, switches etcetera in a way that protects people from shock. That may mean a door that closes over the wiring, simple guards, or whatever. Just be reasonable. Commercial marine installations use NEMA-4X / IP-66 as a minimum rule for exposed or semi-exposed enclosures, and if in open exposed areas often enclose the enclosure inside an outer 'rainshed' type enclosure that keeps ocean spray off the NEMA-4X enclosure ...overkill for your privately owned yacht. Just use good practices, protect against fire, and protect against shock. There are several books that help and provide the info that will allow you to meet these goals: Nigel Calder's book, "Boatowner's Mechanical and Electrical Manual" is a very good addition to your library. There are others such as the "12 Volt Bible" but they are more basic and have less information ...but still worth owning I think. Again ...I've never seen anything that disallows wood as an enclosure, backplane, or anything else. If you use a conductive material for these things, then you must isolate them. If your wood may get soaked with something conductive such as sea water, the same rule applies (of course you should prevent this from happening except for the outer enclosure ...and only if it properly protects the interior from spray.) Brian D "ray lunder" wrote in message ... Does this require a metal enclosure? I live in WA state if it makes any difference. The boat was British built originally but now has current WA state registry. I have slogged through the electrical code and I still can't find a part that's clearly states "thou shalt not have a wooden panel". Mine is just a plywood box with a tip-out but the buss bars are on proper insulative stuff with copper screws, fuses, switches, labels and correct wire gauges. It all stands off from the ply and cabinetry but not by much. On a similar sized sailboat, 23', the "panel" was a piece of insulative with 8 circuits comprised of fuses and switches hanging down in an L from the fiberglass hull. No proper enclosure at all, just a bare face. I could only find one boat sized metal panel and it was $100 for an empty box with a door and two knock-outs. I'm open to suggestion as always and thanks again. |
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