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.