OK. Suppose you're thinking about wiring on your boat. You have three
"house lights" along the port side -- one over the nav desk, one over
the settee, and one in the V-berth. A reasonable thing to do
is run a pair of wires (+12 and GND) and take "taps" off them
at each point, for each lamp. Something like this

+12-----|--------|--------|
| | |
GND-------|--------|--------|
| | | | | |
X X X

where each "X" is a lamp. (View with constant width font!)

That's what's done in lots of boats, and lots of houses too. It
works OK. You have to size the "bus" wires to handle the aggregate
current of the three lamps, in case they're all on at once. You have
to worry a but about how you're going to attach the "taps" to the
bus wires. And you have to live with the fact that if the fuse/breaker
blose, you lose all three lamps at once.

Alternatively, you could run three sets of 18/2 wire (assuming low
wattage bulbs, short runs, etc.), but that seems a little silly.

Now...suppose you have a navigation light as well.

It's powered by a different circuit, with its own breaker. I'll call
this "12A".

Choice 1: run a 16/2 pair from 12A/GND-strip out to the nav light.

Choice 2: run a 16/1 wire from 12A to the nav light. Attach the other
side of the nav light as another "tap" on the ground bus shown above,
carefully resizing it to handle the larger load if necessary.

Assuming that you're doing all this in the *planning* stages rather
than after the fact, choice 2 doesn't seem so bad. Ignoring the
resistive effects of the wire (which are relatively small in this
application), it's electrically equivalent: the GND half of the 16/2
pair is attached to the ground -strip at the directribution point,
as is the GND bus above, so they're at the same potential, to a first
approximation.

As I'm thinking about wires and cabling, etc., it makes we wonder: "Do
I want to have dozens of circuits coming back from some cable, with
one wire going to the breaker panel, and the other wire from each
going to one of dozens of screws on a ground-strip? Or you I rather
just have one "master ground" that serves as the ground for ALL
the circuits that come out of that cable?"

Any thoughts here?

-John Hughes

--
ascii to ascii dos to dos


Greetz Bassie
"John F. Hughes" schreef in bericht
...
OK. Suppose you're thinking about wiring on your boat. You have three
"house lights" along the port side -- one over the nav desk, one over
the settee, and one in the V-berth. A reasonable thing to do
is run a pair of wires (+12 and GND) and take "taps" off them
at each point, for each lamp. Something like this

+12-----|--------|--------|
| | |
GND-------|--------|--------|
| | | | | |
X X X

where each "X" is a lamp. (View with constant width font!)

That's what's done in lots of boats, and lots of houses too. It
works OK. You have to size the "bus" wires to handle the aggregate
current of the three lamps, in case they're all on at once. You have
to worry a but about how you're going to attach the "taps" to the
bus wires. And you have to live with the fact that if the fuse/breaker
blose, you lose all three lamps at once.

Alternatively, you could run three sets of 18/2 wire (assuming low
wattage bulbs, short runs, etc.), but that seems a little silly.

Now...suppose you have a navigation light as well.

It's powered by a different circuit, with its own breaker. I'll call
this "12A".

Choice 1: run a 16/2 pair from 12A/GND-strip out to the nav light.

Choice 2: run a 16/1 wire from 12A to the nav light. Attach the other
side of the nav light as another "tap" on the ground bus shown above,
carefully resizing it to handle the larger load if necessary.

Assuming that you're doing all this in the *planning* stages rather
than after the fact, choice 2 doesn't seem so bad. Ignoring the
resistive effects of the wire (which are relatively small in this
application), it's electrically equivalent: the GND half of the 16/2
pair is attached to the ground -strip at the directribution point,
as is the GND bus above, so they're at the same potential, to a first
approximation.

As I'm thinking about wires and cabling, etc., it makes we wonder: "Do
I want to have dozens of circuits coming back from some cable, with
one wire going to the breaker panel, and the other wire from each
going to one of dozens of screws on a ground-strip? Or you I rather
just have one "master ground" that serves as the ground for ALL
the circuits that come out of that cable?"

Any thoughts here?

-John Hughes

I made groups of powerconsumers, ie navigation lights, cabin lights,
instruments etc etc
for each group i used one fuse.
From the switchpanel/fuseboard i run one wire for each group to a
terminalblock located central in my ship.
The negative wires run from a (diy) negative strip also to the
terminalblock.
I can distribute the powerfrom the terminalblock like a spiderweb trough
the ship.
The positive and negative "main" wires are bigger then the need to be, i did
that on purpose.
Every consumer has his own wires, and when i trun on a second light or
something else the power on each consumer stay's 12V.
For the vhf i made a special group, there is a switch for selecting a
battery. so when evreything goes wrong and the battery off the boardnet is
dead for some reason, i can switch it over to the starter battery.

When i was making the group for the cabinlights, i divided the cabin lights
in to two different groups, one group is the bow section, the other one is
the stern section.
I placed one light of a group in the other group, so if the fuse blow's of
the bow section, there is on light that can be used and if the fuse blow's
of the sternsection there is one light in the stern section that can be
used.

The diy negativestrip is a piece of chrome'd copper with lot's of koper
screw's in it.
I have made electrical drawings of my system so i can send you a copy if u
want.

The fuse/switchboard is also diy, i can send a picture of that as well



--
ascii to ascii dos to dos


Greetz Bassie

This is basically a "Common Ground" question. There are two approaches,
and they are both workable.. depending on which is more reasonable on
your particular boat, and it's configuration and wiring access.

First, if you're building or rebuilding a boat, I strongly recommend that
you install a run of plastic (Typically PVC) electrical conduit along one
side of the boat (typically the right if a right-wheel powerboat),
located just below deck along the sheer. Run this from stem to stern, and
size it bigger than you think you need! I last used 1 inch ID and it wish
I went to 1 1/2" ID. At each useful location, such as electrical panel,
engine, bulkhead etc, either install a junction/pull box or simply cut
away about 90 degrees of the conduit for an inch or so. It's easy to
install wiring by pulling it thru the conduit, and a stiff metal 'snake'
can be pushed from one location to another to add wiring later. You will
add things you never thought of at the beginning. This is just a
mechanical way of taming the "Rats Nest" seen in some boats. Now to the
grounding issue.

I am in favor of running a LARGE (Say #00 cable) ground cable from stem
to stern, that is well bonded to the rudder shaft, the propshaft and
stuffing box, the engine block (also battery negative common point),
hull seawater grounding plate(s) if used, the mast base (if sail), the
"metal above the head" such as windshield frame, top-mounted antennae
bases, radar, weather instruments, stays, safety rails, anchor chains,
etc. I have run rubber covered welding cable, and also plastic-covered
power cable for this ground, and the routing of it is a tradeoff. It
would be nice, electrically, and lightning-related, to run it right down
the center bilge, and I've done that, but had some corrosion problems
after 10 years or so. Last boat I ran it along the chine, thru holes
drilled in the frame, with a major side tap to the power panel area. IF
that had been a sail, I'd have run a large tap down (Or over) to the mast
base.

But, back to Grounding. The two main choices a Run all grounds to the
nearest tap on the one large grounded conductor (Common Ground), or (Star
Connection) run separate power and ground conductors from every load back
to the power panel area, and a single ground point there. I have chosen
a compromise: Larger loads go directly to the large ground conductor, and
only send the power feed from the power panel. Smaller miscellaneous
lighting, horn, etc have two (typically twisted) wires run from the power
panel. Simply easier to wire.

What are the tradeoffs? Here's what I see (comments and experiences
desired):
(1) Voltage drop: Minimize voltage drop in ground circuits by fairly
direct connection to large low-resistance ground conductor.
(2) Size / ease of wiring: two wires easy for small stuff, single feed /
less wire for large stuff.
(3) Electrolytic corrosion: There are two concerns: (A) circuits with +12
or +24 on them HAVE to be well insulated and dry or corrosion will occur.
(B)"Ground" connections that may well have dampness and salt near or on
them need to have the lowest practical resistance between them, and the
least constant current through them, to minimize voltage drop which
causes electrolytic corrosion.

The high-current paths (battery-alternator-starter) should obviously be
separate from the rest of the boat systems, and well insulated and
protected from dampness and corrosion. They get connected the the rest
of the boat in two places: Battery negative/engine block to the boat
grounding system discussed above, and battery positive (typically from
battery switch(es)) to power panel.

I'm pretty amazed at the number of boats that have major items like
masts, stays and rudders ungrounded...

Comments appreciated; there's more than one way to skin a ground
conductor.
--
Regards, Terry King ...In The Woods In Vermont

The one who Dies With The Most Parts LOSES!! What do you need?

A couple of common rules:
1: NEVER connect ANYTHING that carries ground current to your boats
bonding system.

You do not want any current differences on the bonding system. If you
connect a current carrying item to the bonding system you WILL have
small voltage drops in the bonding line and that will provide small
voltage differences in underwater items that are bonded. That equals
electrolysis corrosion.

You want one connection of the bonding system to the dc electrical
system and that should be at the engine block or at the battery.

2: Always run separate ground and hot leads for each piece of
equipment that you are powering.

It avoids ground current loops that cause interference with other
electrical items. It also prevents overload of ground leads.

The exception to this would be a distribution panel or terminal blocks
where you have a heavy pair of leads (ground and hot) feeding that
point and then supplying smaller loads from those terminals.
But those terminal blocks should all be fed from one point only. The
engine block or the battery. Which ever you chose as the common ground
point on the boat. Do not feed some grounds from the battery and some
from the engine block.

Regards
Gary


On Fri, 19 Mar 2004 11:11:55 -0500, Terry King
wrote:

This is basically a "Common Ground" question. There are two approaches,
and they are both workable.. depending on which is more reasonable on
your particular boat, and it's configuration and wiring access.

First, if you're building or rebuilding a boat, I strongly recommend that
you install a run of plastic (Typically PVC) electrical conduit along one
side of the boat (typically the right if a right-wheel powerboat),
located just below deck along the sheer. Run this from stem to stern, and
size it bigger than you think you need! I last used 1 inch ID and it wish
I went to 1 1/2" ID. At each useful location, such as electrical panel,
engine, bulkhead etc, either install a junction/pull box or simply cut
away about 90 degrees of the conduit for an inch or so. It's easy to
install wiring by pulling it thru the conduit, and a stiff metal 'snake'
can be pushed from one location to another to add wiring later. You will
add things you never thought of at the beginning. This is just a
mechanical way of taming the "Rats Nest" seen in some boats. Now to the
grounding issue.

I am in favor of running a LARGE (Say #00 cable) ground cable from stem
to stern, that is well bonded to the rudder shaft, the propshaft and
stuffing box, the engine block (also battery negative common point),
hull seawater grounding plate(s) if used, the mast base (if sail), the
"metal above the head" such as windshield frame, top-mounted antennae
bases, radar, weather instruments, stays, safety rails, anchor chains,
etc. I have run rubber covered welding cable, and also plastic-covered
power cable for this ground, and the routing of it is a tradeoff. It
would be nice, electrically, and lightning-related, to run it right down
the center bilge, and I've done that, but had some corrosion problems
after 10 years or so. Last boat I ran it along the chine, thru holes
drilled in the frame, with a major side tap to the power panel area. IF
that had been a sail, I'd have run a large tap down (Or over) to the mast
base.

But, back to Grounding. The two main choices a Run all grounds to the
nearest tap on the one large grounded conductor (Common Ground), or (Star
Connection) run separate power and ground conductors from every load back
to the power panel area, and a single ground point there. I have chosen
a compromise: Larger loads go directly to the large ground conductor, and
only send the power feed from the power panel. Smaller miscellaneous
lighting, horn, etc have two (typically twisted) wires run from the power
panel. Simply easier to wire.

What are the tradeoffs? Here's what I see (comments and experiences
desired):
(1) Voltage drop: Minimize voltage drop in ground circuits by fairly
direct connection to large low-resistance ground conductor.
(2) Size / ease of wiring: two wires easy for small stuff, single feed /
less wire for large stuff.
(3) Electrolytic corrosion: There are two concerns: (A) circuits with +12
or +24 on them HAVE to be well insulated and dry or corrosion will occur.
(B)"Ground" connections that may well have dampness and salt near or on
them need to have the lowest practical resistance between them, and the
least constant current through them, to minimize voltage drop which
causes electrolytic corrosion.

The high-current paths (battery-alternator-starter) should obviously be
separate from the rest of the boat systems, and well insulated and
protected from dampness and corrosion. They get connected the the rest
of the boat in two places: Battery negative/engine block to the boat
grounding system discussed above, and battery positive (typically from
battery switch(es)) to power panel.

I'm pretty amazed at the number of boats that have major items like
masts, stays and rudders ungrounded...

Comments appreciated; there's more than one way to skin a ground
conductor.