Hi Tom
Salt water does conduct electricity better than fresh water but both are
highly conductive. Every bathroom apliance you own is labeled to avoid
water, and if you drop it in your fresh water bathtub it will electrocute
and kill you with the same 120v (US) thats on your boat, and far less
current.
Go to your bathroom, put an extension cord in the wall outlet and drop the
female end in your toilet. You will not damage anything as the breaker will
trip immediately. Watch the fireworks for the instant between contact and
the breaker tripping. Thats even less salty than any lake or stream and
you'll be convinced of just how highly conductive fresh water is right then
and there. The porcelan is highly NON-conductive so that leaves water as the
only conductor to ground.
You can do the same thing at the dock and I have an old extension cord on
my service truck with a bad female end on it that I demonstrate with
occasionally at the docks. Plug it in, drop it over and then tell me fresh
water is not conductive. You will never find saltwater in a home yet
hundreds are electrocuted every year with fresh water and electricity.
The easiect way to explain that fresh is less conductive than salt is to
use a quote I read once.
If salt water electrocutes you with 120v (US) then fresh will feel like 95v
but will still kill you. Double the numbers for 220/240 as it only takes 20v
+ of AC current to stop/seize heart/lung activity if electricity passes
through your chest. (From hand/arm to other hand or legs)
Just for the record your DC system in incapable of killing you. It takes
hundreds of volts of DC to do the same job, and boats have 24 at the most
but usually 12.
A note on alarmists, most of their worries are quite extreme and darn few
have any electrical knowledge at all but are selling their "for your safety"
products. To be electrocuted in a boat requires you to come into contact
with a bare wire, a shorted appliance or put a metal object into the outlet
and grabbing it. Ok well now your charged but with no ground you'll never
know it. Ever wonder why birds dont die on a power line? They are NOT
grounded and have no path to ground and neither do you on the boat unless
standing on something wet or in the water, or against something electrically
bonded to your engine/shaft/prop.. What little condictivity is around you or
touching you will let you feel some AC at times but normally won't kill you.
In the end as long as your electrical is squared away onboard your all set.
Look where your power leaves the deck plug and goes to your service panel
and them make SURE the white neutral wires and bare copper ground wires are
NOT connected/bonded together. If the boat only needed two wires ( one for
power, one for return path) there would not be three. Think about it, power
enters the appliance on one wire, leaves on the second wire and is case
grounded on the third. If the second and third are wired together then the
power leaving the appliance on the second wire (White return) can go to
your power panel, make a U-turn and travel the third wire (Green ground)
right back to the metal case of the microwave or stove. You touch the stove
and your sink at the same time YOU just became the shortest path to ground,
not only for your boat but the whole dock!
In many homes yes the neutral and ground are bonded, and the ground is
grounded by a ground peg outside, your water pipes or both and if they are
highly resistive it can travel outside and back into the power grid where
the neutral is grounded to earth on many power poles via a bare copper wire
traveling down the pole. Either way your covered and not sitting in water so
we can get away with this. The current code now does not allow this in
homes, now three wires need three independant connections. The bad part is
for years the same theory went into boat wiring. People the law requires
three seperate wires go down the dock for 120v, three seperate wires enter
the boat and it's for a good reason. One sends you power, the second carries
it back away, and the third is strictly for grounding and carrying away
voltage if and when there is a problem with an appliance to keep from
electrocuting you. If your bonding #2 and #3 in your boat then you have
defeated this basic concept and your back to the old two wire system
outlawed years ago. And then if you have a problem with your system, or if
anybody else on your dock has a problem with theirs you ALL have a problem
and finding it will be a real nightmare.
The best bet is to use ground fault breakers aboard and they ONLY work
correctly with the correct three wire setup, if your neutral and ground are
bonded they are NO better than a cheap old regular circuit breaker. They
"sense" the difference between the ground and return paths looking for a
difference or dicrepency, if they see one then they immediately trip.
HOWEVER... if ground and return are the same wire or bonded their advatage
is lost completely and without question.
Hope this helps
Claude
Arenal V1460
Salt water does conduct electricity better than fresh water but both are
highly conductive. Every bathroom apliance you own is labeled to avoid
water, and if you drop it in your fresh water bathtub it will electrocute
and kill you with the same 120v (US) thats on your boat, and far less
current.
Go to your bathroom, put an extension cord in the wall outlet and drop the
female end in your toilet. You will not damage anything as the breaker will
trip immediately. Watch the fireworks for the instant between contact and
the breaker tripping. Thats even less salty than any lake or stream and
you'll be convinced of just how highly conductive fresh water is right then
and there. The porcelan is highly NON-conductive so that leaves water as the
only conductor to ground.
You can do the same thing at the dock and I have an old extension cord on
my service truck with a bad female end on it that I demonstrate with
occasionally at the docks. Plug it in, drop it over and then tell me fresh
water is not conductive. You will never find saltwater in a home yet
hundreds are electrocuted every year with fresh water and electricity.
The easiect way to explain that fresh is less conductive than salt is to
use a quote I read once.
If salt water electrocutes you with 120v (US) then fresh will feel like 95v
but will still kill you. Double the numbers for 220/240 as it only takes 20v
+ of AC current to stop/seize heart/lung activity if electricity passes
through your chest. (From hand/arm to other hand or legs)
Just for the record your DC system in incapable of killing you. It takes
hundreds of volts of DC to do the same job, and boats have 24 at the most
but usually 12.
A note on alarmists, most of their worries are quite extreme and darn few
have any electrical knowledge at all but are selling their "for your safety"
products. To be electrocuted in a boat requires you to come into contact
with a bare wire, a shorted appliance or put a metal object into the outlet
and grabbing it. Ok well now your charged but with no ground you'll never
know it. Ever wonder why birds dont die on a power line? They are NOT
grounded and have no path to ground and neither do you on the boat unless
standing on something wet or in the water, or against something electrically
bonded to your engine/shaft/prop.. What little condictivity is around you or
touching you will let you feel some AC at times but normally won't kill you.
In the end as long as your electrical is squared away onboard your all set.
Look where your power leaves the deck plug and goes to your service panel
and them make SURE the white neutral wires and bare copper ground wires are
NOT connected/bonded together. If the boat only needed two wires ( one for
power, one for return path) there would not be three. Think about it, power
enters the appliance on one wire, leaves on the second wire and is case
grounded on the third. If the second and third are wired together then the
power leaving the appliance on the second wire (White return) can go to
your power panel, make a U-turn and travel the third wire (Green ground)
right back to the metal case of the microwave or stove. You touch the stove
and your sink at the same time YOU just became the shortest path to ground,
not only for your boat but the whole dock!
In many homes yes the neutral and ground are bonded, and the ground is
grounded by a ground peg outside, your water pipes or both and if they are
highly resistive it can travel outside and back into the power grid where
the neutral is grounded to earth on many power poles via a bare copper wire
traveling down the pole. Either way your covered and not sitting in water so
we can get away with this. The current code now does not allow this in
homes, now three wires need three independant connections. The bad part is
for years the same theory went into boat wiring. People the law requires
three seperate wires go down the dock for 120v, three seperate wires enter
the boat and it's for a good reason. One sends you power, the second carries
it back away, and the third is strictly for grounding and carrying away
voltage if and when there is a problem with an appliance to keep from
electrocuting you. If your bonding #2 and #3 in your boat then you have
defeated this basic concept and your back to the old two wire system
outlawed years ago. And then if you have a problem with your system, or if
anybody else on your dock has a problem with theirs you ALL have a problem
and finding it will be a real nightmare.
The best bet is to use ground fault breakers aboard and they ONLY work
correctly with the correct three wire setup, if your neutral and ground are
bonded they are NO better than a cheap old regular circuit breaker. They
"sense" the difference between the ground and return paths looking for a
difference or dicrepency, if they see one then they immediately trip.
HOWEVER... if ground and return are the same wire or bonded their advatage
is lost completely and without question.
Hope this helps
Claude
Arenal V1460