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Having disconnected and labeled all the 12 V wiring, the 110 AC is
now visable. It appears that all the AC ground wires (green) are run to a common buss. But , then, the AC Ground buss is connected with a 6 ga. wire to the DC negative buss. This doesn't seem right to me. Is it? |
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Marc, unless you're in mid-ocean at the moment, I think now is the time
to purchase a book on marine electrical wiring. Read through it and then post any questions that remain. Be glad to help. Good luck. Chuck Marc wrote: Having disconnected and labeled all the 12 V wiring, the 110 AC is now visable. It appears that all the AC ground wires (green) are run to a common buss. But , then, the AC Ground buss is connected with a 6 ga. wire to the DC negative buss. This doesn't seem right to me. Is it? |
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Marc wrote in news:ufm1p1h2l7qr8s8vs3vbso6j1so1l3apgr@
4ax.com: Having disconnected and labeled all the 12 V wiring, the 110 AC is now visable. It appears that all the AC ground wires (green) are run to a common buss. But , then, the AC Ground buss is connected with a 6 ga. wire to the DC negative buss. This doesn't seem right to me. Is it? They do this to insure your engine, underwater propulsion gear and everything hooked to the DC ground system is connected to every other stupid boat and the marina's big earth ground system, making one HUGE battery out of those zincs you can't figure out why they disappear so fast. There's absolutely NO reason why the independent DC system should be connected to the AC ground bus I know of. Ours isn't. I'll be damned if I'd pay with MY zincs to protect your prop because my zincs are hooked through the AC wiring ground to your zincs..... Oh, hooked up like that, too, your zincs are protecting the whole electrical system of HIS marina any place it touches the water or makes contact with the earth. Aren't you being, inadvertently, nice....(c; |
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So are you complaining that the AC ground and DC negative are both connected
to the boats ground or where they're connected? "Larry" wrote in message ... Marc wrote in news:ufm1p1h2l7qr8s8vs3vbso6j1so1l3apgr@ 4ax.com: Having disconnected and labeled all the 12 V wiring, the 110 AC is now visable. It appears that all the AC ground wires (green) are run to a common buss. But , then, the AC Ground buss is connected with a 6 ga. wire to the DC negative buss. This doesn't seem right to me. Is it? They do this to insure your engine, underwater propulsion gear and everything hooked to the DC ground system is connected to every other stupid boat and the marina's big earth ground system, making one HUGE battery out of those zincs you can't figure out why they disappear so fast. There's absolutely NO reason why the independent DC system should be connected to the AC ground bus I know of. Ours isn't. I'll be damned if I'd pay with MY zincs to protect your prop because my zincs are hooked through the AC wiring ground to your zincs..... Oh, hooked up like that, too, your zincs are protecting the whole electrical system of HIS marina any place it touches the water or makes contact with the earth. Aren't you being, inadvertently, nice....(c; |
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Larry, it is quite difficult to prevent your "independent" DC system
from being connected to the AC ground bus. Like it or not, it is probably connected through the water, providing an opportunity for a potential difference between your DC ground system and the grounded case of an AC appliance. An improperly wired boat in the next slip can cause real safety problems aboard you vessel. You can safely isolate your system from the galvanic couples you fear with an isolation transformer or a galvanic isolator. I know you are well aware of both. You can also isolate your underwater metal (prop, shaft, etc.) from both the AC and DC ground systems, which may be what you meant to suggest. Chuck Larry wrote: Marc wrote in news:ufm1p1h2l7qr8s8vs3vbso6j1so1l3apgr@ 4ax.com: Having disconnected and labeled all the 12 V wiring, the 110 AC is now visable. It appears that all the AC ground wires (green) are run to a common buss. But , then, the AC Ground buss is connected with a 6 ga. wire to the DC negative buss. This doesn't seem right to me. Is it? They do this to insure your engine, underwater propulsion gear and everything hooked to the DC ground system is connected to every other stupid boat and the marina's big earth ground system, making one HUGE battery out of those zincs you can't figure out why they disappear so fast. There's absolutely NO reason why the independent DC system should be connected to the AC ground bus I know of. Ours isn't. I'll be damned if I'd pay with MY zincs to protect your prop because my zincs are hooked through the AC wiring ground to your zincs..... Oh, hooked up like that, too, your zincs are protecting the whole electrical system of HIS marina any place it touches the water or makes contact with the earth. Aren't you being, inadvertently, nice....(c; |
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"johnhh" wrote in
: So are you complaining that the AC ground and DC negative are both connected to the boats ground "Boats ground"? What's that? The boat is made of PLASTIC, an insulator. It has no "ground". It has a negative battery bus. It has an AC supply ground connected to the shore power ground system. What's the "boats ground"? I hear this a lot. It doesn't exist. The battery negative bus has no relationship, whatsoever, to the AC shore power ground as the two systems are totally isolated from each other unless there is something wrong with your battery charger, dual-voltage fridge or other AC/DC components. Touching the AC shore grounded appliance, already hooked to AC shore ground, with one hand and touching the engine block connected to the sea and DC ground bus results in no hazard...unless the AC shore ground is defective PLUS the appliance or device is defective. Touching an AC grounded device with one hand and a defective 2-wire toaster with the hot lead of the AC line hooked to its metal case has the SAME SHOCK as touching the DC ground bus hooked to the engine block....unless, of course, the boat has a proper GFI that should, but is not, required aboard the boat....just like proper NEC-approved breaker panels are not. (A bunch of little plastic breakers on a plastic panel screwed into a flammable wooden box made of some exotic, expensive wood is NOT up to the National Electric Code of the USA or any country with any brains. AC and DC panels in boats are made that way to SAVE MANUFACTURERS MONEY. They are NOT "safe", from fire (flammable) or explosion (not sealed against fumes) at all! Ok, back to the buses connected together for some stupid reason..... If the DC bus hooked to the zincs by virtue of the DC bus being connected to the engine block....is connected directly to the AC bus ground back to shore power ground through the boat's impressive yellow shore cable, this connects the boat's zincs STRAIGHT TO THE BOTTOM OF THE HARBOR...not to mention every other boat wired this stupid way. YOUR zincs are hooked to HIS underwater metal parts through the common-connected AC shore power ground wires. So? What happens now?........(you ask)..... Ever notice the metal conduit hanging loose under every dock on every marina in the country? See how it hangs into the water? If I hook MY zincs to that metal conduit (by the AC shore power ground wire from the boat with the DC negative bus hooked to AC shore power ground), MY zinc will fizz away protecting the rotting plating on that sagging conduit, every little ground wire touching anything conductive hooked to the water, and even the ground rod back at the feed point from the power company! Isn't that nice of me? Is it any wonder some people are going through those amazingly-expensive zincs at an alarming rate in your marina? Zincs protect what they are CONNECTED to. They are a virual shorted battery, the zinc one plate, any metal part making connections with the water the other plate and seawater as the electrolyte. In order for the battery to DISCHARGE, eating the zinc, it has to have a DIRECT DC PATH from the zinc to that plate. Unhook the path, you've opened the shorted battery circuit. The only battery plate the UNHOOKED boat makes a battery with is the metal part the zinc is mounted on and is protecting, not every neighboring boat connected to the AC power shore ground. Every AC device in the boat, with, of course, the exception of insulated, UL-approved, appliances-electronics-doubleinsulated drills-etc....should be hooked for safety to the SHORE GROUND, to prevent the AC line from appearing on the metal cabinet parts of it. Of course, it would be nice if the damned AC panel, ITSELF, on pleasure boats were so connected. They're not. Look into the wooden box. Metal breaker panel hooked to green wire? Not most. If you disconnect the DC negative bus from the AC Shore Ground green wire, you measure the DC potential caused by the zincs...the electroplating voltage trying to destroy the zincs. It CAN'T have any AC voltage between the Shore Ground hooked to a ground rod somewhere and the DC ground bus hooked to the engine block....doesn't wash. |
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chuck wrote in news:haikf.8489$N45.4470
@newsread1.news.atl.earthlink.net: providing an opportunity for a potential difference between your DC ground system and the grounded case of an AC appliance. An improperly wired boat in the next slip can cause real safety problems aboard you vessel. Show me how. The water is earth ground, no matter how the joker's boat is wired next door. If he's wired wrong, the AC current through the water will trip the AC breaker on the dock. Try it. There is NO WAY for the guy's boat next door to raise the AC potential of the whole ocean up off the AC shore ground potential my fridge is connected to! He'd need a thousand amp breaker to raise it a tiny fraction. The shore power ground is hooked to the earth/seawater. |
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chuck wrote in news:haikf.8489$N45.4470
@newsread1.news.atl.earthlink.net: You can also isolate your underwater metal (prop, shaft, etc.) from both the AC and DC ground systems, which may be what you meant to suggest. No, I mean to completely separate the DC negative bus/engine block from the AC line Shore Ground bus.... There is no reason whatsoever for them to be connected together. The transformer in the battery charger isolates them. The case of the battery charger should be connected to the AC shore ground ONLY if it's made of metal, which it no longer is any more. The metal case, if it has one, of the AC/DC fridge should be connected to shore ground but NOT the battery negative bus, either.... Shhhh....don't tell anyone.....Lionheart's HOUSE batteries are NOT connected in any way to the STARTING battery's negative ground bus UNLESS you reach under the aft cabin bunk and throw the grounding switch to ON....allowing you to connect the house batteries to the engine for emergency starting or charging the house batteries off the starting battery's alternator in another emergency. Our house battery alternator is connected to the house battery negative bus....NOT engine ground because it's mounted to the boat on a separate bracket and uses a rubber belt. Zincs last YEARS, not months. Nothing on the house circuit connects to underwater that needs a zinc. There are no leakage paths....with even separate DC negative busses. Works great....(c; |
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(big snip)
There's absolutely NO reason why the independent DC system should be connected to the AC ground bus I know of. Ours isn't. One guy we know had a bozo miswire his shore cord, and while lying along side his engine, grabbed hold of an AC grounded appliance frame. A hearse was needed to transport him to the next event in his life. Many of you have seen this waiting to happen, and maybe turned a little skin into smoke. Electricity is not foolproof! Eat your zincs out! Lynn....... see these scars? |
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Larry wrote: chuck wrote in news:haikf.8489$N45.4470 @newsread1.news.atl.earthlink.net: providing an opportunity for a potential difference between your DC ground system and the grounded case of an AC appliance. An improperly wired boat in the next slip can cause real safety problems aboard you vessel. Show me how. The water is earth ground, no matter how the joker's boat is wired next door. If he's wired wrong, the AC current through the water will trip the AC breaker on the dock. Try it. Well, the classic example of this is when the guy on the boat next to yours uses a 2-wire AC cord on an automotive-type battery charger. The charger develops leakage between the hot AC wire and the 12 volt DC ground. Won't trip any breakers because the current is too small. The circuit could easily deliver 10 amps forever with nothing tripping. Remember that the breakers are sized to trip before the wire causes a fire; NOT before enough current has passed through a person to cause electrocution. We're not talking about someone savy enough to use GFCI outlets here which can detect small current leakages. Alternatively, an automotive-type charger is plugged into a makeshift extension cord with the hot and neutral wires swapped. No green wire at all. Even without a leakage or short, the hot AC wire is now connected directly to the neighbor's DC ground system to his propeller. Again, nothing trips because the path through the water to the AC system's ground/neutral junction is too high a resistance to carry 15 amps (or whatever the breaker is rated at) with 120 volts applied. Next, you grab your engine with one hand and open the door of your fridge with the other as you reach for a cold one and you receive an unhealthy dose of 60 Hz. There is NO WAY for the guy's boat next door to raise the AC potential of the whole ocean up off the AC shore ground potential my fridge is connected to! He'd need a thousand amp breaker to raise it a tiny fraction. The shore power ground is hooked to the earth/seawater. What happens, Larry, is that your fridge cabinet is connected to the green equipment grounding conductor and to an AC ground/neutral junction on land. Your engine is connected through the water to the hot AC wire on the neighboring boat. The voltage between those two pieces of metal could approach 120 volts. Even a zinc/copper galvanic couple will result in a measurable potential difference in seawater. No need for massive currents and no need to think in terms of raising the potential of the whole ocean. :-) Draw out the circut and it will pop right out at you. There are documented cases of swimmers and boaters suffering electrocution from these problems. How probable? Different subject. First let's establish how it could happen. Chuck |
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On 2005-12-02, Marc wrote:
Having disconnected and labeled all the 12 V wiring, the 110 AC is now visable. It appears that all the AC ground wires (green) are run to a common buss. But , then, the AC Ground buss is connected with a 6 ga. wire to the DC negative buss. This doesn't seem right to me. Is it? unless the positive bus is connected to your hull (engine block etc...), I see nothing wrong with grounding the negative bus -- Bye. Jasen |
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So you're saying not to ground the AC ground at the boat, but to rely on the
shore ground? Everything I've read says you must ground it at the boat as a safety precaution against faulty grounding at the dock. Did I misunderstand something? I can't (conveniently) isolate my house DC from ground since I have a non-isolated ground alternator. Don't SSB antennas need to be grounded? Do the radios isolate the antenna ground from DC ground? "Larry" wrote in message ... "johnhh" wrote in : So are you complaining that the AC ground and DC negative are both connected to the boats ground "Boats ground"? What's that? The boat is made of PLASTIC, an insulator. It has no "ground". It has a negative battery bus. It has an AC supply ground connected to the shore power ground system. What's the "boats ground"? I hear this a lot. It doesn't exist. The battery negative bus has no relationship, whatsoever, to the AC shore power ground as the two systems are totally isolated from each other unless there is something wrong with your battery charger, dual-voltage fridge or other AC/DC components. Touching the AC shore grounded appliance, already hooked to AC shore ground, with one hand and touching the engine block connected to the sea and DC ground bus results in no hazard...unless the AC shore ground is defective PLUS the appliance or device is defective. Touching an AC grounded device with one hand and a defective 2-wire toaster with the hot lead of the AC line hooked to its metal case has the SAME SHOCK as touching the DC ground bus hooked to the engine block....unless, of course, the boat has a proper GFI that should, but is not, required aboard the boat....just like proper NEC-approved breaker panels are not. (A bunch of little plastic breakers on a plastic panel screwed into a flammable wooden box made of some exotic, expensive wood is NOT up to the National Electric Code of the USA or any country with any brains. AC and DC panels in boats are made that way to SAVE MANUFACTURERS MONEY. They are NOT "safe", from fire (flammable) or explosion (not sealed against fumes) at all! Ok, back to the buses connected together for some stupid reason..... If the DC bus hooked to the zincs by virtue of the DC bus being connected to the engine block....is connected directly to the AC bus ground back to shore power ground through the boat's impressive yellow shore cable, this connects the boat's zincs STRAIGHT TO THE BOTTOM OF THE HARBOR...not to mention every other boat wired this stupid way. YOUR zincs are hooked to HIS underwater metal parts through the common-connected AC shore power ground wires. So? What happens now?........(you ask)..... Ever notice the metal conduit hanging loose under every dock on every marina in the country? See how it hangs into the water? If I hook MY zincs to that metal conduit (by the AC shore power ground wire from the boat with the DC negative bus hooked to AC shore power ground), MY zinc will fizz away protecting the rotting plating on that sagging conduit, every little ground wire touching anything conductive hooked to the water, and even the ground rod back at the feed point from the power company! Isn't that nice of me? Is it any wonder some people are going through those amazingly-expensive zincs at an alarming rate in your marina? Zincs protect what they are CONNECTED to. They are a virual shorted battery, the zinc one plate, any metal part making connections with the water the other plate and seawater as the electrolyte. In order for the battery to DISCHARGE, eating the zinc, it has to have a DIRECT DC PATH from the zinc to that plate. Unhook the path, you've opened the shorted battery circuit. The only battery plate the UNHOOKED boat makes a battery with is the metal part the zinc is mounted on and is protecting, not every neighboring boat connected to the AC power shore ground. Every AC device in the boat, with, of course, the exception of insulated, UL-approved, appliances-electronics-doubleinsulated drills-etc....should be hooked for safety to the SHORE GROUND, to prevent the AC line from appearing on the metal cabinet parts of it. Of course, it would be nice if the damned AC panel, ITSELF, on pleasure boats were so connected. They're not. Look into the wooden box. Metal breaker panel hooked to green wire? Not most. If you disconnect the DC negative bus from the AC Shore Ground green wire, you measure the DC potential caused by the zincs...the electroplating voltage trying to destroy the zincs. It CAN'T have any AC voltage between the Shore Ground hooked to a ground rod somewhere and the DC ground bus hooked to the engine block....doesn't wash. |
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chuck wrote in news:hAskf.8744$N45.1460
@newsread1.news.atl.earthlink.net: Next, you grab your engine with one hand and open the door of your fridge with the other as you reach for a cold one and you receive an unhealthy dose of 60 Hz. Wow...this scenario is pretty absurd, as I suspected, but I'll respond to these unlikely events, anyways. Point...there is NO PATH from your neighbor's boat prop to your boat prop as the water between the boats IS EARTH GROUND....seawater to earth, a great ground, even if it's a freshwater lake. The path from the neighbor's absurd boat, taking the least resistance, is from the boat into the conductive water to EARTH GROUND, back to the AC source. There is absolutely no path to you and your absurd fridge. Don't believe me, take ahold of the hot wire on the dock in one hand and simply touch your finger to the water with the other. After picking up from the deck, unplug the boat and try it again to see if there's more current...There's not. You talk as if your neighbor's prop is only connected to your prop, which just isn't so.... AS to the breaker trip. If you connect AC hot to the engine block in his boat in seawater, I'd bet 50A would be just EASY! Seawater is a GREAT conductor. Fresh water is a fair conductor. Try it yourself. Simply drop the open plug from your boat into the water with the dock breaker turned on. There'll be a little buzzing underwater before the breaker overheats....and it eats the guts right out of the plug.... |
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chuck wrote in news:hAskf.8744$N45.1460
@newsread1.news.atl.earthlink.net: What happens, Larry, is that your fridge cabinet is connected to the green equipment grounding conductor and to an AC ground/neutral junction on land. Your engine is connected through the water to the hot AC wire on the neighboring boat. The voltage between those two pieces of metal could approach 120 volts. Even a zinc/copper galvanic couple will result in a measurable potential difference in seawater. No need for massive currents and no need to think in terms of raising the potential of the whole ocean. :-) Negative. The green wire is connected to EARTH GROUND. The engine is connected to EARTH GROUND, too! The seawater IS EARTH GROUND!....and a nice one it is. Your idea of floating the ocean 120VAC above that grounded fridge cabinet just isn't gonna happen.... Hook a big ground symbol to the prop...That's the circuit.... Here, a much safer test. Plug the boat into the dock but leave the other end unplugged from the boat. (leave the breaker off to be safer as we're fooling with ground, not AC. Measure the resistance from the engine block in the boat to the ground in the dropcord to the dock ground. Unless you have a rubber shaft coupler somewhere...you'll find the resistance VERY low through the water....salt water. Still think the engine isn't grounded through the underwater metals? Turn on the breaker and touch the black hot wire to the engine block and tell me how big an arc it draws for you. Be careful the melting black wire doesn't burn you....ok? |
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chuck wrote in news:hAskf.8744$N45.1460
@newsread1.news.atl.earthlink.net: There are documented cases of swimmers and boaters suffering electrocution from these problems. How probable? Different subject. First let's establish how it could happen. Chuck Swimmers are electrocuted from being in the current path from his prop to the bottom of the water. They're actually inside the conductor. Measure the AC voltage from your engine block to the ground wire to the dock....It's zero....(sigh) |
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"johnhh" wrote in
: So you're saying not to ground the AC ground at the boat, but to rely on the shore ground? Everything I've read says you must ground it at the boat as a safety precaution against faulty grounding at the dock. Did I misunderstand something? The boat is made of PLASTIC. You cannot ground the fiberglass. If you have a steel hull, I still wouldn't connect the green wire to it. It is already "grounded" through the seawater. You'd just add to your galvanic action problem. You may not be able to isolate it as the grounded equipment is hooked to the hull in lots of places, anyways. Fiberglass boats are being discussed. All AC grounds are to be connected to shore power "ground". This insures you get knocked on your ass if you touch AC hot and the grounded fridge case. But, that's the way they want it. Buy a plastic cased fridge, problem solved. The battery charger should have its DC circuit isolated from its AC circuit. If it's not, I wouldn't buy it. The + and - charging terminals should be totally isolated from the power-line- grounded case. If you tie the "faulty ground" at the dock, let's say it's open from corrosion or the wire is busted, connected or not to DC ground in the boat...it's still open. If the plug is wired wrong, the AC box is still grounded to ground. You'll get knocked on your ass plugging your grounded plug in if it doesn't explode in your hand before the breaker trips. Grounding the hot AC line through the faulty hot-connected-to- green-wire-to-the-boat absurd scenario in the DC to AC interconnected ground scenario only results in a big flash as the AC current has a direct path to ground through the engine block/propshaft, tripping the breaker I hope unless some other absurd scenario has it bypassed.... I'll be absurd, too. Every boater should have a ground detector built right into the AC breaker panel! |
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On Sat, 03 Dec 2005 18:54:28 -0500, Larry wrote:
"johnhh" wrote in : So are you complaining that the AC ground and DC negative are both connected to the boats ground "Boats ground"? What's that? The boat is made of PLASTIC, an insulator. It has no "ground". It has a negative battery bus. It has an AC supply ground connected to the shore power ground system. What's the "boats ground"? Not everbody has a "Tupperware" boat Larry. Some of us have steel boats. I sincerely hope that your philosophy changes for these. The best problem that I found on a boat was the following. Steel boat in at a dock connected to 240v shoreline. Boat was pressure washed and sparks were seen when the lance touched the hull. I was asked to check it out. Finally found that the hull was sitting at 24v dc above shore ground. Went searching and found that the metal end cover on the charger was touching an uninsulated crimp lug. The DC -ve was not connected to the hull. If the system had been installed correctly this would not have happened. I am glad that my Steel hull was not mored nearby!!! Richard Nb "Pound Eater" Parkend G+S |
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Larry, I think your conclusions are based on some incorrect assumptions
regarding the path resistances through earth and water. The beginning point of disagreement may be your assertion that seawater is a great conductor. Compared to copper, seawater is a terrible conductor: orders of magnitude worse, in fact. I admit it is not easy to do actual calculations on the resistance of a particular seawater path using specific electrodes, since path resistance will depend on surface areas of the electrodes and the distance between them, in addition to the resistivity or conductivity of the seawater. But the concept should be clear. At 120 volts, a 50 ampere circuit would require a path resistance of 2.4 ohms. There is no way you can find a six foot path from your prop to the earth below back to the ground/neutral AC connection point with a resistance of 2.4 ohms. Even if the water path resistance were zero ohms, (which would be low by some orders of magnitude) the earth itself will constitute more than 2.4 ohms resistance. I would not advise you to do this with 120 volts, but with a 6 volt transformer, connect one side to your prop and the other side to your green AC grounding conductor and measure the current and calculate the resistance of the path. The path will be from the transformer to your prop through the water to the earth through the earth to the ground/neutral connection point and then back to your transformer through the green grounding conductor. Tell us what you find. So even if the path resistance through the water from your prop to the prop in the next slip is an order of magnitude greater (quite unlikely) than the path resistance from his prop back through the earth to the ground/neutral connection point, there will still be a voltage between your prop and green grounding wire on your boat (which has negligible resistance back to the ground/neutral connection point). It is quite possible that the path through your prop and green grounding wire will have lower resistance than the path from the neighbor's prop through the water and the earth. Bottom line: what you have is an AC voltage connected to two parallel resistances. But the key point is that these resistances are sufficiently high that when a human body's resistance is added in parallel with them, enough current will flow through the body to cause electrocution. FWIW, I think you are attempting to apply electrostatics principles to this situation. It is quite true that if you have an object with a net positive or negative charge and touch it to earth (or water) that net charge will dissipate through the earth (or water). That simply doesn't happen here. If you apply a voltage to two electrodes stuck in the earth (or the water) you will find that depending on the parameters mentioned above, a finite resistance is encountered. Place the human body's resistance in parallel with that resistance and some current will flow through the body. Not telling you a thing here, Larry, just that the issue is really the magnitudes of the path resistances involved. Even at RF, seawater does not offer anything close to a zero ground loss resistance. Depending on a lot of things, some radial systems on earth are actually far better largely because of water's relatively lower conductivity. The confusion over the properties of seawater at RF arises from the fact that refelctions from seawater are far superior to reflections from any known earth types and this superiority is sometimes incorrectly transferred to seawater's performance as a ground plane. But that's for a different time. Regards, Chuck Larry wrote: chuck wrote in news:hAskf.8744$N45.1460 @newsread1.news.atl.earthlink.net: Next, you grab your engine with one hand and open the door of your fridge with the other as you reach for a cold one and you receive an unhealthy dose of 60 Hz. Wow...this scenario is pretty absurd, as I suspected, but I'll respond to these unlikely events, anyways. Point...there is NO PATH from your neighbor's boat prop to your boat prop as the water between the boats IS EARTH GROUND....seawater to earth, a great ground, even if it's a freshwater lake. The path from the neighbor's absurd boat, taking the least resistance, is from the boat into the conductive water to EARTH GROUND, back to the AC source. There is absolutely no path to you and your absurd fridge. Don't believe me, take ahold of the hot wire on the dock in one hand and simply touch your finger to the water with the other. After picking up from the deck, unplug the boat and try it again to see if there's more current...There's not. You talk as if your neighbor's prop is only connected to your prop, which just isn't so.... AS to the breaker trip. If you connect AC hot to the engine block in his boat in seawater, I'd bet 50A would be just EASY! Seawater is a GREAT conductor. Fresh water is a fair conductor. Try it yourself. Simply drop the open plug from your boat into the water with the dock breaker turned on. There'll be a little buzzing underwater before the breaker overheats....and it eats the guts right out of the plug.... |
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Jeez Larry, I didn't say anything about grounding anything to a plastic
hull. I also did not say that the AC ground should not be grounded at the shore side. I said that everything I have read says it should also be grounded at the boat end. Just like that grounding rod outside my wood house. "Larry" wrote in message ... "johnhh" wrote in : So you're saying not to ground the AC ground at the boat, but to rely on the shore ground? Everything I've read says you must ground it at the boat as a safety precaution against faulty grounding at the dock. Did I misunderstand something? The boat is made of PLASTIC. You cannot ground the fiberglass. If you have a steel hull, I still wouldn't connect the green wire to it. It is already "grounded" through the seawater. You'd just add to your galvanic action problem. You may not be able to isolate it as the grounded equipment is hooked to the hull in lots of places, anyways. Fiberglass boats are being discussed. All AC grounds are to be connected to shore power "ground". This insures you get knocked on your ass if you touch AC hot and the grounded fridge case. But, that's the way they want it. Buy a plastic cased fridge, problem solved. The battery charger should have its DC circuit isolated from its AC circuit. If it's not, I wouldn't buy it. The + and - charging terminals should be totally isolated from the power-line- grounded case. If you tie the "faulty ground" at the dock, let's say it's open from corrosion or the wire is busted, connected or not to DC ground in the boat...it's still open. If the plug is wired wrong, the AC box is still grounded to ground. You'll get knocked on your ass plugging your grounded plug in if it doesn't explode in your hand before the breaker trips. Grounding the hot AC line through the faulty hot-connected-to- green-wire-to-the-boat absurd scenario in the DC to AC interconnected ground scenario only results in a big flash as the AC current has a direct path to ground through the engine block/propshaft, tripping the breaker I hope unless some other absurd scenario has it bypassed.... I'll be absurd, too. Every boater should have a ground detector built right into the AC breaker panel! |
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OK Marc,
These are the facts: first,on your incoming shorepower ground,you would take care of any "stray current" problems caused by the marina or other boats by installing a galvanic isolator....sometimes called a zinc saver...almost all in-water boats made today have them installed OEM...Second, your AC ground absolutely SHOULD be connected to the DC ground buss, at 1 location only, to prevent ground loops....Why? Some of these other posters have forgotten that just because you are not connected to shore power,does not mean there is no AC power present....ie.gensets and inverters....A gfi will do absolutely nothing if there is no true earth ground, and if away from the dock, that ground is seawater,via the ship ground(shaft, bonding system, thru-hulls etc. Without that AC ground connection, you can become part of the ground circuit if a fault occurs. That said, you should have a seperate buss for each of the following: a neg. DC buss, a ship's GROUND buss, and an AC ground buss...Note that the DC neg buss is for connecting dc equipment to battery negative, the ship's GROUND buss is for bonding all equipment and machinery and the protective anodes together. Why connect the two? because in the event of a bad neg. DC connection, say to an engine block, it prevents The DC current from seeking an alternate path to the starter etc through seawater and the bonding system itself. Therefore there should be 1 bond between the neg DC and the ship's ground buss, and 1 bond between the AC ground buss and either 1)neg DC buss, or 2) (preferred) Ship's ground buss. This is not debateable or optional....it is absolutely necessary for safety...Period. If you have problems with rapid zinc consumption, you need to do a complete corrosion survey with the proper equipment to determine the source of the problem. Disconnecting the bond is like turning up the stereo to make an engine noise go away...Someone else remarked about the NEC and metal enclosures and sparks...He is wrong! each breaker IS ignition protected...they don't use metal enclosures due to weight and corrosion issues...This is a BOAT not a BUILDING, he needs to familiarize himself with ABYC and Lloyd's Standards, they are the applicable codes, and in almost all cases more stringent than the NEC.,but written for the marine environment, not sitting on a piece of dirt... Your SSB antenna better not be grounded or you'll cook your radio the first time you send modulation. SSB signals bounce off ground(called a counterpoise) which is seawater connected by an RF ground, your bonding and thru hull system, a steel hull, a metal fuel tank, or a dynaplate. This reflects the ssb signal skyward. Marc, do it once and do it right...remember that your boat is your total life support system when you're at sea... you can't walk out the front door when there's a problem....think about that before taking shortcuts or cutting corners to save money. And not to stir up things, but I can tell you with certainty.....Listen to Chuck, and forget anything that Larry posted....Chuck is right on target,and knows boats.....Guys like Larry are responsible for a large portion of my income... I have no problem correcting mistakes at $85.00/hour.. I'm not spouting steam at you, I have over 25 years in the marine industry primarily in electrical and electronics and plenty of schools and certs. It's cheaper to do it right! Good Luck! markvictor |
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Nice Post Mark. Thanks
"markvictor" wrote in message oups.com... OK Marc, These are the facts: first,on your incoming shorepower ground,you would take care of any "stray current" problems caused by the marina or other boats by installing a galvanic isolator....sometimes called a zinc saver...almost all in-water boats made today have them installed OEM...Second, your AC ground absolutely SHOULD be connected to the DC ground buss, at 1 location only, to prevent ground loops....Why? Some of these other posters have forgotten that just because you are not connected to shore power,does not mean there is no AC power present....ie.gensets and inverters....A gfi will do absolutely nothing if there is no true earth ground, and if away from the dock, that ground is seawater,via the ship ground(shaft, bonding system, thru-hulls etc. Without that AC ground connection, you can become part of the ground circuit if a fault occurs. That said, you should have a seperate buss for each of the following: a neg. DC buss, a ship's GROUND buss, and an AC ground buss...Note that the DC neg buss is for connecting dc equipment to battery negative, the ship's GROUND buss is for bonding all equipment and machinery and the protective anodes together. Why connect the two? because in the event of a bad neg. DC connection, say to an engine block, it prevents The DC current from seeking an alternate path to the starter etc through seawater and the bonding system itself. Therefore there should be 1 bond between the neg DC and the ship's ground buss, and 1 bond between the AC ground buss and either 1)neg DC buss, or 2) (preferred) Ship's ground buss. This is not debateable or optional....it is absolutely necessary for safety...Period. If you have problems with rapid zinc consumption, you need to do a complete corrosion survey with the proper equipment to determine the source of the problem. Disconnecting the bond is like turning up the stereo to make an engine noise go away...Someone else remarked about the NEC and metal enclosures and sparks...He is wrong! each breaker IS ignition protected...they don't use metal enclosures due to weight and corrosion issues...This is a BOAT not a BUILDING, he needs to familiarize himself with ABYC and Lloyd's Standards, they are the applicable codes, and in almost all cases more stringent than the NEC.,but written for the marine environment, not sitting on a piece of dirt... Your SSB antenna better not be grounded or you'll cook your radio the first time you send modulation. SSB signals bounce off ground(called a counterpoise) which is seawater connected by an RF ground, your bonding and thru hull system, a steel hull, a metal fuel tank, or a dynaplate. This reflects the ssb signal skyward. Marc, do it once and do it right...remember that your boat is your total life support system when you're at sea... you can't walk out the front door when there's a problem....think about that before taking shortcuts or cutting corners to save money. And not to stir up things, but I can tell you with certainty.....Listen to Chuck, and forget anything that Larry posted....Chuck is right on target,and knows boats.....Guys like Larry are responsible for a large portion of my income... I have no problem correcting mistakes at $85.00/hour.. I'm not spouting steam at you, I have over 25 years in the marine industry primarily in electrical and electronics and plenty of schools and certs. It's cheaper to do it right! Good Luck! markvictor |
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Thanks John,
I hate to see people get screwed up by bad info.. One of the most common things I hear on service calls is "my buddy hooked it up for me" or "my buddy said all I had to do was..." I hate to tell them, but he's not their buddy, he's MY buddy! Sad but true..... markvictor |
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In article .com,
"markvictor" wrote: Your SSB antenna better not be grounded or you'll cook your radio the first time you send modulation. SSB signals bounce off ground(called a counterpoise) which is seawater connected by an RF ground, your bonding and thru hull system, a steel hull, a metal fuel tank, or a dynaplate. This reflects the ssb signal skyward. I just wish that folks who give advice about MF/HF Radio Antenna Systems ACTUALLY knew what they were talking about BEFORE they posted extainious BS that has little basis in fact. Me |
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Well "me", since you are anonymous I can only assume you can't back
your play...Tell me where the antenna ground is on a longwire or a backstay. and tell me where the ground conductor is in GTO-15...do you know what that is? Or perhaps you are referring to the TUNER.... which IS connected to your ground... is that what "me" is thinking about? Perhaps I should clarify for you the difference between antenna and antenna system, would that make you feel better? Yes, I did simplify my explanation of counterpoise but that was not the issue at hand; the issue was grounding the antenna which I again will emphatically repeat IS NOT GROUNDED! If you don't accept this I dare you to take the insulators out of your backstay and show us what a little modulation will do....with your radio, of course,not mine...Ground your tuner?...Absolutely! ....Ground your antenna?....Not mine,thank you.... And FYI "me", I hold an F.C.C. General Radiotelephone Operator's License with endorsements, I am a certified bench tech and am working on my broadcast engineering cert. And you might want to use spell check...."extainious"??? This isn't Harry, is it? markvictor |
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I guess I was responsible for first saying 'ground the antenna.' I was
thinking the counterpoise and was sloppy in my terminology. I am strictly a novice, but I do know better than to ground the antenna itself just like I am not foolish enough to think I can ground anything to a plastic hull. John "markvictor" wrote in message oups.com... Well "me", since you are anonymous I can only assume you can't back your play...Tell me where the antenna ground is on a longwire or a backstay. and tell me where the ground conductor is in GTO-15...do you know what that is? Or perhaps you are referring to the TUNER.... which IS connected to your ground... is that what "me" is thinking about? Perhaps I should clarify for you the difference between antenna and antenna system, would that make you feel better? Yes, I did simplify my explanation of counterpoise but that was not the issue at hand; the issue was grounding the antenna which I again will emphatically repeat IS NOT GROUNDED! If you don't accept this I dare you to take the insulators out of your backstay and show us what a little modulation will do....with your radio, of course,not mine...Ground your tuner?...Absolutely! ....Ground your antenna?....Not mine,thank you.... And FYI "me", I hold an F.C.C. General Radiotelephone Operator's License with endorsements, I am a certified bench tech and am working on my broadcast engineering cert. And you might want to use spell check...."extainious"??? This isn't Harry, is it? markvictor |
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In article .com,
"markvictor" wrote: Well "me", since you are anonymous I can only assume you can't back your play... snipped for brevity And FYI "me", I hold an F.C.C. General Radiotelephone Operator's License with endorsements, I am a certified bench tech and am working on my broadcast engineering cert. And you might want to use spell check...."extainious"??? This isn't Harry, is it? markvictor Well as long as your looking to compare "Wall Paper", it would seem, your just a novice, in the Marine Electronics Field. I have held FCC licenses for over 40 years, both RadioTelephone and RadioTelegraph and First Class for both. I have an Aircraft Endorsement, as well as Sea Time Endosements on the Telegraph ticket, and Radar Endorsements on both. I have more time in the field of Marine Electronics than you probubly have been alive. I have worked for the biggest OEM in MF/HF Communications in the North Pacific, back in the day. Spent more summers, traveling in Alaska, doing radio system design and installation, and am the LAST of the Alaska Cannery Radiomen. I have been an FCC Resident Field Agent, and done more SOLAS Inspections of Title III Part II and Part III Vessels, than you have ever seen, let alone actually been aboard. I started my career in Broadcasting before switching to twoway, and left that field as Chief Engineer, of a 10Kw AM/FM Station, and that was back before anyone knew about SolidState Broadcast Transmitters, and folks dealt with REAL Big tubes and water cooled finals. The above doesn't include any of the Papers that I have around here somewhere, with NABER/PCIA Logos all over them, either. I have known and worked with the best MF/HF Radiomen in Commercial Service. These guys MADE MF/HF Communications. The likes of Ed Parsens, Dan Farley, Dick Stephens, Eddie Zanbergen, Len Miller, Don Hollingsworth Sr. & Jr., Bill Forgey, Bruce Gordon, Mac McPhereson, Billy Pulse, Mark Johnson, Ed Shilling, Dennis Seth, and many, many, more, over the years. Sonny, your a bush league'er, and not a very good one at that. When you figure out what a "Counterpoise" actually is, and does, and what the difference between it and RF Ground is, and why these are required for a Marconi Antenna to function, then maybe, if you can actually do the math required, to explain all the above to a High School Physics Class, THEN you will have made a, very small, dent in the Knowledge Base of RF Communications. Untill then, best you study and learn the basics of the field, you seem to have choosen for a career. Me just an "Old Fart" in semi-retirment........ |
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I humbly bow in respect to an old fart!
But your antenna is Still not grounded.... |
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Gotcha....
It sure has ruffled "me's" feathers... |
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Or would it be more acceptable if I said the radiating component of
your antenna system? |
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"markvictor" wrote in message oups.com... I humbly bow in respect to an old fart! But your antenna is Still not grounded.... I humbly bow in respect to an old fart! I think he's constipated. Happens sometimes when you get older. Makes a person snippy and ornery. |
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Counterpoise-an artificial substitute for earth, used to prevent signal
loss to "earth" and in essence reflecting signal to the hemisphere opposite "earth" and in an ideal wotld would effectively double the signal propagated to that hemisphere as compared to the hemisphere inclusive of earth; this not being a perfect world there is a loss to earth,but then we would be getting into wave theory.... I've seen all the fields you claim to be an "expert" in all over the usernet,which would have to make you,what, about 150 years old? You're a real candidate for Ripley's... I probably have more time on a marine toilet than you have on boats... I feel sorry for you, you tired and lonely old man.... On second thought, crawl back under your bridge, troll! |
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On Thu, 15 Dec 2005 20:03:00 GMT, Me wrote:
Me just an "Old Fart" in semi-retirment........ ===================================== And all the time I was thinking you were "Bruce in Alaska". |
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"Wayne.B" wrote in message ... On Thu, 15 Dec 2005 20:03:00 GMT, Me wrote: Me just an "Old Fart" in semi-retirment........ ===================================== And all the time I was thinking you were "Bruce in Alaska". And that, Marc, I hope answers the questions you posed to this experienced group! Old Chief Lynn |
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Yes, thanks to all , especially markvictor. Very lucid, concise and
unambiguaous. On Thu, 15 Dec 2005 21:06:22 -0800, "Lynn Coffelt" wrote: "Wayne.B" wrote in message .. . On Thu, 15 Dec 2005 20:03:00 GMT, Me wrote: Me just an "Old Fart" in semi-retirment........ ===================================== And all the time I was thinking you were "Bruce in Alaska". And that, Marc, I hope answers the questions you posed to this experienced group! Old Chief Lynn |
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I have been away for awhile so haven't read this group in some time.
Things haven't changed much. Still entertaining though. Seems like lots of hand waving and chest thumping going on in this thread. I suppose I can stir the pot a little too. The important thing you want to watch for in the bonding system of all items on the boat is that it should not carry any current anywhere. If it does then there can be a slight difference in voltage between grounded items and that will cause electrolysis of underwater items. This is where a single point connection between different grounds is important. I.e. bonding system, DC ground and AC ground. If all the underwater items are bonded together and only one point from that goes to the other grounds it will help eliminate the chances of there being any current through various points on the bonding system. And yes it is important for the AC system to be grounded at this point also. All metal items on the boat that have power to them should have a common ground to prevent shock in case of a fault in some item. While AC current does not cause electrolysis of underwater components, any DC current that may be carried on the AC line will. Some boats are wired with isolated systems to try and prevent electrolysis in that way. While some are successful most are not as it is almost impossible to maintain a system like that unless on a very small boat. One of the hand wavers made a comment about GFCI breakers not being effective without a ground. That is far from the truth as a GFCI does not depend on ground to operate. It looks to see if the the supply and return currents are equal between the hot and neutral lines feeding it. If they are not it will trip and open the circuit. If the currents are not equal in both wires that means that the current has found an alternate path other than the intended return wire. There were also some kind of silly comments made about not grounding the SSB antenna and signals bouncing off a counterpoise and ground and a counterpoise doubling the signal?? It is entertaining if nothing else. Regards Gary On Fri, 16 Dec 2005 13:56:33 -0500, Marc wrote: Yes, thanks to all , especially markvictor. Very lucid, concise and unambiguaous. On Thu, 15 Dec 2005 21:06:22 -0800, "Lynn Coffelt" wrote: "Wayne.B" wrote in message . .. On Thu, 15 Dec 2005 20:03:00 GMT, Me wrote: Me just an "Old Fart" in semi-retirment........ ===================================== And all the time I was thinking you were "Bruce in Alaska". And that, Marc, I hope answers the questions you posed to this experienced group! Old Chief Lynn |
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Read it agaln, Gary... it does not say the signal doubles, it is
doubling the signal radiated hemispherically opposite earth,as compared to a signal with no conterpoise to prevent signal propagation equally in all directions...in a perfect world...but not being perfect there is loss to grond depending on placement and conductivity vs. reflectivity, etc ..... and if you read the thread this whole life altering issue has mutated from a suggestion that one would not be well suited by grounding their backstay if using it as an antenna ================================================== ============ The most obvious effect is that the ground forces the antenna's radiation pattern to appear in the half-space above the ground. This is illustrated by comparing the radiation around a monopole fed against ground to that of a dipole in free-space. The monopole has twice the power in the hemisphere above the ground compared with the power in either hemisphere of symmetry for the dipole in free-space. ================================================== ============= |
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So as you are saying, a dipole element has no counterpoise? A vertical
radiates twice as much as half a dipole? The vertical element radiates half the power and the ground radiates the other half? "hemispherically opposite earth". Now I wonder what that one means? Grounding the back stay will cause it to not radiate if using it as an antenna? The hand waving goes on although it seems a little more vigorous. I don't know how you worked all that into a question about wiring but maybe you want to check some of your references again as to how things work a little. And yes I did read most of the thread. Quite amusing. I have no clue what you are trying to say and I am sure many others also don't. Regards Gary On 16 Dec 2005 19:04:43 -0800, "markvictor" wrote: Read it agaln, Gary... it does not say the signal doubles, it is doubling the signal radiated hemispherically opposite earth,as compared to a signal with no conterpoise to prevent signal propagation equally in all directions...in a perfect world...but not being perfect there is loss to grond depending on placement and conductivity vs. reflectivity, etc .... and if you read the thread this whole life altering issue has mutated from a suggestion that one would not be well suited by grounding their backstay if using it as an antenna ================================================= ============= The most obvious effect is that the ground forces the antenna's radiation pattern to appear in the half-space above the ground. This is illustrated by comparing the radiation around a monopole fed against ground to that of a dipole in free-space. The monopole has twice the power in the hemisphere above the ground compared with the power in either hemisphere of symmetry for the dipole in free-space. ================================================= ============== |
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Only the clueless hav no clue...
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I repeat "Read it again, Gary." the example I gave is an
illustration......read what it says and apply your thought process instead of your reactionary ....If you did read the thread you would know where the question developed...or perhaps you can find someone to read it to you so you don't miss anything,since you admit in your post that in fact you have not read it all. And FYI, the illustration I used is derived from Ralph Holland's Amateur Radfg 1996 .... |
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hemisphere=half-space
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