Electrically Grounding the Boat

[Elcoholic]

Well, since I can't seem to get the search engine to work, you'll have to endure another stupid question from a novice.

I have never had to ground a boat before. It's just never been an issue and something to which I have never given much thought. I have just installed a generator that will be delivering 24KW at 230 volts. This seems like a good time to start thinking about grounding the circuit.

So, gentlemen, how's it done?

[Bob Cleek]

What in God's name do you need a 24KW 230VAC genset on a boat for? A ship, maybe! LOL The answer is pretty simple, if a ground is needed, you can tie into a keel bolt if you have a ballast keel, or if not, install a grounding plate on the bottom and tie into that. Grounding plates are a stock chandlery item. HOWEVER, if I were you, and I've been doing boat work all my 55 years, I'd consider this one a job for a professional. Find a qualified marine electrician to inspect your installation and advise you whether grounding is needed or advisable. Grounding can do more damage to a boat than not in some cases. DON'T DO THIS JOB YOURSELF! Even if you know what you are doing, if you hire a pro you'll at least have somebody to sue when somebody gets killed by it on board!

[Gary E]

EXACTLY what Bob said... EXACTLY....

and on my other pc is a helpfull link that I will post later today...

[Noah]

A great book to learn about these things is Nigel Calder's "Boatowner's Mechanical & Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems"

http://www.amazon.com/exec/obidos/tg/detail/-/007009618X/ref=pd_sim_b_1/002-5374739-6709629?%5Fencoding=UTF8&v=glance

[Thad Van Gilder]

I agree.
I fix everything, but...
That's a job for the friendly nieghborhood electrician.

-Thad

[WoodenBNut]

"Marine Electrical Installation" by John Piper is a good book too. Yeah - careful is the word when working with AC/grounding and even DC on a boat. Lots of stuff can go wrong.
My 1964 Chris 35' Sea Skiff had a copper ground plane on the white oak keel of this boat. These old ground planes were used to ground the old marine AM radios (before VHF). Well anyway, someone screwed up the grounding to the copper ground plane on the keel and hooked it up to the engine alternator!! (off of what looked like an alternator condensor/noise supressor). Anyway, this error somehow sent an electric current through that ground plane and the result over the years that it was hooked up this incorrect way was to delignify - electrolysis to some of the wood in the keel. It turned some of the keel white oak wood white and crumbly. It was not your typical wood rot - it was due to improper wiring.
I removed the copper ground plane - but the damage was already done. Lot of work to repair.

[Elcoholic]

The 24KW generator head is needed to power the 220V four-burner electric stove, ice maker and hot water heater, 110V microwave, wine chiller two refrigerators, freezer, outlets and lighting circuits. I guess it also serves to amuse Bob Cleek.

Thanks for your help.

[Gary E]

Elco,
The more I think about your question as posted here, I ask myself, why would he ask?.. My conclusion may be wrong and if it is I apologize in advance. So here's what I think, If you know something about electrical systems, you'd not bother to ask a buncha people that may or may not know squat about it, and finding advice about how to install this generator and a electical control pannel is nigh on to imposible on the internet and following said advice is just plain NUTZ... So, with regard to the above mentioned regard to ground plates, yes that true,,,BUT... YOUR need is to get YOUR generator installed and working properly and SAFELY, therefore forgit the books, there not wrong, but they are NOT for YOU NOW...the only thing I would do is take that walk down to the comercial docks and ask the guys that have this sorta equipment running now and ask them for recomendatios for a competent man to do the job...

Sorry if this sounds heavy handed, but ya dont dick with 240V electical generators unless you know EXACTLY what your doing.

Good Luck

[Elcoholic]

I appreciate all the well-meaning comments. However, I already KNOW that 240V current, or even 110V for that matter, is dangerous if not grounded properly, especially in a water environment.

I was looking for some advice from someone who HAS 240V aboard a wooden vessel...advice in the form of grounding plate dimensions, wire sizes, mounting procedures, location, possible zinc protection, etc.

It can and has been done but if you don't have it or have not installed it, then I doubt that you know any more than I do, particularly since I am a licensed electrician. Inferring that I'm some sort of lunatic defeats the purpose of the forum. Please....no more "help."

[George Roberts]

Elcoholic ---

You wrote "However, I already KNOW that 240V current, or even 110V for that matter, is dangerous if not grounded properly, especially in a water environment."

Grounding or not grounding will not hurt you or anything else on the boat. (Aside from grounding multiple engine blocks...)

What will hurt is current running through your body (or the wood of your boat).

I would suggest you find someone who knows current practice in this area so that if the the equipment needs to be worked on in the futuer no one will be surprised.

[ssor]

Elco,
Since you are an electrician you know or should know that the wire size for each circuit is determined by the rating of the circuit breaker. You also know that you could "float" the entire system. Grounding is essential with commericial power systems because the supplier has already grounded the center tap on the transformer. I understand that this will be a vessel used for carrying paying passengers and therefore the insurance companies and the coast guard will require compliance with all of the applicable codes.
As has been previously stated this is not the proper source of information for a job that carries this level of liability.

[Gerald]

There has been a number of people that have written about the subject of grounding and wiring in the metal boat forum. We probably don't need to be reminded that wooden and metal boats face different kinds of problems!
http://www.metalboatsociety.com/
I will be placing a 8KW unit in my boat and face the same problems you do. Lucky for me that 8KW unit won't kill me near as dead as your 24KW unit. The question might come up why I need a 8 KW unit in a 39' boat? However, that question should be proceeded by where are you going?
BTW if you have a good field controlled voltage regulator schematic for a 8KW unit I would sure be interested. I am currently controlling 220 manually.
Good Luck
Gerald

[Gary E]

particularly since I am a licensed electrician. Elco,
Now at this late stage you claim to be a electrician, the very first question you asked here is asking for trouble since you should know damn well more about this subject than most.

One more question, since you intend to carry paying passengers, is this to be a Coast Guard Inspected Vessel?

[Elcoholic]

My original question was poorly worded. I need SPECIFICS, particularly having to do with the the surface area of the copper buss plate. @200 inches of surface area is standard for homes. (5/8" rod driven into the ground 8') So, specifically:

Does anyone KNOW the surface area required for the grounding buss on a wooden boat using a 24KW, 240V, 200 amp generator head?

Does anyone KNOW if/how this buss should be insulated from direct contact with the wooden hull?

Does anyone KNOW if zincs should be employed directly on the buss?

My electrical license is for residential contracting. It is not a Ph.D. I have ZERO experience grounding a wooden boat. It must be done right and I have yet to find a reliable source of information. This forum was one of many avenues I have been exploring. No, I was not "asking for trouble", I was asking for help. If your intention is to criticize and/or ridicule my intentions and motives, just shut up. There are a few jerks here with attitudes. Try to avoid the urge to stand up and be counted.

[ssor]

When I wired Bietzpadlin for shore power I gave serious consideration to installing an isolation transformer and floating all of my house wire keeping everything above ground but isolated from ground. If you are producing your own power than you can run your ground bus to the generator and keep neutral separated from ground just as you do with a GFCI. But if you should tie into shore power then you must follow the rules of the power company.

Edited to add: Is "neutral" on this generator grounded? Are both output wires hot with respect to ground?

[ 06-09-2005, 12:03 PM: Message edited by: ssor ]

[paladin]

Elco....you don't need to "Ground" the system. So called grounds etc on the hull of the vessel are not for 'grounding' the electrical devices, they are there as metal masses to act as a counterpoise to your radio systems, in particular, the high seas single sideband radio systems...
if your alternator is isolated, you could get away with isolated wiring although I'm a coward and would use a 1:1 isolation transformer. If wired to code the color code for marine electrical wiring is not the same for shore based homes etc, so I would not hire a local electrician unless he was a marine specialist. there's lotsa difference to marine wiring, not only color code, but wire size, current drop in the wire length, startup loads.....so do it right..
edited to add...a proper crimp joint is important and cannnot be done with el cheapo hand crimpers. Mine are mil-spec and cost close to a grand each, so the dude you hire will have all the right tools.

[ 06-09-2005, 01:10 PM: Message edited by: paladin ]

[Gary E]

Originally posted by paladin:
Elco....you don't need to "Ground" the system. So called grounds etc on the hull of the vessel are not for 'grounding' the electrical devices, they are there as metal masses to act as a counterpoise to your radio systems, in particular, the high seas single sideband radio systems...You dont?... let me ask you about what happened a long time ago, maybe it's relevent, maybe not.

A long time ago, before todays typical 3 wire appliances, We are on vacation in Fla, making toast while barefoot in the rental house. Touch the toaster and get a shock not a full blast just a tingle. Dad simply reversed the plug in the wall and all was fixed.

Now we both know why that worked then, but what about an isolated not grounded electrical stove in his galley, you are barefoot and grounded because you are touching somethng else, or even a wet or damp rug. Now what happens if something goes haywire in that stove and you touch it?

eddit,,,
yeah, that radio needs a ground, and even VHF radios work better with a ground, I dont know why.

[ 06-09-2005, 02:06 PM: Message edited by: Gary E ]

[ssor]

You received an electrical shock because the power company grounds the center tap on the tranformer,(thus the two insulated wires and the bare cable carrying the power into the house. 120 volts from each insulated wire to the ground wire and 240 accross the two insulated pair.In water heaters 240 volts is brought to the heating element and the tank is grounded. Old 120 volt appliances had one side of the power supply tied to the chassis or frame of the appliance, if by chance the "Hot" wire were connected to the frame then the wooden or concrete floor and your bare feet would make you a part of the electrical circuit when you touched any metal parts. Now we have one prong fat and one narrow to prevent connecting improperly. The round prong on three wire plugs is tied to the ground wire which is the bare wire in the house wiring cable and is connected to the ground buss in the fuse or breaker box. This ground bus is connected by heavy solid copper wire to a copper clad rod that is driven into the soil. At the power pole there is also a rod driven into the soil that connects the center tap on the transformer to ground. The whole purpose of this is to eliminate the risk of accidently taking the output from the transformer to ground. The white wire in house wiring cables is the neutral and is usually carried to the ground buss. When a Ground Fault Circuit Interrupter is installed the white wire is carried to internal circuitry that senses that current in the "hot" wire and compares it to the current in the neutral wire and the ground wire. In a properly functioning circuit all of the current in the "hot" wire is carried by the "neutral". Should the difference exceed 5 miliamps then the Interrupter functions and breaks the connection.

[Gary E]

ssor,
yes, you explained the house in Fla very well....

But you did not address the boat question

[Tom Jackson]

This may not apply directly to your question, but anyone working with electrical systems in wooden boats should pay attention to the issues involved with "bonded" systems. See USCG N-VIC 7-95, at this link: USCG NVIC 7-95 (http://www.uscg.mil/hq/gm/nvic/7%5F95/n7%2D95.htm)

[ssor]

With the boat you need to use the chassis of the generator set as the ground point for all your electrical circuits. But as I said in an earlier post on this thread if you connect to shore power then you must follow the rules for shore power on boats because the whole world is a part of the ground circuit for the commericial power grid.

[Gary E]

ssor,
"With the boat you need to use the chassis of the generator set as the ground point for all your electrical circuits."

Does the following comply with your above statement and what will happen if the boats generator is or is not connected to the earth ground or a ground plate on the boat's bottom?

Certanily someone having this system on board will connect to shore power.

but what about an isolated not grounded electrical stove in his galley, you are barefoot and grounded because you are touching somethng else, or even a wet or damp rug. Now what happens if something goes haywire in that stove and you touch it?

[ssor]

Earlier Paladin and I mentioned the use of isolation transformers for powering boats. The purpose of this is to completely isolate the surroundings from the power supply. With an isolation transformer it is safe to touch one of the output leads if the other lead is not connected to anything else that you are in contact with(like a bird on a wire). If there is no path for the current to return to the source except for the wire then touching the stove will be harmless. If it is not harmless then there will exist an accidental path for the current. It is for this reason the the power companies, the electrical workers, and the engineers have standardized the method for generating, transmitting and using electrical energy. When you consider that the entire North American power grid is interconnected and functions very well then you must realize that this stantard has to be adhered to at all times if you intend to share it.
If you decide to wire your boat with DC power you still find that the makers of the power generating equipment have set down some rules that you are stuck with. Like Positive or Negative ground on the alternator.

[Gary E]

But you still avoid ansering this....

but what about an isolated not grounded electrical stove in his galley, you are barefoot and grounded because you are touching somethng else, or even a wet or damp rug. Now what happens if something goes haywire in that stove and you touch it?

eddit,,,
Let me make it ever easier,,,

His generator is mounted on insulated mounts,
No connection to the engine or the battery
All wiring is so the current path is from the generator to the circuit breaker pannel to the stove and back to the generator,

In other words...NO GROUND to the water...

[ 06-09-2005, 04:22 PM: Message edited by: Gary E ]

[WoodenBNut]

Like most of you said - this is a very complex and difficult subject. You essentially are going to have a mix of 110V Shore Power (30 or 50 amp service), A generator putting out 220V - split down to available 220V & 110V circuits. you could even throw in a battery charger and maybe an inverter if you wanted too. This can all be done, and you will have different grounds and gound points depending on what your current source of electric power is at the time. If your source is 110V Shore Power, you will be switched to running Shore Power and you will have that circuit connected and that ground point. THIS IS ALL DONE THROUGH AN ELECTRICAL SWITCH SETUP (some are manual and some are automatic - depending upon what you install). And you had better not have (say) Shore power and say the Gen Set connected up and going of the same circuit at the same time --- or that will produce some interesting results you don't want to happen - lots of sparks and fire. Yes, this is an area best left to experts in the field and someone who has had experience in working with these complex circiuts. It is much more complex than any home electrical circuits.

[ssor]

If the stove is truly isolated and the power source including its chassis is not electrically connected to the structure you are standing on, and one leg of the output of the generator is connected to the frame of the stove you won't be harmed. There is an easy way for you to see this for yourself, with a multimeter insert one probe into an outlet and read the voltage, next place the other probe on the kitchen sink and read the voltage,next place the probe into the other slot on the outlet and repeat the first two steps.

[kulas44]

Electrician here, wireman, lineman, rated for 138kv barehanded,(no, I'm not insulated) commercial, residential, oilfield, every certification, 15 years doin it. owned boats for 20 years. I have to much time on my hands today and it's hot outside. My advice, nothing that is in contact with the water should be connected to the green case wire, and get an isolation transformer.

[Puka]

Question for Ssor:
Why don't boats have RCD's (Ground Fault Circuit Interrupters) on all grounded circuits as a mandatory requirement? They are required here for all domestic intallations.Then you only get <15mA
for a few ms's ;)

Also,how does all this relate to a mast lightning
strike. Isolating, expensive electronic circuitry obvously is a must.

As an after thought, I guess if RCD's were used they would spend most of there time triggered,through residual tracking. (saltly atmosphere)Perhaps an RCD with a higher trigger?

[ 06-09-2005, 06:35 PM: Message edited by: Puka ]

[Bob Cleek]

Elco, let me say that the answers you initially received would have been more specific had your question been better asked. That said, you seem to have a chip on your shoulder, which wouldn't bother me in the least, save that the sort of chip you are sporting could cost you, or someone else, their life.

Remember, all the grounding in the world isn't going to amount to a hill of beans when your boat's taking on water and you're standing in the engine compartment with water up to your ankles trying to get that 220VAC generator to power your pumps.

There ARE a number of marine electrical codes in existence. If you are intending to obtain a passenger license for your boat, you will run into the Coast Guard's version. If you plan to insure your boat, you will run into the NFPA code, among others. Google the topic and you will find much information. Try this site for openers:

[URL=http://www.tc.gc.ca/MarineSafety/TP/Tp127/essential.htm]http://www.tc.gc.ca/MarineSafety/TP/Tp127/essential.htm[/UR L]

Section 52.2 of the above code tells you how big your grounding plate must be, together with all details required for installation.

Let me add some further observations. Forgive me if I'm telling you something you already know. Maybe somebody else here doesn't and it could be helpful to them, if not you.

You mention a number of appliances you plan to run on your boat. Are they MARINE certified equipment or residential equipment? This is critical, especially in a 220VAC environment. Your wiring should be marine grade. This means individual tinned strands so that there will be no breaks in the wire resulting from vibration. Individual tinning prevents the corrosion in the marine environment from turning standard copper wire to dust pronto. As Paladin said, you must also pay particular attention to your connection system.

If you are not using a marine stove or reefer, you can expect that in a very short time these will malfunction due to corrosion. That usually manifests itself first in short circuits, which are very dangerous in the marine environment.

Also, are you intending to install a 12VDC system as well? If not, you face the prospect of running you generator continuously, which, fuel costs aside, isn't going to make you particularly welcome in quiet anchorages and harbors.

Don't bother to argue with whatever good or not so good advice you find here. Go check the codes. As a journeyman electrician, you know this is the way to go. If you have further questions, you might consider hiring a qualified marine surveyor to advise you. When you insure the vessel, or seek passenger licensing, you will have to face a survey in any event. Better to know the requirements before you have to re-do work.

[ 06-09-2005, 06:39 PM: Message edited by: Bob Cleek ]

[Gerald]

>>>>If you are not using a marine stove or reefer, you can expect that in a very short time these will malfunction due to corrosion. That usually manifests itself first in short circuits, which are very dangerous in the marine environment.<<<<

I went to the boat show a few weeks ago. While looking at refrigeration units I ask the salesperson what the difference was between the compressor in my fridge at home at his veeery high priced unit. He stated that the compressor in my home unit would only last a year in the marine environment and his would last next to forever. My 220 volt home unit has two wires entering the compressor housing and the rest is sealed. The salesman couldn't tell me why his would last longer so I am hoping someone here can? If it is the two wires entering the compressor that will fail then I am sure some liquid rubber could seal it well enough to keep out the marine environment.
Gerald

[kulas44]

I recently removed a home type refridgerator from a 1972 model boat. The boat lived in Florida most of its life. The paperwork for the warranty showed it to have been installed in 1973. It was still working. I have a 1979 44 ft. sportfisher with the orginal west-of-the-house fridge freezer that works like new. Countless trawler owners have home type units, haveing given up on MARINE (pronounced overpriced) units. You can find some really good buys on stainless under counter units now. Sometimes marine spec is good, sometimes it is bs.

[kulas44]

As for everyone being scared of 240 volt, it's just a pair of 120's, without a ground, as for haveing a big genset, 24kw ain't that big, and no, you do not need to connect the neutral to the genset frame, only to the centerlug from the windings. All of this is so simple that only the uneducated could debate it. Lightening protection and overcurrent protection are the only issues that need to be addressed. Overcurrent protection is via the unobstructed green wire (hence the stipulation in the code that nothing be connected to it). Lightening protection must be seperate from all else. If desired you could use diodes for the small devices and a ground/neutral overvoltage shunt for larger items if you felt the need.

[ssor]

[QUOTE]Originally posted by kulas44:
[QB]As for everyone being scared of 240 volt, it's just a pair of 120's,

Until you have been standing in a puddle and gotten across 120v AC you can talk all you want about it being ONLY 120Volt ac And a .44 mangleum is just a gun. The damn stuff will kill you and your widow can tell the world that it was ONLY 120 volt ac.

[kulas44]

Agreed, and in some circumstances 32 volts dc would be deadly. Any A.C. voltage that is useable by modern appliances can kill you. Thats not the point. The jist of the ? was how much ground surface (as compared to the ground rod at your house) does he need for his boat. Knowledgeable sailboaters would be more able to answer that as there need for lightening protection is greater. Just like your home copper plated 8 foot ground rod is no more a reliable "ground" connection than a large copper plate under your boat, it is ultimately only needed to dissipate a static high voltage overload (lightening) without which the charge will be dissipated through whatever means is most expedient. As far as I know there is no hard and fast rules for this on a boat, I would error on the big side.

[Bob Cleek]

There ARE "hard and fast rules" for grounding plates. Check the URL I posted above. And, yes, you can get away with non-marine units, but it's catch as catch can. Do you feel lucky? If you must, and want to save money, check out the motorhome market for similar units, also pricey, but a lot less without a boat on the box. Check out Camping World. You'd be amazed at the amount of "marine" stuff they sell for half the price of the same item at WasteMarine!

[Gerald]

My entire house and shop run on 220 Volts. My planer, MIG welder, 30 HP compressor and larger tools run on 380 volts. I take a shower every day under an on demand 220 volt shower head. These shower heads can be purchased in the smallest of local grocery stores for about 10US$. A common shower head consumes 5,500 watts. I have seen these shower heads wired in some pretty weird ways. However, if you ask around you are probably not going to find one person that has ever heard of anyone being killed taking a shower. I saw a comparable shower head advertised in the United States for 270US$. I would guess that it has every safety device known to man attached to it.
Gerald

[Steve McMahon]

Ahh, the old grounded or floating ground / to bond or not to bond question! First, to clarify: It doesn't matter if your gen-set is 2Kw, 24Kw, or 200Kw, the voltage is what will get you.
A floating ground means that the ground is only grounded to the generator set. A solid ground means that it is also grounded to the rest of the boat. In either case the breakers or fuses will trip just as fast in the event of a short. As long as the appliances / plugs, etc... are wired with cables that have a ground you are somewhat protected. My preferance on a wooden boat is to use a floating ground (isolated ground)with no bonding of metal fittings or ground plates. There are a couple of potential problems / cautions with this: 1) You must use an isolated battery charger. (the cheaper battery chargers have an electrical connection between their AC ground and DC negative and this will cause an electrical couple to your DC system). 2) You MAY get some electrical noise on your electronics and sound systems with the generator running. (this can be minimized or eliminated by paying a bit more and using shielded cable for your AC wiring and gounding only one end of the shielding, preferably at the generator set end) 3) Depending on what standards you are required to meet for your boat, ABS, CCG, Lloyds, Insurance, etc... they may have their own rules. If you have to meet more than one standard, ie: ABS and Lloyds, their rules may contradict eith other! Unfortunatly many of the rules are written for steel and fglass boats and are applied to all.
As others have said, if you have shore power you must use a totally isolating transfer switch (3pole, double throw). If you have a grounded system you must use a 1:1 isolating transformer to protect yourself from stray marina currents. If you have a isolated ground system on your boat this is not required because there is no path to your boats ground.

I hope this helps.