Shore Power Installation - Opinions Please.

[markh1f]

Thanks for all who chimed in on either side of the original question, I appreciate all the input and support. The system was supposed to be a basic system that I negotiated a $395 price as part of the overall deal to buy the boat. I was not expecting the dealer to make much or anything on this option, just to do it to get the sale of the boat. I don't believe it is safe as is and have stopped using it until I re-work it to secure all the loose wires and to replace the breaker box with a panel that has a 30 amp breaker and a reverse polarity indicator.
On the neutral breaker I have been doing some research and the main comming into the boat should be on a double pole double throw breaker that opens both the hot and the neutral circuits so in case the dock is wired with reverse polarity there will be no live wire when the breaker is open. Otherwise you could have a situation where the breaker is open and you go to do some wiring and get a nasty surprise. I am no electrician but that is what I have been reading.

Mark

[Divecoz]

Now I have a question? What causes that double pole single throw breaker to "fault" purely from the existence of reversed polarity?

In the case of the tell tail light , it only gives you " I am lead to believe" a visual warning . The system still operates.
But hey so you know and while we are having this discussion.....
Breakers versus fuses.......my chance for over kill... During my supervision of one of the Control stations for a Nuclear Power House . I was asked by one of the fellows . Why are we installing old technology ? He was referring to glass fuses in the control panel. Simple answer , at least before the advent of Made In China....... Fuses are far more fail safe than breakers...By and large Non Marine Industry standard breakers are not sealed and will absorb atmospheric moisture and then corrode. Corrosion can either slow down the trip or eliminate it entirely. There is a saying around the industry that would never pass the censors here ....but least it to say . Not all breakers are made equal. Lets just say that the rule of thumb is you get what you pay for ...that cleaned that up hahahaha.
BTW where is the worst place to install a breaker panel? Yep most of you got it ..... in your basement, bathroom or yes as I have seen in a few places Outside !
BTW $395.00
with less than $100 spent on materials and less than $100 hahahahaha 2 hours in labor .... he made No Less Than $195 or 49.3% profit....

[Hardcrab]

Dive,
Nothing will. My point for Highlander.
But, the double pole breaker just might make total sense short of pulling the dock plug entirely for miss wired dock power.
Any short or overload will open the hot and neutral leg (miss wired as the hot leg), so nothing can be hot on the boat causing the saftey problems noted above. Refer to your own argument.
Complete isolation, a good thing.

The "miss wired indicator" can be built from Rat Shack stuff for $2.79, as I recall.
The neon bulbs I used will last a long time.

On edit:
On deeper thought, I have learned something new today.
Yes, a double pole breaker as the main in your boat should be used in the event of a miswired dock plug and a "fault indicator" is not used, IMHO.
You will not risk electrocution if a short or overload onboard will trip both legs at the same time.
Highlanders boat is safe, if his breakers are double pole configured.

[SkiDeep2001]

Here's a simple cheap solution to check for miswired or ungrounded shore power. Works for RV parks, docks, home, etc..... Available at most hardware, RV supply or Harbor Freight. http://www.harborfreight.com/cpi/ctaf/D ... mber=32907

[Divecoz]

.
Highlanders boat is safe, if his breakers are double pole configured.

Hahahahaha NO but he knows there is a problem and he can disconnect the boat from the power source rather easily from the inside . I am laughing because in my mind ....I am wording this so well. But in this thread I am soooooo failing the test! Not unusual for me BTW . I will ask as well, if Mark needed to do the same thing ... toss the disconnect ? How much more difficult would it be to actuate his system than Highlanders?

I was just thinking about a time we were having difficulties with an arrant voltage source...We could not find the source . I look over to see Darren our 1st year apprentice and he has put on a pair of rubber boots... Darren?? What the heck??
He smiles and says I am insulated now...Darren your still kneeling on the concrete and your leaning against the frame #$%^&*

[violaman]

Safe Shorepower
by Don Casey

However you bring shorepower aboard your boat, if you do it without the appropriate safeguards, you place yourself, your crew, and your guests at a terrible--and foolish--risk.

Three-Conductor System
AC circuits use three wires, and it is essential to your safety to understand the function of each. Because the direction of current flow in an AC circuit is reversing 120 times per second (60 positive-to-negative-and-back-to-positive cycles), it is counterintuitive to refer to one side of an AC circuit as positive and the other as negative. Instead, we call one side hot, the other side neutral. By code the hot wire in an AC circuit is black, red, or blue; the neutral wire is always white. Since the neutral side is connected to ground, it is the hot side of the circuit that is the most dangerous. However, you should always treat both sides with equal respect because a wire reversal to the outlet will make the neutral side hot.

The third wire is called the grounding wire and it connects all metal component, junction, and appliance housings to ground. Since neutral also runs to ground, you might wonder why we need a second grounding wire. It is there to keep you alive. If, for example, a wire inside an appliance comes in contact with the case, the case becomes "hot." No fuse blows because there is no circuit and thus no current flow--not until you touch the case. Then your body completes the path to ground and you get a nasty shock.

The grounding wire changes all that. A short to the case instantly becomes a short to ground, probably opening the breaker in the circuit. Even if the short is insufficient to kick the breaker, or if it occurs while you are holding the appliance, the grounding wire still protects you by providing a lower-resistance path to ground than your body offers. Anything that degrades or opens the grounding circuit, such as a broken connection, a corroded or missing ground prong, or an improperly wired outlet leaves you dangerously vulnerable. Ashore the grounding wire is often bare, but in boat wiring it should be insulated and green. We will come back to this all-important green wire.

Inlet Fitting and Dock Cord
A safe shorepower system begins with a weather-tight inlet fitting. If the shorepower inlet on your boat isn't weather-proof--with and without the cord attached--you need a different fitting. The 30-amp locking receptacle has become the norm at most U.S. and Caribbean marinas, so equipping your boat with a 30-amp inlet minimizes compatibility problems.

Make sure the fitting is in a location that does not put it at risk for submersion or mechanical damage, and that the backside is well ventilated. The wire distance from the inlet to the main AC circuit breaker should never exceed 10 feet.

An extension cord from a builder's supply, even one labeled "Heavy Duty," is not an appropriate shorepower cord. To shrug off the exposure, submersion, abrasion, and strain of marine use, the cable should carry a hard-service rating--SO, ST, or STO. There must be no possibility of the cable pulling free of the plugs (dock cords sometimes become dock lines) or of the plugs pulling out of the receptacles. For 30-amp service, the conductors must be #10 AWG or larger.

Circuit Breakers
Factory shorepower in older boats too often omitted a circuit breaker. The thinking was that a boat was just another "appliance" plugged into the marina circuit, which was already-protected. But faulty marina wiring is too common to entrust your safety to an unknown breaker behind a dock office a quarter of a mile away. A safe AC system requires an onboard dual-pole breaker.

The breaker's rating must not exceed the service; i.e., a 30-amp inlet limits the main breaker to 30-amp. However, if the circuit directly supplies outlets in the cabin, the size of the breaker is limited to the outlet ratings--either 15 or 20 amps.

A single-circuit offers the benefit of simplicity, but if you need multiple AC circuits, breaker panels are available with a main breaker and two or more branch breakers. Despite being commonplace, it is not a good practice to combine AC and DC in the same breaker panel.

Polarity
Reversed polarity leaves your AC circuits unprotected if you have a single-pole main breaker since the breaker is now on the neutral side. Even with double-pole breakers, reversed polarity puts ON-OFF switches on the wrong side of the circuit, leaving OFF appliances fully energized. Be sure your AC panel is equipped with a polarity tester.

Where branch breakers are single pole, be sure they are on the "hot" side of the circuit.

Wire
Resist any temptation to use house wire (Romex) for the AC circuits on your boat. Common house wire is solid copper, fine for a quiescent life inside a wall but unsuitable for the marine environment. Boat wiring requires the flexibility of stranded wire, and it should be tinned for corrosion resistance.

Wire size for AC circuits is generally less a factor of voltage drop than of amperage capacity, but starting currents, particularly for compressors, can momentarily increase the current draw up to 5 times nominal. If the wire is too small, this momentary surge can actually cause supply voltage to drop below the level required to start the compressor. As a practical matter, 15 and 20 amp circuits should be wired with 12-gauge wire. The (unprotected) wire between the inlet fitting and the main breaker should be 10-gauge for a 30-amp inlet and 6-gauge if the service is 50-amp.

Grounding
The green "grounding" wire in AC circuits provides a low resistance path to ground should any of the various metal cases enclosing your AC system become energized. But what if the leak is into the DC wiring, caused, for example, by crossed wires or a short in a battery charger, inverter, or other dual-voltage appliance? AC leaking into the DC system will seek ground, meaning it will automatically travel through the wiring to the ground connection on the engine and down the prop shaft to the water. This is essentially the same as dropping a hot wire into the water. In fresh water, this poses a real risk of electrocution for anyone in the water nearby. Electrocution is less likely in saltwater, but the current field can be enough to paralyze muscles and cause a swimmer to drown.

Connecting the green wire to the ground terminal on the engine offers AC leakage into the DC system a lower-resistance path to ground--through the grounding wire. This eliminates the risk to swimmers as long as the grounding wire connection to ground is sound. However, if corrosion on the ground prong of your dock cord or some other fault breaks the ground connection, all ground-fault current, not just AC to DC leakage, will flow into the water. It is essential to test the ground connection at the dock and to maintain cords and plugs in good condition.

In your breaker box at home the neutral wires and grounding wires all connect to the same terminal strip (or bus bar), but on a boat the AC grounding wire is connected to the DC ground. Also connecting the neutral wire to it makes underwater hardware a current-carrying path to ground, potentially lethal for anyone in the water nearby. On a boat the neutral (white) conductor and the grounding (green) conductor MUST NEVER BE DIRECTLY CONNECTED.

Outlets
Outlets are all polarized, and the Lone Ranger's white horse, Silver, can provide the association necessary to remember which wire connects to which terminal. White goes to silver. So the black wire connects to the opposite terminal, usually brass, but sometimes dark. The green terminal is for the green grounding wire.

Electricians ashore simply tighten terminal screws onto a loop of wire or insert the stripped end into a spring clamp. Neither method is appropriate on a boat. Use a proper crimp terminal or install commercial-grade outlets with screw-tightened clamps in place of the more typical screw terminals. These may be used with stranded wire.

Ground Fault Interrupt
Regular circuit breakers are essentially fire-protection devices and offer no protection against electrical shock. A ground-fault circuit interrupter (GFCI), on the other hand, provides a high degree of shock protection. If you accidentally touch an energized wire or component and you are grounded, the GFCI disconnects the circuit in about 1/40 of a second, too little time for the current to build to a dangerous level.

In recognition of the increased risk of shock in damp environments, many municipal building codes mandate GFCIs in bathrooms and, increasingly, kitchens. Boats are damp environments, and every outlet on a boat should be protected by a GFCI.

GFCIs are inexpensive and easy to install. Simply replace the first outlet on a circuit (counting from the breaker) with a GFCI fixture, and all the outlets on that circuit will be protected. Make sure the terminals marked LINE are connected to the wires leading back to the breaker and those marked LOAD feed the remainder of the circuit. After you install a GFCI fixture, always test it.

Safety
The safest course is to leave AC system repairs to a qualified marine electrician, but if you opt to do the work yourself, never, ever work on an AC circuit hot. Disconnect the cord--and take it off the dock, lest some Good Samaritan send you to the next life. Also disconnect the inverter. Then religiously check all wires with a voltage tester. This is the electrician's version of "measure twice, cut once." Be absolutely certain that there is no voltage between any two wires or any wire and ground.

When it comes to AC power, what you don't know definitely can hurt you.

AC aboard raises a number of additional considerations not covered here. Sailors and powerboaters alike will find a more complete treatment in Sailboat Electrics Simplified by Don Casey.

[Divecoz]

Here's a simple cheap solution to check for miswired or ungrounded shore power. Works for RV parks, docks, home, etc..... Available at most hardware, RV supply or Harbor Freight. http://www.harborfreight.com/cpi/ctaf/D ... mber=32907

Thats the one and for $5 it even checks the GFI function.... hard to beat....
Good source violaman!!!! I own several books by Mr Don Casey. Marine Electrical is only at best, similar to General Electrical Installations.

[SkiDeep2001]

violaman, where you been the last few days, we could have used your considerable knowledge so we all weren't going round and round trying to explain why this was a bad install, you nailed it All we knew was it looked like a duck, quacked like a duck but we just couldn't articulate it well. OOPS, I guess I should change the above to where have you been with Don Casey's considerable knowledge, gotta give credit where it's due

[J.Teixeira]

Suggestion to Heath

It would be very interesting and enriching to this web site if this kind of "High Quality posts" would be "collected" into a technical articles library...

On the Resources Menu

Also it would be nice to have in the resources the Mac Google Map

???

[Ivan Awfulitch]

I think it's a great idea. I have a Blue Seas panel similar to this one, except mine has an analog meter. If you can find one, they're about $200 and easy to install. All of these have a reverse polarity indicator so you know when you have a "hot" neutral. Simply add GFI outlets to the circuits and you've got a nice safe installation.

http://www.skipper-dan.com/products/20829b.htm

The breaker does break both the hot and neutral, so that if you have a marina with a reverse polarity situation you safely disconnect with the main breaker before working on any electrical.

[Divecoz]

Want to amp up this discussion ? Lets read what Mr Casey has to say above , about Grounding. The grounding of AC and DC Panels in unison....How a Ground is effected from AC rectifier to Power Pedestal and a 12 Volt ground source through the engine and into the water lets then lets toss in a generator with an automatic transfer switch.... the more stuff you add, just like with most other systems, we all work with or on everyday... from Computers to recipes for Fettucini, the more involved things get the greater chance of error. When dealing with Electricity error can be spelled Injury or Death

[violaman]

Hi Ski,
Sorry for late intrusion. As i was reading this thread, I was getting more and more confused. So,.. When I cannot find answers to life's persisted questions, I open Don Casey's Boat Bible.
There are three commandments: Breakers for both terminals, Marine grade equipment, use appropriate gauge wires. And, Do Not Use common sense,... Use reliable knowledge.
Ilya

[Divecoz]

Hummmmmmm I have Don Casey’s Complete Illustrated Sailboat Maintenance Manual 896 pages and I guess I need to look ...I am surprised Don Casey suggest ...Breakers for both terminals I leave tonight for a long weekend but will check when I get back.

[Highlander]

Yes it is double poled as you can see in tis pic

http://i235.photobucket.com/albums/ee20 ... 010074.jpg

J

[Hamin' X]

I am chagrined to say after looking it up, that double breakers are an ABYC standard, but only if they are a combined breaker like Highlander's. Separate breakers would lead to the dangers discussed above. He also, understands the importance of a combined AC and DC ground system and the necessity to keep the AC neutral and ground separate on the boat.

~Rich