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fireplace77
21 Posts |
 Posted - 02/22/2009 : 2:26:45 PM
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I not wanting to change my main two wires in my panel box but that is what the marina is telling my i need to do , i' guess i have one ? why did it work great on the trailer in my yard ,but the power is not working at the dock side marina? i think it is polarity sensor or may a ground sensor?? buzzing what mite it be doing it on my carver it is a 1976 carver 2896 ?
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woodboat
Canada
131 Posts |
Posted - 02/25/2009 : 2:34:21 PM
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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.
http://www.boatus.com/boattech/casey/36.htm
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Edited by - woodboat on 02/25/2009 3:02:04 PM |
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Rockmeister
USA
307 Posts |
 Posted - 03/03/2009 : 3:29:06 PM
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What Woodboat posted is exactly correct!
To simplify it to your situation:
Usually the buzzer is connected between Neutral and Ground.
Under NORMAL circumstances, there will be little to no voltage difference between the Ground & Neutral so the buzzer is silent.
If the Neutral and Hot are reversed anywhere in the circuit, the buzzer will sound.
Also if the ground is NOT grounded and is actually possibly Hot, the buzzer may sound.
If you have a bad connection in the Neutral AND/OR the Ground, the buzzer will sound.
(In this case, the more current you draw, the louder the buzzer. Makes for an easy test.)
What you need to do is locate exactly WHAT & WHERE the issue is.
You will need a meter or test light for this. (meter is better)
Ground test: (All tests performed with boat plugged in and buzzer buzzing)
Connect the meter between ground terminal on an outlet and the water.
Meter should read low voltage (10v or less, ideally Zero.)
If it is above 10v, you need to isolate WHERE the bad ground connection is.
Repeat test at shore power outlet, between shore power outlet & water (or the ground you are standing on).
If it is above 10v between the electrical ground and the earth ground at the shore power box, the marina has a serious issue.
(You can also have an issue yourself in addition to a possible marina power issue.)
Neutral test is almost the same as the ground test, except also check between the neutral terminal and the ground terminal, should be less than 10v.
Am willing to bet you get 120v(nominal) between Neutral and Ground (Hot & Neutral are reversed.)
Do some tests and let us know what you find.
While doing the tests, be VERY careful!
Something is wrong and it very well may be very dangerous! 
IE, as you are doing these tests, do it with dry hands/feet etc and do not touch anything metal!
I will help as much as I can, can also help by phone if needed.
Rock 
79 28' Mariner twin inboard V-drive.
SW Lake Erie: Maumee Bay & The Islands |
Edited by - Rockmeister on 03/03/2009 3:34:34 PM |
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woodboat
Canada
131 Posts |
Posted - 03/05/2009 : 1:57:32 PM
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| Hey rockmeister, wanna help me wire my boat? (120vac) ...needs total from shorepower inlet on, and I am a bit scared to do this on my own... also have to get all the parts - panel, main, and three circuits should do it... need the wire too... got a good source for these items? tx |
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Rockmeister
USA
307 Posts |
Posted - 03/06/2009 : 10:00:43 PM
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Heyya Steve!
Would actually love to help ya wire your boat! Like those kinda projects!
Problem is... You are Waaaaaaay over there! *points* lol
Can help ya with inexpensive parts and info though.
https://www.surplusunlimited.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=0400-30
Like this one:
https://www.surplusunlimited.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=2022&Category_Code=0400-30
These guys are great, fast shipping also.
If they have it, is usually a pretty good deal.
(Most of their stuff is overstock/surplus.)
(Think we have Dale to thank for bring this particular site to my attention.)
Believe they have tinned/finely stranded marine wire also.
This one has the double pole breaker & 1 breaker position.
(You can drill more holes for more breakers.)
http://www.go2marine.com/product.do?no=21410F (Surplus)
FlounderPounder also has surplus.
http://www.fpmarine.com/
Have seen a panel much less than that yet, will try to remember where and let you know.
(It was surplus and about $100 with all minimum requirements.)
3 Circuits should easily do ya, even with air taking one of them.
I have more but mainly use the 3; 1 air conditioning, 1 half the outlets, 1 half the other outlets.
Would suggest a 4th circuit maybe seperate even from your mains (still circuit breaker protected as required), ONLY to run your chargers, this one should NOT have easy access to most users, and should probably NOT have gfi protection, it is ONLY used for the chargers. (Mine is under the dinette seat.)
That way if lots of things go wrong at once, your bilge pumps will still work! (IE, you don't sink.)
Things to look for: (Would consider these minimum requirements.)
A polarity indicator, sound and/or light.
Would STRONGLY suggest having a double pole main breaker. (MUCH safer.) 30A
The branch breakers can simply be single pole breakers.
(Can get the marine AC/DC breakers on ebay for $20 or less each shipped.)
Branch breakers are easily added later with drilling a few holes.
Would definitely get a panel with a neutral and a ground buss (they are seperate entities)installed already, this makes life MUCH simpler and safer for you.
Have AC meters (Volts & Amps) on mine and love them, but not absolutely required.
Hope this helps!
Rock 
79 28' Mariner twin inboard V-drive.
SW Lake Erie: Maumee Bay & The Islands |
Edited by - Rockmeister on 03/06/2009 11:13:13 PM |
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woodboat
Canada
131 Posts |
Posted - 03/09/2009 : 11:24:37 AM
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Hi Rock, yes, way more than a day-trip ... guess I'll just have to wing it, like the rest of the boat lol
Thanks for the various links... some items quite similar to what I have dug up, but yours a bit cheaper. Would really like to find some source on the Canadian side... the cross border shipping is ok, but the exchange is killing me these days as we sit around 30%.
I agree with the 3 circuits... and the double pole main... I do not employ A/C in the North, but heat is required at times early and late season while at the dock...
For now I will only install an AC panel... though there is no real DC panel, just a row of fuses at the lower helm.
Internet is amazing, though my connection here is not overly reliable... here I am in the desert in California, sourcing parts in Canada from coast to coast - to rebuild the electrical on my boat in North Ontario.
Thanks for your input ~ Steve |
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anyone know what Ishould do on my boat hook up?
