30 amp shore power to...a can of worms

LANCE ON CLOUD NINE · Feb 22, 2016

There are a few "shore power kits" that include everything you need to bring shore power through a hull receptacle. Or you can custom wire it by buying each component. The kits include the inside plugs also. Once you have shore power it is easy to plug in a small smart marine charger. Many of these are designed to power 12v accessories at the same time they charge your battery. I really like the single bank Minn Kota charger that I have on my O'Day 23. Google Minn Kota battery chargers.
Good Luck .

Benny17441 · Feb 22, 2016

Boats with shorepower have two separate electrical systems one 12V DC current and the other 120V AC current. Your boat does not have the 120V AC circuitry so you would need to install the whole system. What you call a converter is probably an adapter to allow you to use a 15 Amp plug into a 30 Amp outlet. I think it would be safer if you used the adapter at the shorepower pedestal and ran a 10 or 12 gauge extension cord into the boat rather than the 30 Amp shorepower cable. Don't look at RV electrical components as their needs vary from marine applications. Most RVs do use converters to supply 12V power for house needs and only use battery power when boon docking while boats rely mostly on battery power to supply 12V needs. A dedicated battery charger is usually hardwired into the AC electrical system to keep the batteries charged. If you do not ever intend to leave the dock I guess it could be considered as an RV and you could use a converter. A 120V electrical shock could be fatal so a 120V electrical system should be installed by a licensed electrician with ample experience in marine installations. The common wires and connectors used in home construction are not adequate for use in boats. Of the top of my head you would need a 30A exterior plug fused and wired into an electrical panel with breaker switches for each individual circuit, outlets, battery charger, refrigerator, etc. If you are running outlets to both sides of the boat you might need two circuits to be able to handle perhaps 15A in each circuit rather than just 15A for all. You may lead each outlet circuit with GFCI outlets. If you can do all you need with just a couple of outlets you might be able to do with a small panel and a less costly installation but it needs to be safe. Do your homework.

Maine Sail · Feb 23, 2016

A shore power system needs to be done correctly and wired correctly or it can be deadly.

This would be a bare minimum safe AC system:

50' 30A Smart Plug Shore Power Cord
30A Smart Plug Shore Power Inlet
10GA Triplex AC Marine Wire (max 10' before another 30A breaker is required)
30A Fail Safe Galvanic Isolator
AC Panel - Reverse polarity, 30A double pole main , branch breaker slots Blue Sea 8099 or Paneltronics 9972313B
14GA AC Triplex Marine Wire
15A GFCI Outlets (hospital grade hold up best)
MARINE BATTERY CHARGER - must meet marine UL standards DO NOT USE AN AUTOMOTIVE CHARGER!

IMPORTANT: Any equipment such as inverters, inverter/chargers or battery chargers, that are used on a boat, should meet Marine UL requirements or they can create dangerous situations when used on a boat. Marine inverters and marine chargers are built to an entirely different level.

AC White/Neutral is not bonded on-board the vessel only back on shore (unless you have an inverter, generator or isolation transformer)
AC Green/Protective Earth is bonded to the ships DC system ground point

If the wire between the shore inlet and the AC panel main breaker is more than 10 wire feet then an additional 30A double pole breaker is required. In a marine system the main breaker MUST interrupt both AC Black/Hot and AC White/Neutral. If the vessel does not have a reverse polarity indicating system then branch breakers must also be double pole.

If you don't understand these points it would be wise to consult a professional...

This is the proper wiring diagram for the most basic of AC systems. I would not however suggest that a galvanic isolator is "optional" unless your dock is behind your own house with no other boats on it. The GI should be a "fail safe" type..

Maine Sail · Feb 23, 2016

westfam said:
BE, I'm in touch with dyersonline.com to see if they advise against use in marine applications. If not, then I'll need a marine equivalent, all-in-one converter/inverter/charger. Every aspect of what you've described is what my engineer intends to install. 30amp receptacle feeding into a main breaker panel/charger/brain. It will charge /tend my batteries, distributw power to all of the stock 12v accessories through out the boat, aS well as the newly installed 120v dc outlets we're adding throughout the boat. Every gfci will have a dedicated 15 amp circuit.

An inverter is not what you want for shore power. RV power centers are NOT marine... You will have a separate AC system and DC system. If you want an inverter or inverter / charger then you will also need the battery capacity to drive it when inverting. The most simple system is what I described above plus a good quality marine battery charger.

Some of the Progressive Dynamics chargers meet Marine UL but they would be very, very low on my preferred list of battery chargers as they lack a lot of good features like custom program-ability and temp compensation. Their charge voltages are also not healthy for batteries and without the ability to custom program it is a LOT of money for a charger that is giving you very little in terms of actual battery charging performance..

Installing A Marine Battery Charger (LINK)

Gunni · Feb 23, 2016

Wisdom? You hire a marine electrical specialist (ABYC cert) with at least half the expertise of Maine Sail, and hand him your requirements. He/she then scopes a marine-suitable install with options. You review those options and decide whether that AC system is worth the second shore power leg, and how much 12 VDC storage you will need to make your refrigerator work. Boat electrical systems are complex and require careful design. Do it right and you add value to your boat. Do it wrong and your boat is a dangerous uninsurable mess that no one wants. A surveyor will disclose all and your boat will be greatly devalued.

centerline · Feb 23, 2016

what you are doing now to bring AC into the boat seems to be a PITA for you... it could also a bit unsafe, but much less so than an IMPROPERLY installed "onboard" AC system.
the components needed to do it right is not expensive considering the longevity and convenience of it after its completed.... and you should consider the fact that a properly installed AC circuit does not devalue your boat, it is safe for you to use and also is safe for other boats in the marina next to you.

you can google "improperly installed ac on boats" and see what comes up. you will get some enlightening information about the issues with AC power installed on boats.

and unless the surge protector you are using now has a circuit breaker built into it for safety, it does you no good for running a coffee maker, heater, battery charger, lights, ect.... all these devices can usually take a spike without any problems at all.
it could help if you have your computer plugged in, but even then most laptops with a converter in the power cord are already have some protection, except in the event of a lightning strike.

if you are going to continue with the extension cord into the boat for awhile (as I have seen so many people do), a good dependable circuit breaker at the boat end of the cord (in addition to the one already installed at the power post) is mandatory for the safety of the boat when you are away from it and a component is plugged into the cord, and for the safety of you and the boat when you are aboard....

Ken Cross · Feb 23, 2016

A couple more things: Don't use household parts such as metal electrical boxes, wire nuts, and solid conductor wire. Get rid of that automotive style battery charger unless you are there inside all the time it is operating. As they said ABYC standards are a must. My last boat had been wired like a house and naturally I ripped it all out immediately. There were numerous things that could have resulted in fire.
Ken

kloudie1 · Feb 23, 2016

I know it is tempting to try to save dollars on the shore power system, but listen to what Maine says.. Here is another article http://www.boatus.com/boattech/casey/safe-shorepower.asp
and: http://www.sailmagazine.com/diy/wiring-your-boat-for-shore-power/

Johnb · Feb 23, 2016

All the arguments above should be enough alone to convince you to do it right but you can also add
If you want to be in a marina
You have to have insurance
To get insurance you may need to pass a survey
To pass a survey you must have power installed correctly

dlochner · Feb 23, 2016

westfam said:
Thank you all for the sound advice. I will not make any decisions without consulting a pro marine person as you've suggested. I'll let you all know how it is coming along.

The Pro you want is an ABYC certified marine electrician. There are some books out there that will help you understand the electrical system. Check out:

Boatowners Mechanical and Electrical Manual 4/E
Boatowner's Illustrated Electrical Handbook

Educate yourself so you will know if the job is being done correctly and so you can trouble shoot it fails.

Ken Cross · Feb 23, 2016

It certainly can be done by the owner. It would just require sticking to the same practices the pro uses.
If you have no electrical background, it would however require a steep learning curve.
Ken

dziedzicmj · Feb 23, 2016

I hate to say it like that, but in many cases when we warn others that something (like an electrical installation) is potentially unsafe, many read it as " it might be potentially unsafe, but I can easily do it myself anyway and nothing would ever happen to me", or "it is as unsafe as drinking hot coffee at McDonald's" (hence the warning label on the cup). In case of electrical wiring on a boat, if you do it incorrectly, you risk electrocuting yourself (kind of, your own problem), affecting your boat's metal parts' corrosion (again, kind of, your own problem), but also affecting others - stray currents in the water, galvanic corrosion on other boats etc. Those are problems that affect everyone around you and this is why everyone calls for proper installation.

Stu Jackson · Feb 23, 2016

dz is right.

Just remember, none of us were born electricians.

We all spent time and energy learning how to do it right.

How? We read the books suggested. We read Maine Sail's website. We read material on good websites by vendors of electrical equipment, like Marinco and Blue Sea.

We drew wiring diagrams BEFORE we ever touched a wire.

We drew wiring diagrams before, during and after we did ANY electrical work.

We were careful. We listened. We never cut corners. If we didn't know WHY something was REQUIRED, we found out, first.

We ended up with successful and working and SAFE systems.

Good luck.

Benny17441 · Feb 23, 2016

I think you may putting the cart before the horses. The boat is new to you and you have not even taken it out sailing yet. I'm sure you can sustain the use of an adapter and an extension cord for a while longer until you figure out how you are going to be using the boat and what your real needs are. Don't wait for your first purchase as you need to replace that automobile unit you are using with a marine battery charger. You can find a multi stage, 10A charger with leads for two batteries and with a 15A plug at around $125. I used to have an h27 and it came from factory with a very simple 120V system consisting of the shorepower plug connector, a single pole breaker and three sets of outlets. The thing is that I was able to run refrigeration, A/C window unit, a microwave oven, an inboard battery charger, a heater, fans and a TV/DVD player from basically just two of those outlets as the third was inside the cabinet by the wash sink near the head. I had to manage the usage of the appliances as not to exceed the available power but that is something you may have to do any ways. Manufacturing and safety standards have changed requiring some updated components but a basic electrical system can be installed at a moderate cost.

Stu Jackson · Feb 23, 2016

As you spend more time here, you'll learn that benny's input is always very astute and valuable.

You might also be interested in these:

Electrical Systems 101 http://c34.org/bbs/index.php/topic,5977.0.html

BayMan · May 16, 2016

Maine Sail said:
A shore power system needs to be done correctly and wired correctly or it can be deadly.

This would be a bare minimum safe AC system:

50' 30A Smart Plug Shore Power Cord
30A Smart Plug Shore Power Inlet
10GA Triplex AC Marine Wire (max 10' before another 30A breaker is required)
30A Fail Safe Galvanic Isolator
AC Panel - Reverse polarity, 30A double pole main , branch breaker slots Blue Sea 8099 or Paneltronics 9972313B
14GA AC Triplex Marine Wire
15A GFCI Outlets (hospital grade hold up best)
MARINE BATTERY CHARGER - must meet marine UL standards DO NOT USE AN AUTOMOTIVE CHARGER!

IMPORTANT: Any equipment such as inverters, inverter/chargers or battery chargers, that are used on a boat, should meet Marine UL requirements or they can create dangerous situations when used on a boat. Marine inverters and marine chargers are built to an entirely different level.

[End Quote]

I now have an antique Xantrex inverter/charger that is giving me issues. I have to decide to fix it or replace it. Maine, you are clearly not in favor of inverters on a boat. Does your opinion go as far as recommending that people like me change to a system more like you describe in your post?