Shore Power and 110v Wiring

[CarinaPDX]

I need to add, the most common AC electrical cause of boat fires is the power inlet connection. Before you do anything else, take a look at the three blades in the inlet connection: if there is corrosion replace them immediately. Also check the mating socket on the cord end for corrosion. If there is corrosion the resistance goes up and it will create a lot of heat, particularly when you are running heaters, etc. This is essential.

[TheScarab]

Originally Posted by CarinaPDX

I need to add, the most common AC electrical cause of boat fires is the power inlet connection. Before you do anything else, take a look at the three blades in the inlet connection: if there is corrosion replace them immediately. Also check the mating socket on the cord end for corrosion. If there is corrosion the resistance goes up and it will create a lot of heat, particularly when you are running heaters, etc. This is essential.

good advice, thanks.

[CarinaPDX]

Perhaps being scared is a good thing. Last summer a boy got shocked trying to board his father's boat here. IIRC his father had to pull him off. I think it was an error in the marina's wiring, but the boat may have had a problem instead/in addition. No one was talking much...

And even if no one is hurt, it is not funny to have to replace a prop due to electrolysis. Or to have a boat sink because the thru-hull failed. These are not just theoretical concepts. In fact, I was in an electrically leaky marina in the UK, using just a transformer and power strip (no local ground connection so not my fault), but the stray currents did corrode my prop. Or at least I think that is what happened - it is hard to tell after the fact. What I do know is that the electrician kept fixing the problem of the RCD (ELCI) for the float tripping by adjusting the trip level higher. Very impressive...

[TheScarab]

did he die?

lol

how about "DON'T GO SAILING...SOMETIMES BOATS SINK"

I understand what you're saying about professional help. I would prefer to pick up the phone, call someone have them come down and fix it all up for me.

Unfortunately that really isn't an option. If it was, I'd do it.

[CarinaPDX]

Start hanging out in the marina and making useful friends

[TheScarab]

Originally Posted by CarinaPDX

Start hanging out in the marina and making useful friends

[sailorchic34]

As others have said, Black is hot, white is neutral and green is ground. But don't assume that is how your boat is wired at the moment.

The short course is Black goes to the breakers, All Whites go to a common strip and return to the shore. All green go to a separate strip and return to the green shore line. The green and white wires should not be interconnected on the boat, that is tied to the same point.

You ALWAYS want the green ground wires going separate out the boat...

The main 30amp breaker should be a double pole (for 120V in the states) with Black (hot) and neutral (white) both connected thru it. This way if the dock power is wonky, (That is wired backwards, which happens now and then) you have a breaker to kill the neutral also. Way safer that way.

On the power outlets the copper screws are hot (black wire) and silver screws are neutral (white wire). Please note that on DC boat wiring the black wire is ground. Don't get that confused with the AC


As others have said get and read a book at the very least and get a Volt ohm meter and a circuit tester thingy to check outlet wiring. Always work on 120V with shore power disconnected, that is the Shore cable disconnected, not just a flipped breaker. Also if there is an inverter hardwired to the 120V, make sure the battery power to it is OFF.

120V power is very unforgiving on a boat. I know of people who burned their boat up with a bad wiring job. Its very easy to do, specially if your boat was wired incorrectly in the past, which I'm thinking yours was.

Wire Size from the 30amp plug to the panel should be 10 gauge at least. Outlets can be served with 14 gauge wire, though 12 gauge would be safer.

You'll really what to look over your boat wiring before making changes. It sounds like it has a few issues... Hiring an electrician would be prudent.

[TheScarab]

Originally Posted by sailorchic34

All Whites go to a common strip and return to the shore. All green go to a separate strip and return to the green shore line. The green and white wires should not be interconnected on the boat, that is tied to the same point

that's kind of what i figured. not sure why the previous owner did it this way.

there should be a 2nd bus for the green, correct?

[sailorchic34]

YES!. A second bus for the ground....

[CarinaPDX]

Sailorchic34 - nice primer.

TheScarab - I would add that if the existing panel does not have a double-pole inlet breaker, it would be best to install a combined double-pole breaker and ELCI. (Blue Sea Systems, among others, carry such a device.) That is, unless you are adding a transformer, in which case the breaker has to be upstream from the transformer leaving the ELCI to do little useful. In that case an ELCI after the transformer is useful. And there is the problem: it is difficult to give advice without knowing what else is there, or is going to be there, and how things are interconnected.

It might make sense to disconnect the inverter as you suggested. OTOH there is no need to do that if you install an iso transformer. Or use a 3 gang switch to switch all three wires between shore and inverter.

I absolutely agree with Sailorchic34: you cannot trust this installation until it has been surveyed by someone who understands marine AC systems. I would add that there are few things that you can change (safely) without knowing how the rest of the system looks. So back to the need to make a drawing showing all of the connections FIRST. If you can do that, you can attach the drawing to a post and we should be able to provide recommendations. Use color pens (virtually with a drawing program).Then you will just have to decide which of the answers are correct and which are BS

[sailorchic34]

Residential panels (in US) are wired with the neutral and ground connected to a common point in the panel. Thats OK for a house. But oh so bad for a boat. Specially when the dock is wired wrong and hot is coming in on the neutral. The neutral and ground at the dock will be connected back at the main load center (panel) serving the dock. But that is the only place it should be.

With neutral and ground tied together and in the US anyway AC ground tied to the DC ground (Which I'm so NOT a fan of BTW), If hot is coming in on the neutral side (reverse polarity) then you might just get electrocuted touching rigging, or what not. Pretty scary things get done, wiring wise on a boats (and docks for that matter).

Keeping the neutral and ground separate means the ground is never hot (well unless there is a fault that is), even if neutral / hot are reversed.

[CarinaPDX]

Sailorchic34 - absolutely right on neutral to ground connectivity, UNLESS there is an isolation transformer. In that case the output of the transformer (line and neutral) are floating, so neutral and ground get connected to the boat ground for reference. Of course you already know that, but I doubt TheScarab does. Just another opportunity to point out that there is a lot more to this than meets the eye.

[TheScarab]

thanks alot sailorchic and carina.

this is exactly the kind of info i was hoping to get. you've been tremendously helpful.

[CharlieJ]

As a guy that does this for a living, I mean this in only the most respectful manner: This Forum is not the venue for you to receive answers to your electrical questions given your demonstrated lack of even basic technical electrical knowledge. You are dealing with issues that can literally kill you or yours and can destroy your boat and others around you.

My suggestion is to find a qualified ABYC Certified Marine Electrician, and have him perform a formal, detailed electrical survey of your vessel including recommended corrective actions. Develop a working relationship with the Electrician and start correcting the defects under the Electrician's periodic guidance. You will learn a lot about your vessel, how to troubleshoot, how AC and DC systems are supposed to work, and a lot of practical electrical skills.

You will then have the lexicon to delve deeper into the subject if you wish and books by Calder, Shermann, Wing and others will have real meaning for you. This course of action won't turn you into a Marine Electrician but it will produce an electrically safe vessel with an Owner who has the basic electrical troubleshooting and installation skills to maintain it safely.

[TheScarab]

Originally Posted by CharlieJ

As a guy that does this for a living, I mean this in only the most respectful manner: This Forum is not the venue for you to receive answers to your electrical questions given your demonstrated lack of even basic technical electrical knowledge. You are dealing with issues that can literally kill you or yours and can destroy your boat and others around you.

My suggestion is to find a qualified ABYC Certified Marine Electrician, and have him perform a formal, detailed electrical survey of your vessel including recommended corrective actions. Develop a working relationship with the Electrician and start correcting the defects under the Electrician's periodic guidance. You will learn a lot about your vessel, how to troubleshoot, how AC and DC systems are supposed to work, and a lot of practical electrical skills.

You will then have the lexicon to delve deeper into the subject if you wish and books by Calder, Shermann, Wing and others will have real meaning for you. This course of action won't turn you into a Marine Electrician but it will produce an electrically safe vessel with an Owner who has the basic electrical troubleshooting and installation skills to maintain it safely.

i looked up your company on the 'net.

tell you what...............

i build custom websites for a living. yours is broken (http://www.jtbmarine.com/powersurvey.html)

i'll fix your website if you fix my boat.

like you said...

let the PROS do what the PROS do