Shore Power and 110v Wiring

[Tellie]

Originally Posted by TheScarab

lol...

anyone else want to tell me to go learn about wiring before i start?

kind of thought i'd get some first hand info here, maybe LEARN a bit.

instead so far it's just folks telling me that i shouldn't do it because i don't know what i'm doing...

NO ****................

what good is a community forum for sharing info and ideas (LEARNING) when people's only input seems to be YOU NEED TO LEARN?

OK fine we were wrong, so you do know a ton about electrical work and you were just yanking our chain when you lied. So go get some #14 AWG romex from HD, some electrical tape and a handful of wire nuts and have at it.

[btrayfors]

What no one has mentioned thus far -- maybe delicately skipped over -- is that fooling with 120 volt AC systems on your boat with the level of knowledge your posts evidence thus far....

CAN KILL YOU

Easily and completely.

For god's sake, man, get help from a local electrician.

Bill

[TheScarab]

Originally Posted by CarinaPDX

I'm a big fan of DIY for cruising, but it looks like you are WAY over your head if you don't understand Line-Neutral-Ground differences, and know the color codes. This is not meant to offend you, but alert you that this is something that needs knowledgeable eyes. One could fill volumes about the grounding issues alone; the green wire may have been intentionally disconnected for good reason, but it also could be a safety hazard. As noted above, a galvanic isolator is now considered minimum equipment by the ABYC folks, and there is a very good chance you don't have one if the boat is old. Personally I prefer using an isolation transformer that can also be used to step down 220v (or step up 110v if the boat uses 220v). This is probably meaningless to you, so just trust that someone needs to put together a circuit diagram of your AC power system, and recommend changes/upgrades. If you don't have someone in the marina who is knowledgeable and willing, then hire a professional marine electrician - it will be worth every penny. This is simply not an area that can tolerate errors - it is critical to the safety of those aboard, and to the boat itself. Of course people here will try to help, but nothing can replace those knowing eyes seeing first hand the situation. Good luck...

understood...

Originally Posted by CarinaPDX

the green wire may have been intentionally disconnected for good reason.

this is one of the things i'm trying to determine.

personally, i'm not aware of a reason to leave a ground disconnected. however, before i go in and start wiring things to how i 'think' they should be, i wanted to check with others who might know a few things i don't know.

it's also helpful for me to get plain explanations regarding the prinicples behind electrical wiring. I know enough to look at it and say 'this should be this way and that should be that way' but I want to fully understand exactly what's going on with the electricity.

the posts about the ELCI boxes etc are very helpful as the boat is older (1983) and yeah, i'm not interested in setting it on fire just yet.

i do know a bit more than i let on to begin with. i just wanted to get the most rudimentary of information along with the more advanced theory - sort of as a benchmark or comparison to my thinking.

[TheScarab]

Originally Posted by btrayfors

What no one has mentioned thus far -- maybe delicately skipped over -- is that fooling with 120 volt AC systems on your boat with the level of knowledge your posts evidence thus far....

CAN KILL YOU

Easily and completely.

For god's sake, man, get help from a local electrician.

Bill

lol...no.

[CarinaPDX]

I see that there have been quite a few post while I was writing my post, so let me add:

I really appreciate your desire to do this yourself. If I were in your marina I would gladly visit your boat, diagram the AC system, and recommend what you need to do to bring her up to spec. In fact, I just did that with a boat here, who had failed that part of the survey, and he now has new wiring, an ELCI and an iso transformer, as well as new power inlet/connection. My concern is that in this area, a little knowledge is a dangerous thing - potentially really dangerous. Not understanding all of the implications of a circuit design can lead to bad choices. And there are many possible configurations, all of which function, but only some of them are safe.

Barring a (local) friend with knowledge, then it really is worth paying for help - no matter how boat-broke you are. If you want to learn you can ask him. And here. But designing/repairing an AC system is not the place to start learning about electricity.

My 2¢, offered in the spirit of helping you get out cruising (safely).

[bobofthenorth]

Originally Posted by TheScarab

@bobofthenorth

just curious...

do YOU know what the purpose of a neutral wire is in a 120v wiring system?

As a matter of fact yes I do. And the fact that you don't means that you are WAY over your head. Listen or don't listen to the advice you're getting. As long as you're not moored next to me it won't be my boat that you burn down.

And you're not moored next to me.

[TheScarab]

man....

i just bought the boat. i'm moored next to someone right now. i'm on the boat. i have shore power coming into an electrical panel and the ground from the incoming current is dangling. there are other disconnected wires to the electrical panel. i have no money for an electrician right now.

tell me again to not do anything about it.

[CarinaPDX]

As for why the green wire was disconnected, consider this: The boat was probably not built with the inverter. Wiring the inverter requires connection to the ship's ground (by both the safety ground and the current-carrying neutral wire). Unless the switch that switched between shore power and the inverter also switched the safety ground as well as line + neutral, that would result in connecting the shore safety ground to your underwater ground point - possibly your propeller and shaft. Should there be a difference in potential you could end up with an eroded prop (or other underwater metal corrosion). The easy fix is to break the safety ground connection; depending on where this is done it could also remove the safety aspect of this ground. This is why it is now standard to use galvanic isolators or isolator transformers to eliminate this problem. Needless to say, there is a lot more to the topic of grounds, safety, galvanic and stray current corrosion. Hence the recommendation to seek a professional.

[mitiempo]

Originally Posted by TheScarab

personally, i'm not aware of a reason to leave a ground disconnected. however, before i go in and start wiring things to how i 'think' they should be, i wanted to check with others who might know a few things i don't know.

it's also helpful for me to get plain explanations regarding the prinicples behind electrical wiring. I know enough to look at it and say 'this should be this way and that should be that way' but I want to fully understand exactly what's going on with the electricity.


i do know a bit more than i let on to begin with. i just wanted to get the most rudimentary of information along with the more advanced theory - sort of as a benchmark or comparison to my thinking.

If you do not "fully understand exactly what is going on with the electricity" how could you ever "look at it and say 'this should be this way and that should be that way'?

I agree with Bill - 120 volts can easily kill or start a fire. Best to hire a qualified marine electrician to go over the wiring on your boat.

[Tellie]

Just for fun, one of my favorites...

FunnyFuseFaves: Electric Shock Prank! - YouTube

[TheScarab]

Originally Posted by CarinaPDX

As for why the green wire was disconnected, consider this: The boat was probably not built with the inverter. Wiring the inverter requires connection to the ship's ground (by both the safety ground and the current-carrying neutral wire). Unless the switch that switched between shore power and the inverter also switched the safety ground as well as line + neutral, that would result in connecting the shore safety ground to your underwater ground point - possibly your propeller and shaft. Should there be a difference in potential you could end up with an eroded prop (or other underwater metal corrosion). The easy fix is to break the safety ground connection; depending on where this is done it could also remove the safety aspect of this ground. This is why it is now standard to use galvanic isolators or isolator transformers to eliminate this problem. Needless to say, there is a lot more to the topic of grounds, safety, galvanic and stray current corrosion. Hence the recommendation to seek a professional.

ok that makes sense..thanks.

it ties in with what i was considering as a solution anyway, which is to remove the inverter wiring form the electrical panel entirely and use the outlets on the side of the inverter for the couple items that need the 120v.

it does seem to me that the problem is with the inverter and not the rest of the wiring. your explanation of the dangling ground makes sense.

[TheScarab]

@popeye...

BLOW ME (down)

agaigaigaigai

[hellosailor]

Scarab-
AC wiring isn't all that hard but as Bill mentions, it can kill you. The bigger problem may be that there's really no way that any assumptions can be made safely about what the old wiring is. Whether it was all wrong, or kludged, or ever working at all. There are plenty of books and web sites that can bring you up to speed on AC wiring and the guys in many hardware stores or chandleries can also help you out, sometimes there are retired licensed electricians among them.
What I would suggest is that there is only one way to work safely with what you have. Starting with the AC "dock" connection cord, the socket in your boat that it goes into, you want to draw a diagram of what you have or want, with every device shown on it, and every wire connection to every device. It doesn't have to be a formal schematic but it should show everything.
Then you sit down and start comparing to the books to make sure you have all the necessary parts, like a GFI device mounted up close to the deck connection. A double breaker on the AC panel. And properly rated parts, wires, boxes, for the whole system.
There are some really simple things that can and should frighten the hell out of anyone playing with electricity. A friend of mine asked me to help him out with a kitchen light (came with his used house) that hung on a chain. The light socket was wired up with what might have been speaker cord, not AC line cord. First clue, speaker cord isn't rated for the voltage. Second clue, he swears it wasn't him that used the hanging chain to carry the neutral (return, white) wire down from the ceiling box, and it wasn't him that used a wire nut to connect BOTH wires in the speaker cord together to carry the black (hot) lead down. But the way it was set up? It could have easily burned the house down or electrocuted someone trying to change the bulb. AC "faults" can turn "that'll work" into a funeral real fast, so by all means feel free to DIY on the project, but the only safe assumption is that a guy named Bozo did some of the prior work, and you can't assume anything there isn't a land mine waiting to kill you.
Pencil and paper, sketch it all out before you do anything else. They're cheap enough.

[CarinaPDX]

If you don't have the money, and you don't have someone to help you, then don't use the AC system until you do. Which is to say, if you have a 30A to 15A/20A adapter, then attach that to the end of the shore power cord, and attach a power strip (with internal 15A breaker, very common and cheap). Then plug in things there. For a few dollars more you can get a 30A plug, duplex outlet, and two power strips to get the full 30A out of the supply. This will also give you power while you are working on the AC system, and is sometimes useful for using tools on the dock. Home Depot or Lowes will have the parts, and a lot cheaper than the marine store.

[TheScarab]

yeah, that's what i'm doing right now (more or less)

just concerned about the dangling wires etc

right now there's no power to the a/c system

but i'll fix it. that's how we learn, right?

been shocked before. don't intend to do it again, but not going to run scared.

it's like saying 'don't mess with a gasoline engine because gas is flammable'....

little common sense, little patience, lotta thinking and discussing...things will work out