Galvanic isolator DIY

[skipperdude]

Regarding a galvanic isolator.
I have been doing some research on a Galvanic isolator I built myself

http://www.yandina.com/acrobats/GIDIYAssy.pdf

The question is would you trust a home made one as compared to one bought at a Marine store?

SD
__________________
If you can't repair it maybe it shouldn't be on the boat

 

[TedB_BC]

Home built will work. The down side is it will not meet ABYC standards. The home built unit does not have a monitor to show that the unit is working correctly. If the unit fails in an open condition without you knowing it you have a dangerous condition of no ground between the main AC panel and the marina shorepower source.

Ideally you should have a fail safe galvanic isolator to meet ABYC standards. They are not cheap however.

 

[skipperdude]

Do you think a monitor could be installed. i.e. a small light that would trip and come on?

 

[boatpoker]

I visited your link .... Never hire a marine electrician or buy electrical equipment built by someone who uses the term "electrolysis" incorrectly.

 

[Egregious]

I visited your link .... Never hire a marine electrician or buy electrical equipment built by someone who uses the term "electrolysis" incorrectly.

Galvanic Corrosion is what happens to your running gear. Electrolysis is what your wife gets to remove hair from her legs.

 

[skipperdude]

OK so how does the improper use of a term affect the isolator.

I am not using a Marine electrician or buying any electrical equipment pre fabricated that is.

I guess the real question is will this thing work or not.

Or is it just the old don't flip a breaker call an electrician or don't tighten the pipe call a plumber.

Sd

 

[TedB_BC]

Light for a monitor

As the isolator is connected to the ground wire there will be no power so a light as a monitor is probably out. What you would need I think is to monitor the continuity of the circuit.

 

[boatpoker]

The point is that if the designer of a piece of electrical equipment does not understand the terminology of his chosen profession, what else does he not understand about electricity. He also states on his site that a capacitor is optional under ABYC (not true) and uses that to suggest you buy a capacitance isolator from him. Your call ... but I prefer to buy electrical stuff with a UL mark on it.

 

[RT Firefly]

Greetings,
Mr. Egregiuos.

Definition of electrolysis

 

[Insequent]

If you have insurance, check with them whether you are still covered against a fire if you have installed home-made electrical equipment. If they say yes, get it in writing. But I wouldn't fancy your chances if you ever needed to claim......

 

[Larry M]

SD: I say go for it. How many things do we have on our boats that do not follow ABYC guidelines?

The idea of adding an indicator light makes sense although I'm not sure how to add one.

Yandina has been around for a long time with some good ideas.

Yandina Marine Electronics

 

[RickB]

Greetings,
Mr. Egregiuos.

Definition of electrolysis

Not to mention that galvanic corrosion can occur even when there is no electrical power supply within a hundred miles of the boat. It was a problem on copper sheathed ships in the 1700s. They did not use galvanic isolators but I doubt that was the cause of their corrosion problems.

Galvanic corrosion is caused by dissimilar metals in an electrolyte.

Electrolysis (or more properly in this context - electrolytic corrosion) is caused by electrical current acting on metals in an electrolyte.

So who is it that can't be trusted since he used the wrong term?

 

[av8r]

A Blue Seas 120V indicator LED connected between the ship's main AC bus and the ship side of the isolator will light if the isolator is working and will go out if the isolator goes to an open state. A second LED connected to the shore-side of the isolator would show if the failure is in the isolator or the shore-power connection or supply.

 

[boatpoker]

Monitoring is not required (ABYC) if a newer type failsafe isolator is used.

 

[TedB_BC]

LED indicator light

A Blue Seas 120V indicator LED connected between the ship's main AC bus and the ship side of the isolator will light if the isolator is working and will go out if the isolator goes to an open state.

av8r
I am having trouble wrapping my head around this. How will this work on the ground wire? Power wire I can see. AC will still work with only the hot and neutral.

 

[av8r]

The indicator shows the main is hot.
It should be hot to either neutral or ground since the neutral should be grounded at the source.
If the light connected to the ship side of the isolator goes out it shows there is no longer a connection between theground and the neutral

 

[skipperdude]

It would seem that before someone came up with a factory ABYC approved Galvanic isolator. Most folks just made their own.

I think the componets are the same. Or at least the concept is.

If you didn't have an isolator would it be any different than having one fail? Would you still you have a dangerous condition of no ground between the main AC panel and the marina shorepower source

Sd

 

[rwidman]

If your boat does not have a galvanic isolator and you are skilled enough to follow the directions given to build and install one, you will be better off than if you leave your boat without one. Even if there's no indicator light. Older isolators had no indicator light and the ABYC police don't come around and inspecting and condemming boats.

Installing a home made galvanic isolator will not void your boat insurance.

That said, I have the capability to build one, yet if mine were to fail, I would purchase and install a factory made, ABYC compliant isolator.

 

[skipperdude]

Just not the DYI kind of guy eh?

Or would you care to elaborate on your statement?

just curious.

SD

 

[rwidman]

Just not the DYI kind of guy eh?

Or would you care to elaborate on your statement?

just curious.

SD

Me? I was an electronic technician for over thirty years and I have built things far more complicated than a galvanic isolator. Far more complicated. In many cases, I also designed them before I built them.

It's just that I am retired, no longer have a source of quality parts (Radio Shack is not a source of quality parts), and just don't think it's worth the time and effort to cobble up something that's commercially available at a reasonable cost. Remember, you still have to buy the parts.

 

[skipperdude]

A couple of Bridge rectifiers at about $5.00 each and a hunk of aluminum angle and some wire about a $20.00 investment vs a couple of hundred for a factory one.

It does exctly the same thing.

Not looking for permission here. It is just me. I like to know how things work and why.

Great idea Av8r of a light on the unit (constant on) just to tell me the thing is doing what it is supposed to do is a great idea.
I will install it this weekend.

Such a simple thing.

Sd

 

[RickB]

If the light connected to the ship side of the isolator goes out it shows there is no longer a connection between theground and the neutral

Or, more likely, it will continue to flicker intermittently because the reason the GI failed is likely from a ground fault taking out the diodes and that ground fault now has no way to go directly to earth and is energizing the housings of every piece of AC equipment, the engine block, and through that to the negative side of the DC distribution circuit.

It only flickers intermittently because the seawater that now serves as a conductor between all the parts connected by that pesky green bonding wire and the earth can be kind of an iffy conductor. Someone touching the dock and a grounded metal part of the boat would allow it to glow properly.

 

[Marin]

SD--- We had a brand-name galvanic isolator installed on our boat many years ago. They are actually not very expensive at all. What IS expensive is an isolation transformer.

A galvanic isolator if properly built and installed will protect your boat from leaking current in the ground power from the dock. Like if some other boat or a dock wiring fault is allowing current to get into the ground wire.

But a galvanic isolator will not do anything to protect your boat from stray current in the water itself. If such a current is present in your slip, in extreme circumstances it can make short work of propellers, through hulls, etc. The only way to combat this is with an isolation transformer and they are major dollars.

 

[skipperdude]

The only stray current I have experienced is what I think was a boat over zinced

It turned my propeller white and it would not scrape or sand off.

I never figured out what it was but a year later the prop is fine. No white

SD

 

[rwidman]

............. The only way to combat this is with an isolation transformer and they are major dollars.

So why not make your own? All you need is a bunch of wire and some iron cores.

 

[RickB]

Now you're talking Troll old boy!

 

[skipperdude]

So why not make your own? All you need is a bunch of wire and some iron cores.

Ha! Ha! come on man.

As far as that go's just build your own boat.

We are talking apples and oranges here.

A galvanic isolator is a simple thing. Off the shelf componets at any electronics store.

sd

 

[RickB]

Be careful SD, they don't like it when you crack their ricebowls or bust their myths.

Can't be letting normal people look behind the curtains and smoke screens.

 

[av8r]

Or, more likely, it will continue to flicker intermittently because the reason the GI failed is likely from a ground fault taking out the diodes and that ground fault now has no way to go directly to earth and is energizing the housings of every piece of AC equipment, the engine block, and through that to the negative side of the DC distribution circuit.

It only flickers intermittently because the seawater that now serves as a conductor between all the parts connected by that pesky green bonding wire and the earth can be kind of an iffy conductor. Someone touching the dock and a grounded metal part of the boat would allow it to glow properly.

Thus the boat and shore will be turned into the two sides of a large electrolytic cell, producing hydrogen, oxygen, and chlorine gas.
A prudent mariner would avoid a vessel with streams of bubbles coming from the metal fittings below the waterline, especially if accompanied by a distinct chlorine odor. A rapid departure of the area would be in order.

 

[Northern Spy]

I visited your link .... Never hire a marine electrician or buy electrical equipment built by someone who uses the term "electrolysis" incorrectly.

I believe that Anne-Marie (Yandina) is a retired electronics engineer from Australia.

She has been quite prevalent in on line forums and e-mail groups for a long time. She has some interesting and strong opinions about the ABYC.