Which Galvanic Isolator?

[Luther]

I need to install a Galvanic Isolator but Googling hasn't yielded much in terms of reviews & recommendations.

I don't understand the difference between a 30amp and a 60 amp (nor the very small price difference between them).

Boat runs on 50 amp shore power. Installing a GI appears simple...

Could anyone recommend an appropriate Brand/Model?

Cheers,

[a64pilot]

I think as long as you stay with an established name brand, you can’t go wrong.
As a swag most any mid priced one Defender sells is most likely good.
Very simple thing actually and if like mine it’s mounted where it will normally never be seen.
It’s my understanding that if you have a 30 amp Boat, a 30 amp isolator is sized for you, I don’t think it would be bad to fit a bigger one, but why?

Not saying buy from Defender, just that they seem to do their homework and seem to sell good products.
Mine happens to be a Promariner, which means nothing of course.

[smac999]

if the boat has a 50a shore plug then you'd need a 50 or 60a isolator.

you want a fail safe one. this one would be fine

60 A ProSafe Isolatr FAIL SAFE | ProMariner

[CarinaPDX]

A galvanic isolator blocks DC electricity from entering the boat, thus preventing setting up a galvanic cell (or stray currents) that might cause loss of underwater metals. Galvanic isolators are part of the ABYC recommendations, and are very desirable - as far as they go. A better approach would be to install an isolation transformer, which not only blocks DC currents but also isolates the AC system and thus avoids some safety issues. Isolation transformers can also have extra taps for stepping up/down the voltage; mine can take either 110V or 230V input and output either one as well. This is very convenient for American boats visiting 230V countries. Another feature is to provide an optional boost to the voltage on some units. If you are in a poorly-wired marina (not uncommon) and are only getting 100V at the dock a boost might bring the voltage back up to 110V for operation on the boat. All this costs money of course - an extra $1k or so more than an isolator for a basic 50a transformer and up from there.


Greg

[GordMay]

Galvanic isolators are covered by ABYC Standard A-28 GALVANIC ISOLATORS - Current Version: 2014
2008 Version ➥ http://www.plaisance-pratique.com/IM...s_Standard.pdf

Pro Mariner ProSafe FS (Fail Safe) Galvanic Isolators
➥ ProSafe FS Series | ProMariner

Newmar Galvanic Isolator #GL-50
➥ https://www.newmarpower.com/wp-conte...al-GI-3050.pdf

Yandina Galvanic Isolator #GI-50N
➥ https://www.yandina.com/acrobats/GalvOwnManual.pdf

DEI Marine Fail Safe Plus 50/60 Amp Galvanic Isolator #DEI-GI-50/60A-FSP
➥ https://www.deimarine.com/

[flee27]

I understand te failsafe part of units like the Pro Mariner. Is the Yandina just as effective other than the fail safe part? Big difference in price. As long as I tested a non fail safe unit regularly would it protect just as good? Don't mind the $250 for the Pro Mariner but like the $75 for the Yandina if performance is the same (other than fail safe).

Thanks
Foster

[goboatingnow]

It’s needs to be failsafe or have a monitor circuit to indicate failure

[CharlieJ]

Yandina is not compliant with ABYC A-28, thus the difference in price.

[CharlieJ]

@CarinaPDX #4

A galvanic isolator blocks DC electricity from entering the boat, thus preventing setting up a galvanic cell (or stray currents) that might cause loss of underwater metals.

Stray current corrosion is generally the result of battery voltage in contact with underwater metal components. A galvanic isolator will block up to about 2VDC but will not block DC stray current greater than this threshold.

[YANDINA]

Originally Posted by CharlieJ

Yandina is not compliant with ABYC A-28, thus the difference in price.

What's your problem Charlie, did you pay too much for your isolator and got p!ssed?

The Yandina Galvanic Isolator IS fail safe and exceeds ABYC specifications.

It has been on sale now for over 18 years, all with unconditional warranty. To date there has not been a single warranty claim for failure in the field.

No isolator is "fail safe", they are only fail safe when used correctly in a shore power connection using the correct rating circuit breaker. Our test set, that tests every one we make to ABYC specifications, can be set high enough to fail any "fail safe" isolator.

Yandina Galvanic Isolators were manufactured for and marketed by West Marine for about 12 years and West Marine had them certified by an independent laboratory before accepting them.

We are the only manufacturer to offer a 2.5 volt isolator for use on Aluminum boats or for use in aggressive docks with excessive leakage.

[CharlieJ]

What's your problem Charlie, did you pay too much for your isolator and got p!ssed?

Nope. Just wanted to warn the novices that your GI is not compliant with A-28.

No isolator is "fail safe", they are only fail safe when used correctly in a shore power connection using the correct rating circuit breaker.

What does the rating of the shore power circuit breaker have to do with a GI. The safety ground wire is not broken by the circuit breaker. Strange comment.

We are the only manufacturer to offer a 2.5 volt isolator for use on Aluminum boats or for use in aggressive docks with excessive leakage.

Being able to block 2.5VDC is nice marketing hype but it has nothing to do with the physics of the system. Magnesium anodes provide the highest potential of the anodes used in cathodic protection systems. A Mg anode in saltwater will produce about -1600mVDC against a AgAgCl reference cell. That is all a GI has to block; 1600mVDC.

[YANDINA]

Originally Posted by CharlieJ

Nope. Just wanted to warn the novices that your GI is not compliant with A-28.

Just 'cause you say so? WHAT EVIDENCE? PROVE IT or apologize.

What does the rating of the shore power circuit breaker have to do with a GI. The safety ground wire is not broken by the circuit breaker. Strange comment.

The circuit breaker limits the maximum current that the ground would have to carry in the event of a short to ground. We test at 75 amps for every 50 amp Galvanic Isolator we make in order to meet with ABYC requirements on a circuit with a 50 amp breaker. Without that breaker the current in a short is only limited by dock and boat wiring which could easily overload the diodes even though they are fail safe.

Being able to block 2.5VDC is nice marketing hype but it has nothing to do with the physics of the system. Magnesium anodes provide the highest potential of the anodes used in cathodic protection systems. A Mg anode in saltwater will produce about -1600mVDC against a AgAgCl reference cell. That is all a GI has to block; 1600mVDC.

Any AC voltage in the ground, which is very common on docks, is added to the DC you are trying to block. When the AC voltage is opposite to the DC you are blocking it is increasing protection but when the half cycle is the SAME polarity of the DC it only takes 1/2 volt of AC on top of typical 0.6 volts DC to exceed the isolator. In worst case this can reduce isolation up to 50%.

Responses are shown above in the QUOTE.

[CharlieJ]

@Yandina
No need to yell. Are your GI's compliant with A-28 and if so, what third party laboratory performed the certification?

Reference: ABYC 28.5.1 Galvanic isolators shall be tested by an independent laboratory to establish compliance with this standard.

Any AC voltage in the ground, which is very common on docks, is added to the DC you are trying to block.

It is true that there is often AC present on marina safety ground systems.

When the AC voltage is opposite to the DC you are blocking it is increasing protection but when the half cycle is the SAME polarity of the DC it only takes 1/2 volt of AC on top of typical 0.6 volts DC to exceed the isolator. In worst case this can reduce isolation up to 50%.

The parallel capacitor (your units do have a parallel capacitor, don't they?) will shunt any AC present on the safety ground wire around the diodes.

ABYC A28.5.4 Galvanic isolators using diodes shall use a non-polarized capacitor(s), or equivalent method of meeting the requirements of A-28.12.4.

[flee27]

Being the one who asked the question I would like to say thanks for the replies, but...

I understand how a GI works and why they are important to have. I also understand why the fail safe is a desirable feature of the GI. I was just curious about the overall quality of the unit, ignoring the fail safe feature for the sake of discussion.

Yandina might make a great product but I will say if the person responding as "Yandina" is really associated with the company they really need to think about a more tactful why to defend their product. The responses have been far from professional or educational and doesn't promote a good image. Facts are facts. All the things discussed above should be easily clarified and validated.

Thanks for all the knowledge
Foster

[goboatingnow]

Just put in at IT