Galvanic Isolator's

[dignity]

Galvanic Isolator\'s

I live on board my steel barge, 90% of the time I'm hooked up to shore power, you hear so many horror stories regarding electrical corrosion of steel hulls, is it worth fitting a Galvanic Isolator? Or are they just another gimmick for the chandler to rob us of our hard earned cash!

 

[Guest]

Re: Galvanic Isolator\'s

If you live in a "hot marina" where there is a lot of voltage being leaked into the water around you....it would be in your best interest to install a galvanic isolator.

I was having a problem in a marina I was in with my zincs corroding away too fast and I installed a galvanic isolator and the problem was corrected.

Galvanic isolators are worth the investment. If you buy one....make sure you get one that is properly rated from your Amperage rating. I didn't note where you were from...but here in the US....a 30 Amp hookup uses one, and a split 50 Amp uses two.

On the other hand...if you are not experiencing a problem with rapid corrosion on your zincs or other hardware....I probably wouldn't be too worried about the issue. But on the other hand.....if you travel about to different marinas, or you just want to be safe.....I would protect my boat with the Galvanic Isolator.

There have been numerous articles written by noted authors on these devices so a yahoo or google search should pop you up plenty of reading material on the subject.

Reality is the cause of all stress!!

 

[colin_jones]

Re: Galvanic Isolator\'s

Adverc have an interesting galvanic isolator at a sensible price. There is also some info on their .co.uk website. If this is not enough, give them a call. you will find them to be very knowledgeable and very helpful.

 

[castlevar]

Re: Galvanic Isolator\'s

we also live on a 13 mtr steel motor boat presently in the algarve moving hopefully next year to the med .
i have fitted a galvanic isolator according to reports they work very well.
but i have also fitted an earth device to my prop shaft as i was un happy about how good the earth was.
I fitted a copper brush bearing against the shaft to gearbox coupling use a brush holder out of an old electric motor.
after that all you can do is hope everything is ok you have done your best.
best wishes geoff

geoff

 

[Gunfleet]

Re: Galvanic Isolator\'s

Does an rcd still work if it's downstream of a galvanic isolator?

 

[HaraldS]

Re: Galvanic Isolator\'s

Yes it does. In fact I would always add an RCD if I was using a galvanic isolator.
That is for two reasons. A small groundfault, with some smaller current flowing through the isolator, would render the isolator ineffective as the DC component it is supposed to block would ride on top of the AC.
All the galvanic isolator does, is to block current flow for voltage potentials lower than 1.4 Volts (two diodes in series). That is good enough for galvanic voltages from dissimilar metals. A small ground leak on AC however would pass and may go undetected for a while if there was no RCD. (Unfortunately it even may do so, without the RCD tripping if it doesn't reach the RCD threshold.)
The second reason is that with a real serious ground fault, your isolator has to take a huge current, and it depends on the price of the isolator for how long it will cope with that. Relatively cheap diodes can carry high current for some time before overheating and definitely long enough for the RCD to trip and relief them.

The galvanic isolator may however not help in a "hot marina". Faulty installations on other boats or in the marina, may well cause electrolytic (not galvanic) voltage potentials far above the isolator thresholds. The only more effective protection would be an isolation transformer.