Narrowboat Electrician - Galvanic Isolation

Little job on NB Perfik
Simple task to ad a galvanic isolator
#narrowboat #electrical #help
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[@Chris_In_Texas]

Its funny, here in the USA, the AYBC (American Yacht and Boat Counsel) required boat builders to install both galvanic isolation and had to have automated testing to make sure that it was still in working order, as there is no way to know if its working or not. The systems would test the unit when it turned on and every four hours after that. So when you plugged into shore power the automatic testing would start. The way it tests, it would actually introduce a ground fault into the AC wiring / shore power system. Fast forward a number of years, now our electric codes were updated that requires (GFCI) ground fault circuit interrupter on all marina outlets and shore port connections. This was in direct conflict with AYBC for testing of the GI system. So as soon as you plugged your boat into shore power it would trip the marina shore power connection. The only fix is to disable the testing, as the marina wasn't going to remove the GFCI breakers from the system. I have seen galvanic corrosion on boats in a marina and it can be a huge mess. Just about all of our boats here are fiberglass, so what would be attacked was any metal on the underside of the boat. You never knew who's boat was the "leaking" boat that was eating all the anodes off the boat until they moved away. Keep up the good work sir.

[@narrowboatelectrician]

That is really interesting. On that type of vessel there are materials like magnesium and aluminum which gets seriously eaten by galvanic corrosion. Our steel hulls suffer too but at a slower rate, having said that I saw one boat that wasn't very old and was severely corroded all down the one side. We fit sacrificial anodes to the steel hull (welded or bolted) that sit at the same potential as the hull. These get taken first if there are galvanic currents present, and we change them when it dry dock where needed. We have RCD's on our bollards too (I think they sound the same as your GFCI) if there is more than 30mA difference between current on live vs current returning on neutral, they trip. Great comment that.

[@brutwinky6492]

Good video, cheers much appreciated.

[@narrowboatelectrician]

Thank you.

[@LoisDavidsonArt]

Looking forward to future content, many thanks, I've subscribed

[@narrowboatelectrician]

Great, thanks Lois.

[@TheBobCast6056]

Very interesting, first electrical job I did on my boat was put in a galvanic isolator. Now next time I am on my boat I need to check to see if there is an earth to the hull. I suspect not. Thanks so much for these videos.

[@narrowboatelectrician]

Its good that I have got you looking for that hull earth. Its all about that kind of thing. Glad to have you over here.

[@davidcook380]

Great Stuff Mart, You are so good at explaining things , l know about electrics but find it hard to explain it in laymen's terms .

[@narrowboatelectrician]

Cheers David, I like to try keep it plain and simple. I don't feel the need to baffle everyone, keep it real.

[@raymondrobertson3869]

Thanks for another great video. Also thank you very much for your reply yesterday. I know you are a very busy guy so your reply was appreciated. Keep them coming 👍🏴󠁧󠁢󠁳󠁣󠁴󠁿

[@narrowboatelectrician]

Thanks Raymond, an will do.

[@REWYRED]

That is interesting! Never would of thought but ya I see how things would start to corrode if circulating currents were allowed to pass. You mentioned isolation transformers: we use / used them in hospital to isolate medical equipment from ground... More common for the isolating means to be in the equipment rather than the building wiring now.

[@narrowboatelectrician]

I am glad you found it interesting. We can use isolation transformers in a manner to block galvanic currents. We are not trying to isolate the supply, we rely on the RCD's to operate in fault conditions. I would imagine there are a whole host of differences in the medical world and high quality too.

[@superotterboy7937]

Just came across the channel and have to say, great video! Most of my viewing on youtube are technical, electronics and engineering channels these days and was delighted to see yours pop up on my homepage. Keep up the excellent educational content!

[@narrowboatelectrician]

Thanks you for that, glad you found me and that you like the channel. I'll do my best to keep it up!

[@chilledoutpaul]

Galvanic's This is also another reason back in the 60's cars changed from positive earth to negative earth or ground; Because of the cars positive ground and Worlds ground potential; when it rained the cars positive and the worlds ground changed the rain to an electrolyte and the cars use to rust away with respect to the worlds (the earths 🌍) ground potential

[@narrowboatelectrician]

Spot on mate. We also go a step further, that all systems must be two wire (Feed and return) so no current flows in the hull. Thanks for the comment, its a valid comparison.

[@srg0075]

Thanks for the video on this important subject, but what I don't get is why these devices are so expensive, when they are just essentially a couple of say inexpensive 16A diodes back to back?

[@narrowboatelectrician]

Case costs more than whats inside!

[@davidsedlickas8222]

I would prefer an isolating transformer than galvanic isolator.

[@narrowboatelectrician]

Yes David, no doubt they are a higher lever of protection. But not everyone wants the price tag. 90% plus narrowboats have galvanic isolators that offer more than adequate protection.

[@holmesjunction]

Hi, YT threw up your channel and it looks interesting, so have subscribed. I only I have one comment that may help viewers if they have a go themselves. It concerns the nuts on the terminal posts. Just tightening the main nut down is NOT best practice. Always use TWO spanners to pinch up the connections between the two nuts. Just tightening the main nut could cause the terminal to rotate/break. It looks a good quality unit, but you can never tell how the terminal is fastened inside (unless you know better?) and there is always a possibility of braking internal connections (and guarantee?). Cheers.

[@narrowboatelectrician]

Hi of course you are correct. I had already tightened the base but as they are always lose on the Victron galvanic isolators. The problem is people tightening to tight, by mechanical types, they only need a bit of force to be adequate.

[@thenorthproject8465]

Great channel and information, keep up the good work :)

[@SirTeabag]

So my question is - which side of the galvanic isolator does the earth to hull cable need to be? I assume it must be the "boat" side - from the consumer unit earth bar?

[@narrowboatelectrician]

Hiya, yes any boat earth needs to be on the boat side. The only connection to the shore side is the incoming earth.

[@ItsMe-xr3bq]

Hi. Great videos do you design wiring diagrams for narrow boats if you are given the layout Thanks

[@narrowboatelectrician]

Yes I do, contact me through [e-mail]

[@anenglishmaninbrazil3212]

is not stripping the cable in that manor not altering the cross section of the conductor because it will be ever so slightly stretched

[@narrowboatelectrician]

Hi, welcome to the channel. Us sparkies have been stripping cable that way for years, bigger stuff would be with a knife. Even the proper strippers hold the insulation, dig in and pull.

[@ryehiker]

At 3:00 mins into the video - the phone above your left shoulder. How exactly is that wired in?

[@narrowboatelectrician]

Hi Rye, sorry never worked on it or installed it. I am back on that boat next week so Ill take a look.

[@ryehiker]

@@narrowboatelectrician Later in the clip you mentioned that the boat had spent much of its life in a marina, so maybe a landline was a service along with electric way back when? Also, love all of the metal, I am seeing Maiden here in Ohio, USA in October!

[@thepilgrim4473]

What a great channel this is! Subscribed! A quick question: does the boat ground/earth wire go directly to the hull (anywhere?) straight from the common ground bar or from the galvanic isolator itself? Also is there any kind of digital gauge/device that would enable monitoring from the electrical panel, or does a GI basically last forever? Keep up the fantastic work, looking forward to the next episode.

[@narrowboatelectrician]

Im so glad you are enjoying the channel, seems like I have hit on something, which is great as I want to share knowledge (not baffle people with science) he earth to the hull can either come from the consumer unit earth bar or the boat side of the galvanic isolator. This can go to anywhere on the hull as its all welded together, I often drill and tap the engine support rails, ensuring the paint is removed, There is a "thing" with galvanic isolators, how do you know they are healthy? Some new ones are coming with a gauge that identifies any current flowing. They can be tested with a simple multimeter if there is a diode function. It has been known for GI's to fail under high current fault conditions.

[@thepilgrim4473]

@@narrowboatelectrician excellent, thanks for the reply! We are having a “hybrid” propulsion boat built in November which, for me at least, involves some scary electrickery! I suppose it’s a matter of trust that the correct wire gauge, fusing, loads etc etc are being used. Perhaps that would be a good future vlog for you to cover ( you can practice on our boat! )? Your vlogs on parallel/series batteries and solar are terrific! Keep up the good work!

[@narrowboatelectrician]

@@thepilgrim4473 thanks for that. I would be fairly confident that a factory built boat would have correct size wiring and fusing. If that builder has good electrical practices. Boat fitters and self builds tend to have more issues in my experience.

[@thepilgrim4473]

Fantastic channel! Count me in as a subscriber! A quick question: do you ever install isolating transformers on narrowboats? Wouldn’t it be a great idea given the boats are entirely metal, especially when moored in a marina? Btw our boat is just going into build, so I’m trying to do everything right from the outset. Keep up the most excellent work!

[@narrowboatelectrician]

Hiya, rare on narrowboats, more common on big Dutch and widebeams, but even then only a few percent go to that level.

[@royholmes4327]

Hi does galvanic isolator replaced the anodes A Narrowboat

[@narrowboatelectrician]

Hi Roy, It does not replace, It helps to protect the hull and them from galvanic corrosion.

[@danhollifield]

You'll get a laugh out of this: I jut started the video, and when you said you need to get to the ground wire from the shore power, my electricity went out here at the house! ROTFL! Re-watching now that the power has been restored.

[@narrowboatelectrician]

Spooky Dan, I had no hand in that lol.

[@andy_nye]

Very informative .. thanks .. Will subscribe

[@narrowboatelectrician]

Thanks for the sub! Glad you liked it.

[@steveohagan665]

Hay mat just come over from moonshine . this looks interesting hope it all goes well . O yes iv just subscribed .

[@narrowboatelectrician]

Thanks Steve. Appreciate it.

[@fartbag22]

Hi Mart.. If your not 100% sure the boat earth is earthed to the hull how do you know the galvanic isolator is working? or am i just being thick. cheers

[@narrowboatelectrician]

Hi Nigel. A continuity check is the only way. If the earth isn’t on the hull there won’t be any galvanic corrosion. I did check with multimeter that the hull has an earth. It’s only a few weeks and all the electrics will get taken out. Was done more for owners piece of mind really.

[@optimist3580]

Hi Mart, when do you think we will start saying 230v instead of the 30 year out of date 240v? I know I still use 240v when describing mains voltage, it’s a very hard habit to drop. Good vlog on galvanic protection, I feel marinas should check that boats are compliant if they are long term residents.

[@narrowboatelectrician]

I never even think about it. Doubt general public even realise it’s changed! I’ll try and be more accurate as that’s the best policy. Cheers, glad you are enjoying the channel, and keep those comments coming.

[@jonka1]

I suspect that 230 is just a figure to quote to satisfy some directive somewhere. Our house supply is 243 + - a couple of volts. We have our own transformer on a pole and the supply company considers this voltage to be normal.

[@optimist3580]

@@jonka1 so your supply voltage of 243 is within the UK nominal supply voltage of 230.

[@havoctrousers]

if it makes you feel better, the actual transformer output of substations in the UK did not actually change when we harmonised with the EU. You will still probably get around 240V out of your house supply. We just use 230V now for any kind of power calculations. The tolerance for home supplies is -6%/+10% or around 217V-253V I believe.

[@optimist3580]

@@havoctrousers yes I know, thank you

[@CaptainK007]

No isolation checks before starting work on a system?

[@narrowboatelectrician]

Hey Steve, I’m not in industry anymore. I have worked to protocols all my life. Breaking into an earth, for me does not require me to isolate. Good point that I may tell others to do that though.

[@CaptainK007]

@@narrowboatelectrician hi. It’s not you or me but people will copy what they see. Poking around an installation that may not have all its wires tucked up, unplugged from shore power and the inverter has kicked in. I worked in a boatyard where one of the “Craftsman” watched a sparkie disconnect a battery bank and remove the batteries so he could build a bigger battery box. The owner offered him a few bob to put the original batteries back in to save sparkie hours. It went well for the first couple, the next one cost him his three middle fingers of his right hand. Plus making a right mess of his hand. I as you will have seen “that’ll do stuff” that makes you wonder while their still alive or haven’t burnt down. They walk amongst us. 😎🍻🍻

[@niklar55]

😊👍❗ I have no experience of boat electrical system regulations, but; Would you consider using Pyro cable on all the 240 volt circuits on a boat worthwhile? .

[@narrowboatelectrician]

Absolutely not mate. Use arctic flex.

[@niklar55]

@@narrowboatelectrician Would you give your reasons please? .

[@narrowboatelectrician]

@@niklar55 pyro isn’t flexible. Boats move, vibrate and stretch. Damp could get into the mineral insulation and cause a short. Arctic flex is tried and trusted and a standard in the industry for the 240v circuit. That’s my opinion mate, others may differ.

[@niklar55]

@@narrowboatelectrician OK, thanks for your response, and your opinion. When I was training, the end fittings of the Pyro cable were sealed against damp, so that shouldn't be a problem. It's also flexible enough to bend around most corners, but won't be floppy and sag. It's no more vulnerable to vibration than copper fuel pipes, in fact less so, as there are no 'olive' connections. It's totally fireproof, under normal conditions, unless it gets hot enough to melt copper! We also hammered a piece flat, to about 1-2mm thick, and it still didn't short, so a little stretching wouldn't be a problem that a single coil couldn't take care of. So, I think it would be superior to plastic cables in nearly all situations. The only drawbacks that I can see, is cost, it's damned expensive, and it's more work intensive to install. I posed the question, because I wondered if there were specifications in the regulations that would prohibit it in any way. It seems there is not., or you would have said. So, thanks again. .

[@narrowboatelectrician]

@@niklar55 yes, I’ve worked with Pyro. Up to you, but I can’t see the advantage, especially factoring in cost and effort. Wiring a boat is expensive enough.