Generator earthing

[tomandsophie]

We've just got a nice shiny new genny - 2.3kva to run our washing maching (and before anybody ventures the question... yes, it will power it fine, we've tried it with a friend's 1.8kva genny and all the cycles went well). I haven't run it yet, as it says in the manual that it should be earthed. There is a little attachment screw on the front to attach an earth lead to. I have never seen another genny being earthed - certainly nobody along the cut where we are has done it. I guess earthing it to the boat is not a good idea. The only way I can think of is to run a lead out to the bank. Is it worth it? Or is it just one of these things that the manufacturers have to put in the manuals like a kind of disclaimer in case anybody sues them?

[Richard Bustens]

Is this a free standing Gen set to sit on the bank? as i thought you had a inbuilt one.?

[tomandsophie]

No, we have an inverter, but it turns out it won't run our washing machine. Very annoying. This genny is freestanding to go on the bank.

[Richard Bustens]

Dont know for certain but if it is on the bank i dont think it would matter but i supose there should be a steel spike in the ground but if you stand it on the boat i think it should be earthed to the hull.

[Gary Peacock]

I would earth it to the hull in the same way an on board generator is done after all you are bringing an external AC source onto the boat in just the same way your shoreline does. Larger generators usually have an earth-spike to drive into the ground this provide a earth ground point for the generator chassis and earth conductor.

[DaveR]

I bought an earth rod from Screwfix (about 3 feet long complete with clamp connection) and drive that into the ground as far as I can reasonably get it.

 

Would it be worth while taking and earth from your shore lead connection (also via the galvanic isolator) and attaching that to an earth rod? However as you will only be running the genny for a couple of hours max. it may not be necessary.

[tomandsophie]

Most people I have spoken to simply have their gennies on the stern deck with no earthing system at all. Like you say, we're only going to be running it for a couple of hours (absolute maximum). What I'm looking for is whether or not it is actually dangerous not to earth it. Am I risking electrocution?

[John Orentas]

Most people I have spoken to simply have their gennies on the stern deck with no earthing system at all. Like you say, we're only going to be running it for a couple of hours (absolute maximum). What I'm looking for is whether or not it is actually dangerous not to earth it. Am I risking electrocution?

 

 

Tom.

 

If you have Earth Leakage Devices fitted, for them to function reliably you must connect an earth from the generator to the boat hull. If you have other 230 volt supplies, land-line or inverter, some thought must be given to ensuring that they can never be connected together in any way even for a millisecond.

[tomandsophie]

I'm still a little confused about whether or not I need to earth the genny. We don't have a shoreline and I'd like to keep the genny on the stern deck to avoid having to keep lifting it on to the bank (it's very heavy!).

I have been advised not to earth to the hull because of corrosion issues, and I have seen a lot of gennies along the cut which are on the stern deck without any kind of earthing system.

[John Orentas]

I'm still a little confused about whether or not I need to earth the genny. We don't have a shoreline and I'd like to keep the genny on the stern deck to avoid having to keep lifting it on to the bank (it's very heavy!).

I have been advised not to earth to the hull because of corrosion issues, and I have seen a lot of gennies along the cut which are on the stern deck without any kind of earthing system.

 

 

The general rule is, if it is made of metal and it has electrics on it. Bond it to earth.

[Gary Peacock]

I'm still a little confused about whether or not I need to earth the genny. We don't have a shoreline and I'd like to keep the genny on the stern deck to avoid having to keep lifting it on to the bank (it's very heavy!).

I have been advised not to earth to the hull because of corrosion issues, and I have seen a lot of gennies along the cut which are on the stern deck without any kind of earthing system.

 

If you haven't got the generator earthed shore side to a common electrical earthing point then galvanic corrosion will not take place. Even with a ground spike on the generator it would still be very unlikely.

[tomandsophie]

So you're saying that it should be fine then to run the genny on the deck and earth it to the hull, and galvanic corrosion should not take place?

[gaggle]

lets hope so because mine is on a carrier on the stern and it stays there permanent,it is metal sitting on metal.

[Gary Peacock]

So you're saying that it should be fine then to run the genny on the deck and earth it to the hull, and galvanic corrosion should not take place?

 

Yes you wont get any galvanic action that way.

 

Sam is going to put up a bit on his site soon about it.

 

But you can view largely the same article all be it a bit fragmented and rough HERE

 

Have a read and see if you get it if not ask for an explanation and I will try to help.

[tomandsophie]

lets hope so because mine is on a carrier on the stern and it stays there permanent,it is metal sitting on metal.

 

Our genny specifically says in the manual that it should be earthed. It wouldn't be metal on metal in our case as the genny sits on little rubber grommets. It has an attachment point for an earth strap, so maybe I ought to run a wire over to the bank.

I was wondering about attaching this wire to the mooring pin at the stern. I'm guessing that this should work as an alternative to the ground spike?

[Gary Peacock]

Our genny specifically says in the manual that it should be earthed. It wouldn't be metal on metal in our case as the genny sits on little rubber grommets. It has an attachment point for an earth strap, so maybe I ought to run a wire over to the bank.

I was wondering about attaching this wire to the mooring pin at the stern. I'm guessing that this should work as an alternative to the ground spike?

 

It wont do any arm but when you earth the hull that will actually become the earth for the generator.

[John Orentas]

Yes you wont get any galvanic action that way.

 

Sam is going to put up a bit on his site soon about it.

 

But you can view largely the same article all be it a bit fragmented and rough HERE

 

Have a read and see if you get it if not ask for an explanation and I will try to help.

 

 

Gary.

 

This whole thing about galvanic transfer is very debatable, but it can't do much harm if people want to believe it.

 

I do however think you should make it clear that concerns have been expressed about the use of 'Galvanic Isolators' by the people who know about these things, I would think twice before openly recommending their use. They effectively put a diode or two in series with your earth connection.

 

Earth bonding should be a DIRECT connection. If we did this in our household wiring it would be illegal.

[Gary Peacock]

Gary.

 

This whole thing about galvanic transfer is very debatable, but it can't do much harm if people want to believe it.

 

I do however think you should make it clear that concerns have been expressed about the use of 'Galvanic Isolators' by the people who know about these things, I would think twice before openly recommending their use. They effectively put a diode or two in series with your earth connection.

 

Earth bonding should be a DIRECT connection. If we did this in our household wiring it would be illegal.

 

The easiest solution is to unplug the land line if you are concerned about Galvanic/cathodic corrosion. The Americans are working on new legislation and specifications for galvanic isolators to increase safety, where they go we will also probably soon follow. The BEMF & US Power Squadron endorse the use of galvanic isolators and were doing so at least nine years ago, they don't build or sell them so I think we can call there views the accepted practice, the BMEF are the technical advises behind both BSS and RCD so do have a fairly trusted pedigree.

 

If you are worried about Galvanic corrosion but don't like the idea of diode based Isolation a much better and robust method is the way it is done in serious marine and industrial applications with the use of an Isolation transformer. Both major players in marine electrics field are gearing up at this moment to sell these to UK inland waterways market. I don't want to reinvent the wheel so you can read about them HERE this is probably a far better solution than four diodes but costs around £400-£1100 so I don't think there going to be the next big seller on the cut!

 

The bottom line is that the 2004 BMF report on corrosion that was worked on by both industry and universities concluded that Galvanic corrosion is a problem. I started this with the cheap easy solution the other two are really down to individual choice and budget if you want them.

[John Orentas]

The easiest solution is to unplug the land line if you are concerned about Galvanic/cathodic corrosion. The Americans are working on new legislation and specifications for galvanic isolators to increase safety, where they go we will also probably soon follow. The BEMF & US Power Squadron endorse the use of galvanic isolators and were doing so at least nine years ago, they don't build or sell them so I think we can call there views the accepted practice, the BMEF are the technical advises behind both BSS and RCD so do have a fairly trusted pedigree.

 

If you are worried about Galvanic corrosion but don't like the idea of diode based Isolation a much better and robust method is the way it is done in serious marine and industrial applications with the use of an Isolation transformer. Both major players in marine electrics field are gearing up at this moment to sell these to UK inland waterways market. I don't want to reinvent the wheel so you can read about them HERE this is probably a far better solution than four diodes but costs around £400-£1100 so I don't think there going to be the next big seller on the cut!

 

The bottom line is that the 2004 BMF report on corrosion that was worked on by both industry and universities concluded that Galvanic corrosion is a problem. I started this with the cheap easy solution the other two are really down to individual choice and budget if you want them.

 

 

I couldn't care less about what the Americans think, they only use 110 volts and their earthing regulations are totally different to ours.

[Gary Stacey]

Galvanic corrosion is a real issue, nasa believe in it, scientists believe in it (galvanic cell, galvanic series etc), people who build and install underground pipelines and tanks guard against it, seafaring boat types fit anodes to their engines to protect against it, larger boats use impressed current systems to prevent it, look up any website on corrosion and it will be listed, when it comes down to it corrosion is an electrochemical reaction, you only have to look at your average aged land rover to see its effects. The principles are very simple, the chemistry less so.

Edited January 11, 2006 by Gary Stacey

[dor]

Back to generator earthing: Practical experience!

 

I used to think that as long as the item you were plugging in to the generator was earthed to the generator, everything would be alright.

 

A few weeks ago I wanted to do a bit of welding on the hull, sticking a bit of rod over the front cratch drains to stop water running in. The generator & welder were on the towpath, and admittidly the ground was damp that I was kneeling on. I was holding the bit of steel with mole grips, and as I struck the arc, the moles went about 50 foot in the air as I involuntarily jumped.

 

This did make me reappraise the earthing requirements, and after that I would earth the genny to the hull with a jump lead and isolate the boat electronics.

 

 

 

edited for spelling

Edited January 11, 2006 by dor

[tomandsophie]

I assume that whatever is wired up in the boat is earthed to the hull. I will be plugging the genny into the boat's hookup point and running the washing machine from the 240v socket in the kitchen. So I guess that I should run an earth lead from the genny to a point on the hull (I guess a mooring dolly would do for ease of access.

[DHutch]

I assume that whatever is wired up in the boat is earthed to the hull. I will be plugging the genny into the boat's hookup point and running the washing machine from the 240v socket in the kitchen. So I guess that I should run an earth lead from the genny to a point on the hull.

Thats what we rely on with out little honda 1kw genny.

- The earth pin of the shoreline socket is earthed to the hull, which is siting in the canal.

- Then the generator is earthed to that pin by the lead between it and the boat.

 

 

Daniel

[tomandsophie]

Thats what we rely on with out little honda 1kw genny.

- The earth pin of the shoreline socket is earthed to the hull, which is siting in the canal.

- Then the generator is earthed to that pin by the lead between it and the boat.

Daniel

 

Daniel, I think you're right there - the earth of our shoreline must be connected to the boat, and the generator is connected to that so it should be earthed. I guess you are supposed to add an earth lead to the genny if you are connecting it directly to the appliance. Seeing as we are connecting it to our shoreline hookup socket the genny will be earthed through that.

Ah yes, I can see it all clearly now!

[Richard Bustens]

Why if you have a shore line do you want a gen set running?.

 

is the supply to small for the washer?

 

Now what concerns me is the fact that you seem to be mixing two seporate supplies onto the boat at the same time and if you want or need to use the gen set you should remove the land line thus removing the earth or at least put it through a switch so as one can be isolated from the other or there will be a chance of mixing them up together,