Earthing 'mains' circuit on my boat

[pcatterall]

There was some mention about this on a recent thread. Our old Neptunian has a mains circuit but I have not seen an earth connection anywhere. I note that my camper van has its own 'mains' circuit and, of course there is no connection to earth there.
What is the situation on boats as against camper vans?

 

[lustyd]

I did some reading on this for my old boat and there was no one good answer, it was very much a "who would you prefer to kill" kind of outcome. In some scenarios you want to earth on the boat and some back up to the shore supply, but there's always a compromise somewhere. I'm sure there's a current standard available which would remove the need to choose

 

[RupertW]

I did some reading on this for my old boat and there was no one good answer, it was very much a "who would you prefer to kill" kind of outcome. In some scenarios you want to earth on the boat and some back up to the shore supply, but there's always a compromise somewhere. I'm sure there's a current standard available which would remove the need to choose

We Earth both as recommended with a Galvanic isolator.

 

[lustyd]

We Earth both as recommended with a Galvanic isolator.

I seem to recall there are situations where that could kill a person in the water due to the way some marina supplies are set up. It was 10 years ago now, but I distinctly recall there being danger to someone in every scenario!

 

[dankilb]

I’m pretty sure our system isn’t earthed to the boat (12v ground etc.) only the marina supply - but now understand from the recent (inverter!) threads that this is something to look at too...

 

[RupertW]

I seem to recall there are situations where that could kill a person in the water due to the way some marina supplies are set up. It was 10 years ago now, but I distinctly recall there being danger to someone in every scenario!

The marina side of the AC is earthed back to the marina, the boat side is earthed to the water (along with neutral) with the GI separating them.That should be safe if the marina is earthed properly - if it’s not then all bets are off.

 

[lustyd]

It's going back 10 years since I read it but I think the issue was that some marinas earth to water on the pontoon so you can create a circuit via the water. I'd have to dig out the book to find the detail

 

[lustyd]

To be clear I'm not saying don't do it, it probably is the best option.

 

[Jabs]

Be very careful here. In UK power supplies are usually rigged so that the earth is at ground potential. This does not follow in all countries as I found to my cost when my saildrive became gouda.

The best solution is an isolating transformer to ensure that nothing 'off' the boat affects anything on the boat.

Consider a neighbour with a ground fault raises the earth potential to, say 20 volts! In my case the ground was at 70 volts! The leg was fizzing!

Tony

 

[PaulRainbow]

Shore Power

Years ago the incoming Protective Earth only went to the onboard systems, it was not connected to "the water", so there was no connection between your underwater gear and the marina/surrounding boats, no need for a GI.

For some time now it has been a requirement that the PE is connected to "the water" (to the hull of a metal boat, grounding plate (if fitted) or an anode etc). This does create the aforementioned path to other boats etc, so a GI or isolation transformer should be fitted (although neither is an actual regulatory requirement). The GI should be fitted between the incoming socket and the consumer unit. It's best to have a decent GI that can be tested or warn you of faults. It is also a regulatory requirement that a GI shall fail safe, that means closed circuit, so you still have a PE, but you obviously lose the galvanic protection, hence the need for testing or a warning system.

There are no regulatory requirements that force retrofitting to boats built prior to it becoming a requirement or for anyone fitting a shore power system on a boat that has previously not had one, the regulations only apply to new builds. It would, however, be a sensible move to comply if you are making changes, at the very least. Although not required to do so, i always carry out shore power installations in accordance with the latest regulations.

Inverters and Generators

There has been lots said about such installations on here recently, with a great deal of misunderstanding and very poor/lethally dangerous advice being given.

Fixed installations

This means permanently fitted to the boat, connected to onboard systems via the vessels consumer unit etc. The neutral and Earth must be bonded at source., if you can't bond them, you can't fit it. Each supply (shore power, inverter, generator) should be connected to a change over device (switch, switches, relays etc), these must be break before make and designed so that it is impossible to have two sources connected at the same time.

I read of people fitting a generator or inverter and plugging it into the boats shore power inlet. This can be acceptable, but the neutral and Earth must still be bonded. If it can't be bonded, again, do not plug it into the boat.

I also read of people bonding the neutral and earth in the cable that connects the device to the boat. This is, IMO, undesirable. You must be absolutely certain that you use this cable for connecting to the boat and you must be absolutely certain that you don't use the cable for anything else, too much room for error here, don't do it.

The PE earth of the device must be connected to "the water" (to the hull of a metal boat, grounding plate (if fitted) or an anode etc). All PE connections should be made to the same point on the boat. There is no point connecting these PE connections through a GI, it's pointless and only introduces points of failure that could be avoided by not doing so.

Portable "Installations"

If you cannot comply with the fixed installation requirements, you're left with a portable arrangement. You must not connect this to the vessels systems directly. You should only plug suitably fused equipment into the devices sockets, or a sensible extension lead, plugged into the devices socket. A socket or two, fitted to the vessel and only connected via a cable to the portable device might be acceptable, as it's basically the same as an extension lead. If the device has an Earth point on the case, connect this to the vessel the same as you would with a fixed installation.

With these installations you are obviously reliant on the internal protection of the device itself. The quality of portable inverters varies enormously, some are pretty good, others are positively lethal if a fault occurs. Manufacturers fitting instructions and advice should obviously be adhered to.

It's worth remembering, an AC supply from a £200 Chinese Ebay inverter can kill you, your friends and your family, just as well as the supply in your house.

Just a brief comment regarding swimmers in the water. The requirement for connecting the PE to the water does not increase the risk to swimmers, it reduces it. Tiny AC currents in the water can paralyse a swimmer, leading to drowning. A proper AC installation, with the PE of all equipment grounded to the water means you onboard safety equipment will protect those swimmers, this is largely why the regulation was brought in. Google "electric shock drowning" plenty to read online, rather than me repeat it. It's much worse in fresh water than in salt water.

 

[jwfrary]

Shore Power

Years ago the incoming Protective Earth only went to the onboard systems, it was not connected to "the water", so there was no connection between your underwater gear and the marina/surrounding boats, no need for a GI.

For some time now it has been a requirement that the PE is connected to "the water" (to the hull of a metal boat, grounding plate (if fitted) or an anode etc). This does create the aforementioned path to other boats etc, so a GI or isolation transformer should be fitted (although neither is an actual regulatory requirement). The GI should be fitted between the incoming socket and the consumer unit. It's best to have a decent GI that can be tested or warn you of faults. It is also a regulatory requirement that a GI shall fail safe, that means closed circuit, so you still have a PE, but you obviously lose the galvanic protection, hence the test for testing or a warning system.

There are no regulatory requirements that force retrofitting to boats built prior to it becoming a requirement or for anyone fitting a shore power system on a boat that has previously not had one, the regulations only apply to new builds. It would, however, be a sensible move to comply if you are making changes, at the very least. Although not required to do so, i always carry out shore power installations in accordance with the latest regulations.

Inverters and Generators

There has been lots said about such installations on here recently, with a great deal of misunderstanding and very poor/lethally dangerous advice being given.

Fixed installations

This means permanently fitted to the boat, connected to onboard systems via the vessels consumer unit etc. The neutral and Earth must be bonded at source., if you can't bond them, you can't fit it. Each supply (shore power, inverter, generator) should be connected to a change over device (switch, switches, relays etc), these must be break before make and designed so that it is impossible to have two sources connected at the same time.

I read of people fitting a generator or inverter and plugging it into the boats shore power inlet. This can be acceptable, but the neutral and Earth must still be bonded. If it can't be bonded, again, do not plug it into the boat.

I also read of people bonding the neutral and earth in the cable that connects the device to the boat. This is, IMO, undesirable. You must be absolutely certain that you use this cable for connecting to the boat and you must be absolutely certain that you don't use the cable for anything else, too much room for error here, don't do it.

The PE earth of the device must be connected to "the water" (to the hull of a metal boat, grounding plate (if fitted) or an anode etc). All PE connections should be made to the same point on the boat. There is no point connecting these PE connections through a GI, it's pointless and only introduces points of failure that could be avoided by not doing so.

Portable "Installations"

If you cannot comply with the fixed installation requirements, you're left with a portable arrangement. You must not connect this to the vessels systems directly. You should only plug suitably fused equipment into the devices sockets, or a sensible extension lead, plugged into the devices socket. A socket or two, fitted to the vessel and only connected via a cable to the portable device might be acceptable, as it's basically the same as an extension lead. If the device has an Earth point on the case, connect this to the vessel the same as you would with a fixed installation.

With these installations you are obviously reliant on the internal protection of the device itself. The quality of portable inverters varies enormously, some are pretty good, others are positively lethal if a fault occurs. Manufacturers fitting instructions and advice should obviously be adhered to.

It's worth remembering, an AC supply from a £200 Chinese Ebay inverter can kill you, your friends and your family, just as well as the supply in your house.

Just a brief comment regarding swimmers in the water. The requirement for connecting the PE to the water does not increase the risk to swimmers, it reduces it. Tiny AC currents in the water can paralyse a swimmer, leading to drowning. A proper AC installation, with the PE of all equipment grounded to the water means you onboard safety equipment will protect those swimmers, this is largely why the regulation was brought in. Google "electric shock drowning" plenty to read online, rather than me repeat it. It's much worse in fresh water than in salt water.

Excellent comprehensive, and should be stickied in my opinion.

 

[Spirit (of Glenans)]

Shore Power

Years ago the incoming Protective Earth only went to the onboard systems, it was not connected to "the water", so there was no connection between your underwater gear and the marina/surrounding boats, no need for a GI.

For some time now it has been a requirement that the PE is connected to "the water" (to the hull of a metal boat, grounding plate (if fitted) or an anode etc). This does create the aforementioned path to other boats etc, so a GI or isolation transformer should be fitted (although neither is an actual regulatory requirement). The GI should be fitted between the incoming socket and the consumer unit. It's best to have a decent GI that can be tested or warn you of faults. It is also a regulatory requirement that a GI shall fail safe, that means closed circuit, so you still have a PE, but you obviously lose the galvanic protection, hence the need for testing or a warning system.

There are no regulatory requirements that force retrofitting to boats built prior to it becoming a requirement or for anyone fitting a shore power system on a boat that has previously not had one, the regulations only apply to new builds. It would, however, be a sensible move to comply if you are making changes, at the very least. Although not required to do so, i always carry out shore power installations in accordance with the latest regulations.

Inverters and Generators

There has been lots said about such installations on here recently, with a great deal of misunderstanding and very poor/lethally dangerous advice being given.

Fixed installations

This means permanently fitted to the boat, connected to onboard systems via the vessels consumer unit etc. The neutral and Earth must be bonded at source., if you can't bond them, you can't fit it. Each supply (shore power, inverter, generator) should be connected to a change over device (switch, switches, relays etc), these must be break before make and designed so that it is impossible to have two sources connected at the same time.

I read of people fitting a generator or inverter and plugging it into the boats shore power inlet. This can be acceptable, but the neutral and Earth must still be bonded. If it can't be bonded, again, do not plug it into the boat.

I also read of people bonding the neutral and earth in the cable that connects the device to the boat. This is, IMO, undesirable. You must be absolutely certain that you use this cable for connecting to the boat and you must be absolutely certain that you don't use the cable for anything else, too much room for error here, don't do it.

The PE earth of the device must be connected to "the water" (to the hull of a metal boat, grounding plate (if fitted) or an anode etc). All PE connections should be made to the same point on the boat. There is no point connecting these PE connections through a GI, it's pointless and only introduces points of failure that could be avoided by not doing so.

Portable "Installations"

If you cannot comply with the fixed installation requirements, you're left with a portable arrangement. You must not connect this to the vessels systems directly. You should only plug suitably fused equipment into the devices sockets, or a sensible extension lead, plugged into the devices socket. A socket or two, fitted to the vessel and only connected via a cable to the portable device might be acceptable, as it's basically the same as an extension lead. If the device has an Earth point on the case, connect this to the vessel the same as you would with a fixed installation.

With these installations you are obviously reliant on the internal protection of the device itself. The quality of portable inverters varies enormously, some are pretty good, others are positively lethal if a fault occurs. Manufacturers fitting instructions and advice should obviously be adhered to.

It's worth remembering, an AC supply from a £200 Chinese Ebay inverter can kill you, your friends and your family, just as well as the supply in your house.

Just a brief comment regarding swimmers in the water. The requirement for connecting the PE to the water does not increase the risk to swimmers, it reduces it. Tiny AC currents in the water can paralyse a swimmer, leading to drowning. A proper AC installation, with the PE of all equipment grounded to the water means you onboard safety equipment will protect those swimmers, this is largely why the regulation was brought in. Google "electric shock drowning" plenty to read online, rather than me repeat it. It's much worse in fresh water than in salt water.

I didn't think marinas allowed swimming within their environs , although falling in could be considered involuntary swimming.

 

[lustyd]

Railways don't allow people on the lines either. Have you met other humans? You might be disapointed

 

[ithet]

Just a brief comment regarding swimmers in the water. The requirement for connecting the PE to the water does not increase the risk to swimmers, it reduces it. Tiny AC currents in the water can paralyse a swimmer, leading to drowning. A proper AC installation, with the PE of all equipment grounded to the water means you onboard safety equipment will protect those swimmers, this is largely why the regulation was brought in. Google "electric shock drowning" plenty to read online, rather than me repeat it. It's much worse in fresh water than in salt water.

(My highlighting)

That was what I understood from reading Nigel Calder (yes I know). I was initially worried about not having the earth bonding, but my take now is that it is less important in UK than say US or Southern Europe. It is not normal to swim in marinas in Britain! I cannot think of normal circumstances where I would be plugged in at a marina and anyone would be in the water. Of course to cover all circumstances then the bonding would be safest, but is not on my urgent to-do list especially as I am on a river mooring.

 

[pcatterall]

Thanks all. I will have to go through Pauls most useful explanation step by step to get it into my brain!
So what IS the difference between my campers earthing needs and a boats? Is it simply that you CAN earth your boats system but short of driving a rod into the ground you can earth a van?
If its not essential on a van then why on a boat?

 

[RupertW]

Thanks all. I will have to go through Pauls most useful explanation step by step to get it into my brain!
So what IS the difference between my campers earthing needs and a boats? Is it simply that you CAN earth your boats system but short of driving a rod into the ground you can earth a van?
If its not essential on a van then why on a boat?

How many people swim around a conductive medium around your van?

 

[lustyd]

I appologise to the OP, I seem to have somewhat diverted the thread. Hopefully Paul's info answers the question though so not too disruptive!

 

[PaulRainbow]

Thanks all. I will have to go through Pauls most useful explanation step by step to get it into my brain!
So what IS the difference between my campers earthing needs and a boats? Is it simply that you CAN earth your boats system but short of driving a rod into the ground you can earth a van?
If its not essential on a van then why on a boat?

Your van sits on rubber tyres so you can't (as you said) connect anything to Earth. If you connect the Earth from an inverter that has the neutral and earth bonded to the chassis of the van you create the possibility of touching live and neutral at the same time, which doesn't otherwise exist.

 

[PaulRainbow]

I didn't think marinas allowed swimming within their environs , although falling in could be considered involuntary swimming.

Ah, but i didn't say "swimmers in the marina", i said "swimmers in the water".

There is water outside of your marina

But seriously, as ithet pointed out, we don't tend to swim in our marinas, so it's not so common in the UK to be connected to shore power with swimmers in the water.

But other considerations are that inland waterway boats could have swimmers in the river, which is where the risk is greater (fresh water). It's also much more common in other parts of the World and the regs are pretty much global.

 

[superheat6k]

Ah, but i didn't say "swimmers in the marina", i said "swimmers in the water".

There is water outside of your marina

But seriously, as ithet pointed out, we don't tend to swim in our marinas, so it's not so common in the UK to be connected to shore power with swimmers in the water.

But other considerations are that inland waterway boats could have swimmers in the river, which is where the risk is greater (fresh water). It's also much more common in other parts of the World and the regs are pretty much global.

There is an important recent change in regard to marina swimming inasmuch as SUP users are now often also boatowners and as such use their boats in their marina berths as very convenient launch points. Falling in (a lot !) is part of the learning curve. And many river based marinas will have water bordering on fresh especially after heavy rainfall.

This is one of the reasons I routinely fish immersed shorepower cables out of the water if I see them, as well as to reduce stray higher voltage AC current corrosion, which ignores the niceties of a GI, and can destroy underwater metalwork in short order.