Mains electric earthing to battery negative???

nigelmercier said:
Really?
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I am afraid so, I have no other way of judging. I can read the instructions, work out what is happening sufficiently to be aware of what the installer is doing, but not the why. I just thought it was worthy to comment on the claim you made based on instructions in the box.
 
VicS said:
BS EN ISO 13297:2012
Unfortunately it costs quite a bit to buy so those in the trade who have bought copies are keeping its contents to themselves.​
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Nothing to do with the cost, which is not much anyway for BSI members but about respecting copyright, particularly on a public forum, however I don't feel it an infringement to say that your assumption about the concession in the obsolete version is well founded.​
 
If on a glass fibre boat a fault occurs on the AC circuit I don't see how my body will be a conductor to earth unless I am touching the engine or a sea cock, which are the only exposed metal objects connecting to sea water. The rest of the boat and the pontoon being wooden is an insulator!

Is this reasoning flawed ?
 
Mel said:
If on a glass fibre boat a fault occurs on the AC circuit I don't see how my body will be a conductor to earth unless I am touching the engine or a sea cock, which are the only exposed metal objects connecting to sea water. The rest of the boat and the pontoon being wooden is an insulator!

Is this reasoning flawed ?
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Why a seacock unless you are already a conductor
 
All my seacocks are in contact with the sea where an earth is (I think the sea is possibly at earth potential )!
My case was about me touching a source of AC at a fault point and conducting the AC power through my body, but then needing to connect to earth to complete a circuit that could cause harm !

The connection of mains earth to the engine/battery neg. and in my case seacocks that are all bonded together in a circuit to the anode would trigger the RCD on-board the boat, but the only case that it would protect me is when I am touching this bonded circuit - as all other aprts are insulated by glass fibre/wood and I would not be in harms way !!
 
Mel said:
All my seacocks are in contact with the sea where an earth is (I think the sea is possibly at earth potential )!
My case was about me touching a source of AC at a fault point and conducting the AC power through my body, but then needing to connect to earth to complete a circuit that could cause harm !

The connection of mains earth to the engine/battery neg. and in my case seacocks that are all bonded together in a circuit to the anode would trigger the RCD on-board the boat, but the only case that it would protect me is when I am touching this bonded circuit - as all other aprts are insulated by glass fibre/wood and I would not be in harms way !!
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Seacock my man should NOT be bonded, that was my reason for asking
 
As far as I can see there is no harm in connecting all seacocks. It should be considered that the engine cooling water seacock may be connected by a plastic hose but the water itself is a conductor !
 
Mel said:
As far as I can see there is no harm in connecting all seacocks. It should be considered that the engine cooling water seacock may be connected by a plastic hose but the water itself is a conductor !
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Modern thinking (I managed to avoid writing 'current thinking') is that bonding fittings is counter-productive. Assuming they are corrosion resistant, DZR or bronze, then they have no need of further protection on a grp boat. Bonding them can cause the less noble ones to corrode at the expense of the more noble ones, always assuming they can 'see' each other. This is often a problem in other technologies, where minor changes in composition in otherwise corrosion resistant alloys can create galvanic couples, e.g. preferential weld corrosion in stainless steels. If one of the fittings is brass, not something better, it can corrode in short order.

Seawater is not all that good a conductor and cannot be considered to be like a copper wire. Electrons in seawater travel in straight lines and, even assuming they could pass the impeller in the seawater pump, will never reach an engine. What they most certainly will not do is travel along a yacht hull, then turn a right angle and enter a skin fitting.
 
Mel said:
As far as I can see there is no harm in connecting all seacocks. !
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Contributing factor to the near loss of the FV Random Harvest several years ago

Also almost certainly a contributing factor to a formite's boat sinking in its marina berth more recently.
 
Well, I note what is said but my boat has been bonded across all seacocks and the stern drive shaft bearing housing plus the engine for nearly 20 years now and no issues !
As for the electrons getting past the impeller - my Yanmar water pump is integral to the engine and the water is in contact with the pump housing prior to the impeller contact point.
 
Mel said:
Well, I note what is said but my boat has been bonded across all seacocks and the stern drive shaft bearing housing plus the engine for nearly 20 years now and no issues !
As for the electrons getting past the impeller - my Yanmar water pump is integral to the engine and the water is in contact with the pump housing prior to the impeller contact point.
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Ok Mel, your boat your choice.
mine are not bonded & no hull anode either, just a shaft anode but i have added a 50m/m disc anode to the P bracket.
 
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