DC system bonding

[Sir Nibble]

I frankly doubt that you will eradicate all trace of earth leakage. If you look for it with a sensitive meter then it will arise as soon as the air gets a little moist.

[Gibbo]

I frankly doubt that you will eradicate all trace of earth leakage. If you look for it with a sensitive meter then it will arise as soon as the air gets a little moist.

 

Agrred. There's always going to be some leakage in a damp environment. I'm trying to get a grip on what should be considered an acceptable leak.

 

Gibbo

[Sir Nibble]

I have seen many salty water boats with test switches connected to two lamps. You start the engine at the beginning of the day and press the button, if a lamp lights it indicates a fault and it's polarity. I appreciate that far smaller currents than what is needed to light a lamp may be considered significant to electrolysis but I wouldn't personally much fancy trying to track down a leak that small, especially as it may well represent the sum of several tiny leaks, or one leak with a 3metre interface with the hull metalwork. It is also possible of course that tiny leaks may simply be impossible to eradicate without a totally disproportionate expenditure in time and money.

KISS, bond the hull to -ve and the problem will not arise, maybe stick a fuse in the -ve to hull with a warning lamp across it.

[Gibbo]

KISS, bond the hull to -ve and the problem will not arise, maybe stick a fuse in the -ve to hull with a warning lamp across it.

 

That's my opinion too. It's foolproof.

 

Unfortunately some plumbers don't agree.

 

Gibbo

[chris w]

That's my opinion too. It's foolproof.

 

Unfortunately some plumbers don't agree.

 

Gibbo

Shhhhhhhhhhhhh... you'll awaken the tw@t again

[blackrose]

Just seen this thread.

 

Am I correct in thinking that if the DC system is bonded to the hull then any stray current indicator is unnecessary?

 

Also without wishing to go off topic or start another argument, what is the purported advantage of not bonding the DC system to the hull?

Edited November 19, 2008 by blackrose

[Gibbo]

Am I correct in thinking that if the DC system is bonded to the hull then any stray current indicator is unnecessary?

 

Yes, you are correct.

 

Also without wishing to go off topic or start another argument, what is the purported the advantage of not bonding the DC system to the hull?

 

Intuition seems to tell some people that bonding the DC system to the hull increases hull corrosion. It is incorrect and it's only after actually thinking about it clearly and drawing diagrams does this become apparent. But it is a gut feeling to many that bonding the hull can cause corrosion problems. Even though it's wrong.

 

Bonding the positive to the hull is lethal for stray current corrosion and should NEVER be done (that's why they stopped making positive grounded cars). If the negative is bonded it CANNOT cause stray current erosion of the hull.

 

Some poeple also quote the idea that an isolated system is safer because if tools that are being used to work on the electrical system contact the hull there is no spark. I struggle to get my head round the logic behind this argument.

 

Gibbo

[blackrose]

Yes, you are correct.

 

 

 

Intuition seems to tell some people that bonding the DC system to the hull increases hull corrosion. It is incorrect and it's only after actually thinking about it clearly and drawing diagrams does this become apparent. But it is a gut feeling to many that bonding the hull can cause corrosion problems. Even though it's wrong.

 

Bonding the positive to the hull is lethal for stray current corrosion and should NEVER be done (that's why they stopped making positive grounded cars). If the negative is bonded it CANNOT cause stray current erosion of the hull.

 

Some poeple also quote the idea that an isolated system is safer because if tools that are being used to work on the electrical system contact the hull there is no spark. I struggle to get my head round the logic behind this argument.

 

Gibbo

 

Thank you

[Amicus]

This geezer Intuition has got a lot to answer for.

[Keeping Up]

This geezer Intuition has got a lot to answer for.

Inn-tuition, isn't that what some geezer tells you in the pub?

[chris w]

Inn-tuition, isn't that what some geezer tells you in the pub?

Inuit_ion - must have been Eskimo logic

[Sir Nibble]

Some poeple also quote the idea that an isolated system is safer because if tools that are being used to work on the electrical system contact the hull there is no spark. I struggle to get my head round the logic behind this argument.

 

Gibbo

So disconnect the earthed pole of the battery first like you're s'posed to. If the system must be live, for fault finding purposes perhaps, disconnect the battery and insert a small jump lead with a fuseholder in to re-establish the supply. If there are people who would really insist on an insulated system in order to prevent them creating an accidental short then perhaps they should have the tools taken away and be told to sit quietly whilst the nice man mends the boat.

[Denis R]

If there are people who would really insist on an insulated system in order to prevent them creating an accidental short then perhaps they should have the tools taken away and be told to sit quietly whilst the nice man mends the boat.

[Gibbo]

If there are people who would really insist on an insulated system in order to prevent them creating an accidental short then perhaps they should have the tools taken away and be told to sit quietly whilst the nice man mends the boat.

 

It's usually plumbers who recommend an insulated system

 

Gibbo

[Sir Nibble]

It's usually plumbers who recommend an insulated system

 

Gibbo

I fail to understand why, do they want the mains earth/neutral bond removed as well?

[Gibbo]

I fail to understand why, do they want the mains earth/neutral bond removed as well?

 

I didn't really make that clear. It was just one plumber in particular.

 

I think it's a stupid idea and a bonded system is far better.

 

Gibbo