Earth Bonding.

[j***@btopenworld.com]

Hi All,

Can anyone advise me on the size of earth cable to bond to the hull on
a narrowboat. The boat will be wired up for an 1800 watt inverter and
shoreline connection.

Many thanks,

John.

[Phil R]

Post by j***@btopenworld.com
Hi All,
Can anyone advise me on the size of earth cable to bond to the hull on
a narrowboat. The boat will be wired up for an 1800 watt inverter and
shoreline connection.

Three strand at least :-)))

[Phil R]

Post by Phil R

Post by j***@btopenworld.com
Hi All,
Can anyone advise me on the size of earth cable to bond to the

hull

Post by Phil R
on

Post by j***@btopenworld.com
a narrowboat. The boat will be wired up for an 1800 watt inverter

and

Post by j***@btopenworld.com
shoreline connection.

Three strand at least :-)))

Sorry
Please don't take my post seriously. It was only a rather poor
response to your post appearing on my newsreader three times!

I am sure one of the electrical experts will be here within the next
24 hours to give a proper reply.

Cheers
Phil

[Ron Jones]

Post by Phil R

Post by Phil R

Post by j***@btopenworld.com
Hi All,
Can anyone advise me on the size of earth cable to bond to the hull
on a narrowboat. The boat will be wired up for an 1800 watt
inverter and shoreline connection.

Three strand at least :-)))

Sorry
Please don't take my post seriously. It was only a rather poor
response to your post appearing on my newsreader three times!
I am sure one of the electrical experts will be here within the next
24 hours to give a proper reply.

Don't forget the galvanic isolator!

[Electricky Dicky]

Post by Ron Jones

Post by Phil R

Post by Phil R

Post by j***@btopenworld.com
Hi All,
Can anyone advise me on the size of earth cable to bond to the hull
on a narrowboat. The boat will be wired up for an 1800 watt
inverter and shoreline connection.

Three strand at least :-)))

Sorry
Please don't take my post seriously. It was only a rather poor
response to your post appearing on my newsreader three times!
I am sure one of the electrical experts will be here within the next
24 hours to give a proper reply.

Don't forget the galvanic isolator!

Sensible advice!

Post by Ron Jones
--

Shoreline earth to one side of galvanic Isolator, other side of GI to
AC consumer unit earth bar. All boat remaining AC earth wires to this
bar.
AC consumer unit earth bar to hull with 4mm or 6mm earth wire. 2.5mm
is acceptable to match shoreline if the run is short. I suggest 4 or
6mm for mechanical strength only.

DC -ve bond to hull anything from 16mm2 upwards. Isolate DC -ve from
hull with busbar or post, then run seperate single bond. It is
sensible to have AC and DC bond points near to each other say within
600mm.

Ensure that paint is scraped away at bond points, best option is an
8mm or 6mm stud (preferably brass with brass nuts) tapped to bulkhead,
or other hull steel (preferably nor base or hull sides!) Nut down
tight. Earth cable nutted to that. Protect bare steel with paint or
conformal coating after connecting wire.
Both earth bond points should be easily accessible to allow
examination and disconnection for system test.
Depends on the inverter what you do about E-N link to allow RCD to
trip from inverter supply. Ensure that this link cannot interfere with
E - N from shoreline.

Remember that the RCD test button ONLY tests the RCD not the system!

Remember YELLOW crimps are for 4 or 6mm wire. They are not for
universal use on any size wire! (Rant over)
All crimping with a PROPER crimper, not pliers (2nd rant over)
If a stud is xmm diameter then use an xmm diameter crimp not one x+n
mm diameter bigger! (3rd rant over)

Richard

Nb "Pound Eater" Parkend G+S

[Guava]

Phill R,
This was my first posting and I have changed the display name to
'Guava', my N.B. Many thanks for your comprehensive answer it is much
appreciated.

Appologies to all for the posting to be listed '3' times, I have no
idea why that happened.

John.

Post by Electricky Dicky

Post by Ron Jones

Post by Phil R

Post by Phil R

Post by j***@btopenworld.com
Hi All,
Can anyone advise me on the size of earth cable to bond to the hull
on a narrowboat. The boat will be wired up for an 1800 watt
inverter and shoreline connection.

Three strand at least :-)))

Sorry
Please don't take my post seriously. It was only a rather poor
response to your post appearing on my newsreader three times!
I am sure one of the electrical experts will be here within the next
24 hours to give a proper reply.

Don't forget the galvanic isolator!

Sensible advice!

Post by Ron Jones
--

Shoreline earth to one side of galvanic Isolator, other side of GI to
AC consumer unit earth bar. All boat remaining AC earth wires to this
bar.
AC consumer unit earth bar to hull with 4mm or 6mm earth wire. 2.5mm
is acceptable to match shoreline if the run is short. I suggest 4 or
6mm for mechanical strength only.
DC -ve bond to hull anything from 16mm2 upwards. Isolate DC -ve from
hull with busbar or post, then run seperate single bond. It is
sensible to have AC and DC bond points near to each other say within
600mm.
Ensure that paint is scraped away at bond points, best option is an
8mm or 6mm stud (preferably brass with brass nuts) tapped to bulkhead,
or other hull steel (preferably nor base or hull sides!) Nut down
tight. Earth cable nutted to that. Protect bare steel with paint or
conformal coating after connecting wire.
Both earth bond points should be easily accessible to allow
examination and disconnection for system test.
Depends on the inverter what you do about E-N link to allow RCD to
trip from inverter supply. Ensure that this link cannot interfere with
E - N from shoreline.
Remember that the RCD test button ONLY tests the RCD not the system!
Remember YELLOW crimps are for 4 or 6mm wire. They are not for
universal use on any size wire! (Rant over)
All crimping with a PROPER crimper, not pliers (2nd rant over)
If a stud is xmm diameter then use an xmm diameter crimp not one x+n
mm diameter bigger! (3rd rant over)
Richard
Nb "Pound Eater" Parkend G+S

[Guava]

Many thanks Richard for your help and advice, it is greatly
appreciated.

john.

[Paul Scott]

Post by Electricky Dicky
Depends on the inverter what you do about E-N link to allow RCD to
trip from inverter supply. Ensure that this link cannot interfere with
E - N from shoreline.
Richard

Does anyone know why so many (budget priced?) inverters do not have this
link made internally? Surely standard certification should require it?

Paul

[Prepair Ltd]

On Mon, 12 Dec 2005 12:58:53 +0000 (UTC), "Paul Scott"

Post by Paul Scott

Post by Electricky Dicky
Depends on the inverter what you do about E-N link to allow RCD to
trip from inverter supply. Ensure that this link cannot interfere with
E - N from shoreline.
Richard

Does anyone know why so many (budget priced?) inverters do not have this
link made internally? Surely standard certification should require it?
Paul

Probably because it may cause problems (earth loops or false RCD
tripping) if used in a house rather than a boat? Most buildings have
PME connection where the neutral is bonded at the point of cable entry
to the building.

Peter
--
Peter A Forbes
Prepair Ltd, Luton, UK
***@easynet.co.uk
http://www.prepair.co.uk

[brianH]

Post by Paul Scott

Post by Electricky Dicky
Depends on the inverter what you do about E-N link to allow RCD to
trip from inverter supply. Ensure that this link cannot interfere with
E - N from shoreline.
Richard

Does anyone know why so many (budget priced?) inverters do not have this
link made internally? Surely standard certification should require it?

Is a Mastervolt true sinewave 1500 watt inverter a budget priced one?

[Electricky Dicky]

On Mon, 12 Dec 2005 12:58:53 +0000 (UTC), "Paul Scott"

Post by Paul Scott

Post by Electricky Dicky
Depends on the inverter what you do about E-N link to allow RCD to
trip from inverter supply. Ensure that this link cannot interfere with
E - N from shoreline.
Richard

Does anyone know why so many (budget priced?) inverters do not have this
link made internally? Surely standard certification should require it?
Paul

I have always wodered about this. When I asked them wot knows, the
answer was that different countries different regs, typically
Australia is a big market and AIUI link not required there. Uk market
is apparently small compared to some.

Richard

Nb "Pound Eater" Parkend G+S

[Graham Brooker]

Post by Ron Jones
Don't forget the galvanic isolator!

I would not risk grounding/earthing my boat even with a galvanic isolator as
it may prove unreliable when the diodes start leaking. I spent the extra
money and bought a Victron isolating transformer and removed the shoreline
earth bond altogether. Providing a local "earth" bond is simply a matter
of following the instructions with the unit to ensure the RCDs can trip if
needed - just bond one side of the secondary direct to the hull before the
RCDs. No earth/ground connection so no risk of galvanic corrosion -
everything safe from all other aspects. There may be cheaper alternatives
on the market but the Victron spec outweighed anything available 3 years
ago.

Graham Brooker

[Ron Jones]

Post by Graham Brooker

Post by Ron Jones
Don't forget the galvanic isolator!

I would not risk grounding/earthing my boat even with a galvanic
isolator as it may prove unreliable when the diodes start leaking. I
spent the extra money and bought a Victron isolating transformer and
removed the shoreline earth bond altogether. Providing a local
"earth" bond is simply a matter of following the instructions with
the unit to ensure the RCDs can trip if needed - just bond one side
of the secondary direct to the hull before the RCDs. No earth/ground
connection so no risk of galvanic corrosion - everything safe from
all other aspects. There may be cheaper alternatives on the market
but the Victron spec outweighed anything available 3 years ago.
Graham Brooker

I like your style. I've seen boats with isolators that need bottoms
blacking more often than usual - due to shoreline being attached. As we
don't live on the boat, I've gone the other way, and only use 12V stuff.

[Steve Blinkhorn]

Ron Jones <***@ronjones.org.uk> wrote:

: I like your style. I've seen boats with isolators that need bottoms
: blacking more often than usual - due to shoreline being attached. As we
: don't live on the boat, I've gone the other way, and only use 12V stuff.

Not to contradict anything that's been said about how galvanic
corrosion can occur, my experience has been otherwise.

Baud Maud has been connected to shore power at Napton Marina for 9
years, with no form of isolator. Because of my health problems, she
has been rather neglected for much of that time, and we had her hauled
out for the first time in July. The anodes had clearly been doing
their job, but there was still a significant amount of metal, and I
would have guessed that they would have lasted another year or two.
Because of the way they do these things at Calcutt, I was able to
examine the baseplate from underneath as well as the rest of the hull,
and I could see no sign at all of pitting or corrosion. Just an
awful lot of mussels.

I suppose it is possible that because she is such a very electric boat
the earthing arrangements may by chance rather than design be somehow
optimal: if so, I would like to work out how for the benefit of
everyone else. I have to say I was pleasantly surprised.

[Ron Jones]

Post by Steve Blinkhorn

Post by Ron Jones
I like your style. I've seen boats with isolators that need bottoms
blacking more often than usual - due to shoreline being attached.
As we don't live on the boat, I've gone the other way, and only use
12V stuff.

Not to contradict anything that's been said about how galvanic
corrosion can occur, my experience has been otherwise.
Baud Maud has been connected to shore power at Napton Marina for 9
years, with no form of isolator. Because of my health problems, she
has been rather neglected for much of that time, and we had her hauled
out for the first time in July. The anodes had clearly been doing
their job, but there was still a significant amount of metal, and I
would have guessed that they would have lasted another year or two.
Because of the way they do these things at Calcutt, I was able to
examine the baseplate from underneath as well as the rest of the hull,
and I could see no sign at all of pitting or corrosion. Just an
awful lot of mussels.
I suppose it is possible that because she is such a very electric boat
the earthing arrangements may by chance rather than design be somehow
optimal: if so, I would like to work out how for the benefit of
everyone else. I have to say I was pleasantly surprised.

There are many factors which can affect the rate of electrolytic corrosion
(to give it its proper name)...
Some are
1. Water quality, the higher the quality, the lower the current flow.
2. Amount of paint
3. Amount and size of anodes (these will go first!)
4. Site earthing material (copper?)
5. Quality of steel
6. Other boats also bonded to earth on the same earth rod (they may get
eaten first)

Certainly a Fe-Cu couple will give you 0.805 volts in an ideal environment,
with the iron dissolving...

[Peter]

I personally wouldn't bother about galvanic isolators unless the power is
being left on continuously.
As to the earth connection, the normal heavy duty earth cable used for
domestic earthing to the earth spike should be fine.

[Ron Jones]

Post by Peter
I personally wouldn't bother about galvanic isolators unless the
power is being left on continuously.
As to the earth connection, the normal heavy duty earth cable used for
domestic earthing to the earth spike should be fine.

We'll watch your boat sink first then...
The galvanic isolator has nothing to do with the power on or off. It's to
protect the hull from becoming a battery electrode vs. the grounding rod
[steel boat to copper ground rod with an electolyte (canal water) =
battery - with the steel being eaten away.] I've even seen piling been
eaten away - where the boat has rested against the piling, so the
boat+piling has become the overall electrode.

[Paul Scott]

Post by Peter
As to the earth connection, the normal heavy duty earth cable used for
domestic earthing to the earth spike should be fine.

If you mean the fixed cable used in a house it won't be fine, it hasn't the
flexibility, ie number of strands, required for use on a boat, and would
fail a BSS examination.

Paul