From Steve Rust:
..."The best option, although difficult to do, is to not use your engine as the main ground. You would use a grounding plate instead and an alternator and engine sensors that do not rely on the engine block for grounding."
As Steve suggested, I like to use discretely grounded (two wire) equipment
whenever possible. It's not that difficult - just requires an Isolated Alternator (such as Balmar
offers) and two-wire Instrument Senders (also isolated); and (of course) running dedicated Ground Wires from each of these devices to the Ground Bus.
..." By the way, some suggest that your saildrives will suffer if your anchor chain remains in contact with your windlass. It will cause a galvanic reaction through the grounding, causing your saildrives to lose paint, anodes, electrons."
As long as the Anchor Windlass is Bonded, there should not be any Galvanic problem with deployed chain. All significant metals (and certainly all Immersed
metals) should be Bonded.
GROUNDING vs GROUNDED
There are four main functions accomplished (on a boat) through GROUNDING
- prevent shock hazzard (AC green gnd wire)
2. Bonding - Interconnection of various items, often to prevent corrosion
(tie all immersed metals together)
& Static Amelioration - provide a preferred path to ground for lightning
- provide an RF ground, or zero reference for electronics
None of these (4) GroundING
wires are current-carrying, under NORMAL circumstances.
All of these Safety
or Bonding ground cables
are connected directly to the Main Ground Bus.
There are two main GROUNDED
5. AC Neutral (White)
6. DC Negative Return (Yellow or Black)
Both the AC Neutral and the DC (negative) Return are ultimately connected to ground (hence groundED
) , but are NOT GroundING wires.
The AC Neutral is connected to the (optional) Galvanic Isolator
thence to the AC Neutral bus (at AC Panel), and finally the Main Ground Bus.,
The DC Negative Return is connected to the DC Negative Bus (at DC Panel), thence the Battery
Negative Post, and finally to the Main Ground Bus.
The Main Ground Bus may be the Engine Block, or (preferably) a dedicated grounding terminal (bus, plate, or block) which is connected to an external ground plate.
To prevent confusion, it is preferred to refer to groundED
(current-carrying) conductors (numbers 5 & 6) by the term(s): AC “Neutral”, or DC “Negative” (return), and to the groundING cables
as “Safety” or “Bonding” ground.
See ABYC Section(s):
E-8 Alternating Current
E-9 Direct Current
(DC) Systems (Figures 15, 16 etc)
E-4 Lightning Protection