Join Date: Dec 2002
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DC Ground vs. Negative Return
GROUNDING vs GROUNDED:
There are four main functions accomplished (on a boat) through GROUNDING:
1. Safety - prevent shock hazzard (AC green gnd wire)
2. Bonding - prevent corrosion (tie all immersed metals together)
3. Lightning Amelioration - provide a preferred path to gnd for lightning.
4. Counterpoise - provide an RF gnd, or zero reference for electronbics.
None of these (4) GroundING wires are current-carrying, under NORMAL circumstances.
There are two main GROUNDED current-carrying conductors:
5. AC Neutral (White)
6. DC Return (Yellow or Black)
Both the AC Neutral and the DC (negative) Return are connected to ground (hence grounded) , but are NOT Grounding wires.
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).
See ABYC Section(s):
E-8 Alternating Current (AC) Systems
E-9 Direct Current (DC) Systems (Figures 15, 16 etc)
E-4 Lightning Protection
Hope the helps,