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Boats on hard ground so lets talk grounds

3K views 12 replies 9 participants last post by  patrickrea 
#1 ·
My boat has no ground wire for the 110V, the wiring diagram shows a 10 gauge black wire running from the ground buss bar in the panel to the engine block.
We all know that 12v DC grounds are black in cars and boats, but should the 110v AC ground be Black as the diagram shows (always default to the manufacturers instructions?) or Green?
 
#4 ·
anemoneii
I'm not really sure what Garffin is trying to say. Are you saying that all your onboard AC circuits are 3 wire but there is not a ground to the negative bus (or engine block)? If the answer is yes I would use green so it can be identified easily in the future. A black wire to the negative bus would look like it came from a DC source. Do you have or are you going to install a galvanic isolator?
 
#5 ·
MiTi has it right- Black is hot, white is neutral and green (or bare) is ground.

In household AC outlets, the bare copper wire goes to the green screw, black goes to the brass screw, and white to the silver screw. So remember this phrase when wiring up 110V 60Hz AC switches and receptacles: "Black to brass will save your ass, and ground is green as grass".

This is for shore power right?
 
#6 ·
This is right for shore power except that there is no ground on board. All grounds are wired to the panel and then connected to the ground on the dock. There should be no ground for the shore power hooked up to the engine block, keel bolts, dynaplate, or any other grounding point commonly used in the d.c. system.
 
#8 ·
You are making this conversation interesting, I have Don Casey's book, Sailboat Electrics Simplified, and he shows the ground hooked to the engine, also the wiring diagram for my boat shows one (although it is not there). The Engine is certainly grounded to the 12v DC system.
 
#10 · (Edited by Moderator)
The ground wire should be green as stated above. It should also be connected to both the ground pin on the AC adapter and the engine block. When doing this try to keep all grounded and bonded connections in a star pattern. This means a single wire from each device and engine to the main ground bus. Basically, you do not want to have one device/thru-hull in series with another device/thru-hull.
 
#11 ·
xsboats
Yes there should. Not only does ABYC call for an AC ground to the central ground on the engine block but it makes common sense. Invertors and chargers are a bridge between the AC and DC systems. If an AC item shorts or a case becomes energized the current has to have somewhere to go. All AC circuits should be GCFI protected. New ABYC regs call for ECLIs to be installed on all new boats (basically a "whole boat" GCFI. (E-11.11.1)
 
#13 ·
As thekeip says, the DC and AC grounds must be bonded together as per ABYC. I use a 100amp BlueSea busbar to connect the AC, DC and the safety grounds that lead to my rigging together. I highly recommend a GALVANIC ISOLATOR on the AC ground, between the shorepower inlet and breaker panel, to reduce stray current that may be running around the DC system or in the water. It will save your zincs.
 
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