Grounding DC & AC systems during Repower

[JohnV8r]

Hey Guys,

Is there a safe way to ground my AC side once the 454's are pulled so that I can run my battery charger and use power tools via the plugs?

Currently my AC and DC systems ground on the engine block. I know from experience that the DC side will function when the shore power is plugged in and the batteries are not grounded to the motors. However, I want to make sure I don't electrocute myself using the AC side while the motors are out and I am prepping the bilge area and engine beds.

Shambala will go back in the water after the engines are pulled. That will give me the ability to use the shore power to provide electricity. I just need to figure out how to do it safely.

Thanks in advance.

John Vietor

[Charlie J]

john
don't see a problem
but I would tie the 2 separate grounding cables together that came off the engines
this way your grounds are not open and has a path back to your ground from the shore cable.
bob lico what do you say

[Tony Meola]

I am not an electrician but when I looked at the instructions for installing a Galvanic Isolater they tie the ground from the AC panel back to the block, or I would assume the you could go to the bonding system.

http://www.marinco.com/files/support/pr ... 531011.pdf" onclick="window.open(this.href);return false;

[bob lico]

By the numbers-------1, shore power cable from land source has lowest resistance (ohm's) then anything on boat.2, ground from shore power goes to W/P outlet in cockpit to main panel A/C ground bar (yes tony thru galvanic isolator) .3,ALL a/c grounds must terminate to this ground bar.4, DC is not a issue when boat is on hard just have main ground bar usually installed in top of first floor access as you walk in cabin .this is your starting point for DC ground then continuous 2/0 cable from all battery negatives (daisy chain in series ) to the to port engine block to starboard engine block.all the DC negatives from main panel and all auxiliary panels also terminate here. DC negative bar at main panel does not connect to a/c ground bar in main panel!!!! However if you have galvanic isolator you should connect a/c ground bar to Bertram bond strip that is installed on inside of stringers to main zinc on transom.my personnel tip; install separate 12 volt panel for electronics Do not bond to any system!! With fusible link in negative feed wire or isolated. You will be free from a hold slew of calamities at sea beginning with lightning .

[bob lico]

I should add all of you guys working on your boat on the hard should use the regular shore power cable ( 30ampere) with twist lock to 3prong U ground plug adapter and plug that into land power.all of the above post is meaningless with cheap ungrounded frayed cord connected to outlet on land. Use shore power to main panel a/c thru GFIC controlled outlets on your boat to work on boat in all conditions rain,snow,wet floors,whatever your safe.absolutely must use bertram a/c outlets to work on boat. your life depends on that continuous ground throughout boat outlets going to land ground.normal procedure at oakdale Yacth is for the maintenance supervisor to cut the plug off every box store cheap cord connected to yard land power.you must use your shore power cord to back feed boat panel thus use your own GFCI protection. ------ you sigh contract yard policy from past injuries!

[JohnV8r]

Thanks Bob!

[Tony Meola]

I should add all of you guys working on your boat on the hard should use the regular shore power cable ( 30ampere) with twist lock to 3prong U ground plug adapter and plug that into land power.all of the above post is meaningless with cheap ungrounded frayed cord connected to outlet on land. Use shore power to main panel a/c thru GFIC controlled outlets on your boat to work on boat in all conditions rain,snow,wet floors,whatever your safe.absolutely must use bertram a/c outlets to work on boat. your life depends on that continuous ground throughout boat outlets going to land ground.normal procedure at oakdale Yacth is for the maintenance supervisor to cut the plug off every box store cheap cord connected to yard land power.you must use your shore power cord to back feed boat panel thus use your own GFCI protection. ------ you sigh contract yard policy from past injuries!

Bob

You put a fuse on the negative ground to the bonding system? What size fuse.. I would think pretty large even if it carries no juice. Outside of lighting what else could it prevent?

[bob lico]

This is just on the negative feed cable to the 12 volt electronic only panel mounted on bridge .protect GPS,,radar,VHF,displays no matter how much extra effort. Lets make this clear 12 volt DC bridge electronic panel. On positive leg should be isolation block ( one way diode) you will get the extra benefit of never ever seeing a blink when starting engines,generator,or shutting down and even switching power source