Author Topic: Question about ground wiring  (Read 506 times)

elias

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Question about ground wiring
« on: January 18 2023, 20:59 »
Hi to all,
I am wondering ,how you setup the ground wiring when having an inverter on board ?

Does the DC negative coming in the inverter is also the GROUND of the AC produced?
There is a copper cable going to the keel bolts I can’t remember exactly from where ,I think from the negative .

In a new setup I made I have a dedicated lifepo4 battery to the inverter, charged only from dedicated pv panel and charger.

Domi409

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Re: Question about ground wiring
« Reply #1 on: January 19 2023, 23:10 »
Hello,
For my setup, the following are connected together:
- Service battery DC negative (so also inverter DC negative)
- Engine battery DC negative
- AC quay groung and all AC plugs ground
- AC neutral of the inverter
- Case of the inverter

It allows to make use of existing AC setup of the boat and differential protection.
Precaution to make: never plug shore and inverter at the same time.

elias

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Re: Question about ground wiring
« Reply #2 on: January 20 2023, 09:07 »
Hello,
For my setup, the following are connected together:
- Service battery DC negative (so also inverter DC negative)
- Engine battery DC negative
- AC quay groung and all AC plugs ground
- AC neutral of the inverter
- Case of the inverter

It allows to make use of existing AC setup of the boat and differential protection.
Precaution to make: never plug shore and inverter at the same time.
Same here except the casing , is Chinese one and there wasn’t any marked ground as the previous victron
The only thing about shore and inverter simultaneously is that a had an electrician that installed a 3 position lever for AC , SHORE - INVERTER - OFF , another relay I think that when senses inverter on disarms the shore power , and the AC battery charger is connected only to the shore power main .

Domi409

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Re: Question about ground wiring
« Reply #3 on: January 20 2023, 10:13 »
Hi, yes, I also have a 3 positions switch, Shore-Off-Inverter. In the inverter position it simultaneously switches off the battery charger AC input.
It allows to use the AC panel of the boat as if it was shore power. Only precaution is to switch off the water heater to prevent draining the service battery.

elias

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Re: Question about ground wiring
« Reply #4 on: January 20 2023, 10:20 »
You are right , it can be a major power loss ..I had the element changed to a 300watt for that reason…
Anyway , in your inverter the ground is just a screw in the case and then a cable to negative DC?

Domi409

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Re: Question about ground wiring
« Reply #5 on: January 20 2023, 10:39 »
Yes, correct. It is a Victron.

tiger79

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Re: Question about ground wiring
« Reply #6 on: January 20 2023, 11:30 »

The only thing about shore and inverter simultaneously is that a had an electrician that installed a 3 position lever for AC , SHORE - INVERTER - OFF , another relay I think that when senses inverter on disarms the shore power , and the AC battery charger is connected only to the shore power main .

I tackled the issue another way.  I hard-wired the inverter to 2 separate sockets, one in the heads for a hairdryer, one in the galley for the kettle/microwave.  No switches to mess about with, and the only load on the inverter is whatever is plugged into one of the dedicated sockets.

Domi409

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Re: Question about ground wiring
« Reply #7 on: January 20 2023, 12:39 »
Hi, yes, this is the other possibility. In this case, the AC is "floating", no common ground.
I did not do it that way to avoid installing a second AC panel with a differential protection.
Connecting the AC sockets directly is not a good electrical protection.

elias

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Re: Question about ground wiring
« Reply #8 on: January 20 2023, 15:17 »

The only thing about shore and inverter simultaneously is that a had an electrician that installed a 3 position lever for AC , SHORE - INVERTER - OFF , another relay I think that when senses inverter on disarms the shore power , and the AC battery charger is connected only to the shore power main .

I tackled the issue another way.  I hard-wired the inverter to 2 separate sockets, one in the heads for a hairdryer, one in the galley for the kettle/microwave.  No switches to mess about with, and the only load on the inverter is whatever is plugged into one of the dedicated sockets.



Ι see , it is indeed much simpler and convenient . But still you don’t have a ground ? Or the negative DC input acts in a way as ground ?
Domi , still in my system as the electrician said there is the original 220 AC safety relay BEFORE the plugs

tiger79

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Re: Question about ground wiring
« Reply #9 on: January 20 2023, 16:00 »

Ι see , it is indeed much simpler and convenient . But still you don’t have a ground ? Or the negative DC input acts in a way as ground ?


The DC negative is grounded and the inverter case is connected to it.

Domi409

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Re: Question about ground wiring
« Reply #10 on: January 24 2023, 14:34 »
One should read the Victron documentation before connecting an inverter and connecting to earth a floating AC. See page 69 for example.
The doc is well made and covers many cases. It exists in french as well.