Positive ground system precludes use of shore power?

[dwest]

Current owner informs me the boat has a positive ground electrical system that is not compatible with shore power even through an inverter, except to run a charger for the house and other batteries. Good thing one of the team is an electrician because this is a new one to me.

So are we looking at replacing the electrical system, running a new one in parallel, to get the advantges of using shore power for things like heating and cooling, or just living with it somehow?

[carioca1232001]

.... the boat has a positive ground electrical system that is not compatible with shore power even through an inverter....... except to run a charger for the house and other batteries.

Boat with a positive ground means the positive terminal of the boat´s battery is connected to the earthing plate of the boat, much like in some cars of yesteryear (in the UK ?) - and unlike the practice in most other countries - that is, the negative battery pole connected to the sheet metal body.

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Shore power is AC (alternating current) and is supplied by a 'hot' wire, a 'neutral' wire and a 'ground' wire for 120 volts AC.

You can generate your own AC on board using an inverter, which is device that converts battery power to AC power. They usually have two lugs (terminals) for connecting battery power, plus another two terminals for supplying AC power to an external device.

All inverters that I have come across have their outer metallic casing isolated from the battery input leads, as well as the AC output leads. The outer metallic casing lug is connected to boat ground. One of the AC leads is 'elected' as 'neutral' and similarly connected to the boat ground.

You will need to exercise great care when connecting up to AC shore power, be your boat positive ground or negative ground; the object of this is to avoid creating a hazard for yourself or for others around your boat.

Good thing one of the team is an electrician because this is a new one to me.
So are we looking at replacing the electrical system, running a new one in parallel, to get the advantges of using shore power for things like heating and cooling, or just living with it somehow?

Show the above comments to the electrician and see what he has to say

[Hwyl]

Wouldn't the isolating transformer take care of most of the problems?

On another note, I converted my mini from positive ground to negative ground, by just turning the battery around. It had a dynamo (U.S. Generator) and no electronics (circa 1977). I wanted to fit a cassette player.

[carioca1232001]

Wouldn't the isolating transformer take care of most of the problems?

On another note, I converted my mini from positive ground to negative ground, by just turning the battery around. It had a dynamo (U.S. Generator) and no electronics (circa 1977). I wanted to fit a cassette player.

Frankly I see no problem with either positive ground or negative ground !

But, you are right, an isolating transformer t judiciously connected between the boat and the shore supply, would normally take care of the rest.

You are lucky to have got away with just flipping the leads around on that mini, but I suppose having 'zero electronic' content was the catch !

[P.I. Stazzer-Newt]

Wouldn't the isolating transformer take care of most of the problems?
....

I cannot think of any intrinsic reason why positive earth should preclude the use of shore power, but the comment from carioca1232001 is sound.


How old is the wiring? - the last Positive Earth car I met was pre 1970.

[Hwyl]

"You are lucky to have got away with just flipping the leads around on that mini, but I suppose having 'zero electronic' content was the catch !"

It was a company car, at age 26 that means zero risk!