Adding Inverter to Boat Electrical system

[searenity38]

At my AC panel I turn off the main AC breaker coming into the boat. I have a short power cord with a mail end on each end. I plug one onto my 1000W inverter and the other end into one of the boat's outlet. This energizes all the outlets etc on that particular circuit
In my case I only have one AC circuit so now all my outlets are hot. I have a cap that I put over the main breaker that reminds me to disconnect the cords on the inverter before I hook up to shore power.

[LostDog88]

Originally Posted by searenity38

At my AC panel I turn off the main AC breaker coming into the boat. I have a short power cord with a mail end on each end. I plug one onto my 1000W inverter and the other end into one of the boat's outlet. This energizes all the outlets etc on that particular circuit
In my case I only have one AC circuit so now all my outlets are hot. I have a cap that I put over the main breaker that reminds me to disconnect the cords on the inverter before I hook up to shore power.

While I did consider this as an option, as an electrician (on land) I can tell you it is never a good idea to create a "dead mans" plug.

But I have done it before and it works perfectly.

I'm looking for more of an auto situation.
https://www.cruisersforum.com/images/icons/icon10.gif

[rslifkin]

Wanting it to be automatic is why I built the sub-panel setup I did. The loads on the inverter sub-panel automatically transfer to inverter power (via the inverter's transfer switch) when power on the L1 bus drops offline. I still have to manually select between the shore inlets and the generator for power source, but the inverter operation is automatic.

[john manning]

My first thought was that you need a power supply selector switch between the AC supply and your fuse board. This should be a three position switch with a off position between the supply choices.

On reflection I think what you really need is an electrician.

AC power from inverters or generators is dangerous. On boats it has the added complication of running without an earth line. Above earth power supplies need to be set up with bonding between all AC devices including the supply and modern safety standards would use an RCD as well.

[mitiempo]

Originally Posted by searenity38

At my AC panel I turn off the main AC breaker coming into the boat. I have a short power cord with a mail end on each end. I plug one onto my 1000W inverter and the other end into one of the boat's outlet. This energizes all the outlets etc on that particular circuit
In my case I only have one AC circuit so now all my outlets are hot. I have a cap that I put over the main breaker that reminds me to disconnect the cords on the inverter before I hook up to shore power.

That leaves none of the outlets protected by a breaker. Not a good idea.

[rslifkin]

Originally Posted by mitiempo

That leaves none of the outlets protected by a breaker. Not a good idea.

With only a 1000w inverter, assuming it has overload protection, it's not a problem. The outlet circuit is likely good for 15 or 20 amps, so the inverter can't put out enough to overload the wiring.

Of course, the inverter plugged into outlet setup isn't a good idea for plenty of other reasons.

[mitiempo]

Originally Posted by rslifkin

With only a 1000w inverter, assuming it has overload protection, it's not a problem. The outlet circuit is likely good for 15 or 20 amps, so the inverter can't put out enough to overload the wiring.

Of course, the inverter plugged into outlet setup isn't a good idea for plenty of other reasons.

Overload protection in an inverter will protect the inverter. Not whoever is using the outlet. If it has a GFCI there is protection to the user but if not it doesn't.

[rslifkin]

Originally Posted by mitiempo

Overload protection in an inverter will protect the inverter. Not whoever is using the outlet. If it has a GFCI there is protection to the user but if not it doesn't.

Very true. But many boats have non GFCI outlets anyway.

[mitiempo]

Originally Posted by rslifkin

Very true. But many boats have non GFCI outlets anyway.

Yes but the outlets are on a breaker. That is the safety.

If the inverter has a GFCI the outlets it is plugged in to will be protected. If not they will not be protected.

Powering outlets with a double male cord from the inverter the current does not go through the breaker on the panel.

[sailinglegend]

Originally Posted by LostDog88

...How the heck do ya'll wire in an inverter so that the outlets you use when plugged into shore power work when you are not on shore power?

Originally Posted by rslifkin

In that case, choose an inverter with a built in transfer switch. Personally, I'm putting in a Victron Multiplus 12/2000/80.

The advantages of the Multiplus system needs to be further explained because it can solve all of the OPs problems without any external switches or major wiring changes to the AC sockets.

Charger/inverters like the Victron MultiPlus, and also the Mastervolt Combi, can supplement the shore power AC by producing AC from the batteries, via the inverter, when extra load is needed. They do this by always staying in sync with the shorepower phase.

This is called "Power Assist", so the unit is installed in “series” or "in line" with the shorepower circuit. This way all AC outlet sockets get either shore power or inverter power automatically. For example, where pontoons have 10 amp breakers and 12 amps is demanded by the boat loads it can supply the extra 2 amps AC load from the batteries. This happens in milliseconds without blowing the horepower breakers. When the load falls below 10 amps it goes back to charging the batteries.

[manitu]

You need an electrician! There are lots of ways to kill yourself , or others , if you get this wrong.

You need to pay special attention to the earth to neutral connections. Earth connected to neutral is called TN (terra neutral). Both most inverters and most gensets have neutral connected to earth, BUT you need to be absolutely shure of this. my paguro generator was wired to earth at the center of generator coil . I had disconnect this , and connect earth to neutral outside the genset. You should only have neutral connected to earth at one single spot, at any given time. You must have a GFCI breaker between the earth-neutral connection and the panel/outlets.

Even a "working" system can be dangerous if you connect to a shorepower connection with inverted polarity, generator with IT (isolated terra) output, or a floating earth.

Get an electrician to: Install a isolation transformer, and wire it in TN fashion, to match the earth wiring in your inverter.
Wire your generator in TN (terra neutral) fashion, same as your inverter.

Now, all of your A/C sources has the same earth system , earth connected to neutral. The isolation transformer isolates the boat from earth-faults on land, and takes care of the dreaded inverted polarity.

.manitu

[rslifkin]

Originally Posted by sailinglegend

The advantages of the Multiplus system needs to be further explained because it can solve all of the OPs problems without any external switches or major wiring changes to the AC sockets.

Charger/inverters like the Victron MultiPlus, and also the Mastervolt Combi, can supplement the shore power AC by producing AC from the batteries, via the inverter, when extra load is needed. They do this by always staying in sync with the shorepower phase.

This is called "Power Assist", so the unit is installed in “series” or "in line" with the shorepower circuit. This way all AC outlet sockets get either shore power or inverter power automatically. For example, where pontoons have 10 amp breakers and 12 amps is demanded by the boat loads it can supply the extra 2 amps AC load from the batteries. This happens in milliseconds without blowing the horepower breakers. When the load falls below 10 amps it goes back to charging the batteries.

In my case I explicitly disabled that feature. I'm only powering outlets and a couple of lights through the inverter, so it won't cover my big draws like the water heater, A/C, electric stove, etc. So the assist isn't very useful to me.

I've got twin 50A / 125V shore power and the inverter only part of 1 of those legs. If I'm at a dock with twin 30A, managing power to stay within that is no big deal. If I'm stuck with a single 30A, then I'm pretty limited, but the inverter assist wouldn't be all that helpful. I just end up firing up the generator if I need more power for a little while (6.5kw, so 54 amps total to distribute however I want across the 2 legs).