Inverter AC wiring issues.

[Privilege]

Please help me identify my inverter AC issue...
I'm reconfiguring the panel so that the lighter AC loads are on one side so that I can hook up my inverter to that side only. I connected everything up and when i turned it on the inverter worked just fine. When I turned on the AC (with the inverter connected but off) the inverter did its best to self combust and has now been sent to inverter heaven.

I have a separate charger so my inverter is inverter-only with no internal switching as I'm happy to manually switch it off when connecting to shore power. When I connected it to the panel, I wired it directly to the live and neutral on the same side of the dual breaker on the same terminals as the shore input. I'm guessing that this was my mistake but I don't know why.

I'd appreciate any guidance.

[Corvidae]

Judging by that diagram you have the shore power connected directly to the output of the inverter. You need a transfer switch so the two of them are never connected to the circuit at the same time.

Of course that's going by a best guestimate of your drawing without actually seeing how things are actually wired.

[Privilege]

You’re correct, they are connected. So, you can’t have them connected, even if they’re not turned in at the same time?

[Stu Jackson]

Originally Posted by Corvidae

Judging by that diagram you have the shore power connected directly to the output of the inverter. You need a transfer switch so the two of them are never connected to the circuit at the same time.

Of course that's going by a best guestimate of your drawing without actually seeing how things are actually wired.

My thoughts, too.

[CaptNemoO2]

Not sure if inverters can take power coming into their outputs or not (I would think they can't) but if your diagram is how you have it wired, your shore power inlet will have live pins when the inverter is on. Simple solution is a transfer switch, either manual or automatic.

[Corvidae]

Technically it would depend on your particular inverter if it had protection when shut down. Most likely though, it took the entire capacity of the shore power it was able to pull across your wires, and melted the smallest ones in the path until the circuit opened again. The breaker on the shore power pedestal is also always suspect, they can and will melt closed, dumping every amp of power into your boat. They get as much corrosion as your boat, and often far less maintenance.

Personally I use two of these:
https://smile.amazon.com/Technology-.../dp/B00PVG2I3A

One switches shore/generator, the other switches that input with the inverter. Mainly because I've had problems with pass through on multiple inverters. So now I never use pass through. When my shore power or generator is running, they supply power to the boat. The inverter only supplies power when there is no other power source. I've heard some folks really don't like the auto switches, and prefer the manual. I understand the caution, but I've had zero problems with them for 3 years of continuous use living on the boat. And I can always hard wire one if I have to in an emergency.

Slap the right sized breakers on those, and a galvanic isolator on the ground, then enjoy a beer.

[Privilege]

Thanks for all your help. I found my answer and I'll install a transfer switch. I've learned that you can NEVER, not even for a second, have an AC source connected to your inverter output even if its turned off (unless you have an inverter charger with transfer switch built in).

[Corvidae]

Just remember if you do get an inverter/charger, the charger portion will always be on, and it counts towards the total load on the circuit. This is part of the reason I never use the built in transfer switch. They size the chargers to work quickly, which means they eat half the capacity of the circuit, without you really realizing it. So you turn on your normal stuff that uses maybe half your capacity, and all of a sudden things are melting, and breakers are popping. That's why I have two transfer switches, so I can shut off the inverter/charger entirely while on shore power, and my air conditioners won't melt the circuit, because the battery charger decided to wake up at the same time.

[captstu]

I use a n ordinary double pole double throw center off switch rated at 30 Amps - looks like an ordinary home light switch with a heavy duty rating to switch both the neutral and hot wires on one leg supplied by the inverter (a generator in my case).

You must absolutely lockout circuits so only one a/c source is connected at a time - and never to each other.

[Boatyarddog]

Originally Posted by Privilege

You’re correct, they are connected. So, you can’t have them connected, even if they’re not turned in at the same time?

Did your inverter have a shore pwr connection, internally?
Or was it 12 volt to 120 vt only.

You said it had a charger incorporated within?

You certainly cannot just wire an extension cord plug to 120 and then plug it into the output of the inverter, as it looks like in this depiction you've provided.

Most inverters have a hard wire input for shore pwr.
Boatyarddog

[Cadence]

Originally Posted by Corvidae

Judging by that diagram you have the shore power connected directly to the output of the inverter. You need a transfer switch so the two of them are never connected to the circuit at the same time.

Of course that's going by a best guestimate of your drawing without actually seeing how things are actually wired.

[Stu Jackson]

Originally Posted by Corvidae

Just remember if you do get an inverter/charger, the charger portion will always be on...
.....................
................

So untrue, sorry to say.


I have a Freedom 15 with a Link 2000 controlling it. I can turn the C or the I on and off from the Link.

[Boatyarddog]

Originally Posted by Cadence

On a marine inverter, the transfer switch is usually built in ?
I would think you'd only need a transfer switch if you've got a genset on board.
Inverters are 12/24 Vt. DC to 120 60 hertz. AC
https://www.fisheriessupply.com/marine-inverter-basics
Some may have a switch on them to accomplish the same result.
Boatyarddog

[goboatingnow]

On a marine inverter, the transfer switch is usually built in ?

no , in general the opposite is more likely until you to quite large invertors, becuase for smaller invertors (<2000W) you are very unlikely to simply allow then to feed into the boats mains circuits and they are much more likely to be used standalone , feeding a set of dedicated outlets . Personally I never feed invertors into the boats mains circuits

Of course its entirely possible to design and build invertors that can handle remaining connected to the mains ( either on of off ) these are typically called Grid-tied and tend to be the preserve of domestic PV installations . Proper Grid Tied units can synchronise with the incoming mains. Victron has a model or two that can do the same thing

[Boatyarddog]

Originally Posted by goboatingnow

no , in general the opposite is more likely until you to quite large invertors, becuase for smaller invertors (<2000W) you are very unlikely to simply allow then to feed into the boats mains circuits and they are much more likely to be used standalone , feeding a set of dedicated outlets . Personally I never feed invertors into the boats mains circuits

Of course its entirely possible to design and build invertors that can handle remaining connected to the mains ( either on of off ) these are typically called Grid-tied and tend to be the preserve of domestic PV installations . Proper Grid Tied units can synchronise with the incoming mains. Victron has a model or two that can do the same thing

Well, of course one would have their AC circuit supply the AC voltage thru a Circuit breaker. This would come thru your AC panel as Inverter Power.
One would never wire an unprotected circuit into the boat. Right?
Boatyarddog