Adding Inverter to Existing System?

[Serene]

[SNIP]

Good luck with however you proceed. Inverters are great whether whole house or select circuits.

Peter

Thanks Peter. Appreciate your responses.

 

[ranger58sb]

One caveat with inverter/chargers: always turn the inverter or master selector switch off before connecting to a new shore power outlet. If it's a newer installation with an ELC (kind of like the GFI outlets in your home) installed, it might trip the ELC. Depending on how they set it up, that might take down just your outlet, or the whole dock, or the whole marina. You won't make friends that way.

???

That would seem to defeat a purpose for the internal automatic transfer switch.

-Chris

 

[ranger58sb]

Another thing I hadn't thought about! And yes would not want batteries drained when plugged into shore power that fails. But am assuming an inverter can be smart enough to be set to a mode to not invert, just pass through. So can enable this mode when alongside and the boat is left for any period of time.

More research needed.

Yes. Implementation probably depends on unit, and some installation details.

Our installation included an external monitor and an external controller, both mounted in the saloon for easy access. The controller has a 3-way switch: Don't invert/OFF/Invert.

If it helps your research, our hardware is:
- Victron MultiPlus 24/3000/70/50 120VAC
- Victron BMV-712 Smart Battery Monitor
- Victron Digital Multi Control GX Panel

The installation process was complicated enough (fusing, etc.) and access challenged (wiring, etc., through places I can't get to) so I chose to have it all done by local professionals. Wasn't particularly expensive, in our grand scheme of things.

-Chris

 

[sunchaser]

. One caveat with inverter/chargers: always turn the inverter or master selector switch off before connecting to a new shore power outlet. If it's a newer installation with an ELC (kind of like the GFI outlets in your home) installed, it might trip the ELC. Depending on how they set it up, that might take down just your outlet, or the whole dock, or the whole marina. You won't make friends that way.

Right you are. Once the new GFIC shore power installs started appearing a decade ago it became our standard procedure to prevent pedestal trips. As well we updated our vessel’s grounding system.

With a good BMK on/off the charger functions just fine even with the inverter switch off. Turning the inverter off whenever we left the boat for more than a day is SOP for us.

 

[rslifkin]

If an inverter is wired properly there is absolutely no need to turn it off before connecting shore power to avoid a trip. The big thing is that the neutral bus for loads run from the inverter MUST be isolated from the neutral bus the inverter draws from. If they're not, the inverter will have the neutral bus grounded before it switches to shore power. The GFCI / ELCI will see this and trip.

So if you have a single shore power input, you'd have 2 neutral busses. One for the shore input pre-inverter, one for things run through the inverter.

 

[sunchaser]

If an inverter is wired properly there is absolutely no need to turn it off before connecting shore power to avoid a trip. The big thing is that the neutral bus for loads run from the inverter MUST be isolated from the neutral bus the inverter draws from. If they're not, the inverter will have the neutral bus grounded before it switches to shore power. The GFCI / ELCI will see this and trip.

So if you have a single shore power input, you'd have 2 neutral busses. One for the shore input pre-inverter, one for things run through the inverter.

Sounds good but reality intrudes. Not all older vessels are wired perfectly. Not all inverters have a switching relay that is as fast as the 30ma dock relays.

Turning off the inverter before hooking up to shore power is so easy. Once shore power hooked up turning the inverter back on is usually ok, it’s just the initial plug in that sometimes proved troublesome.

 

[rslifkin]

Sounds good but reality intrudes. Not all older vessels are wired perfectly. Not all inverters have a switching relay that is as fast as the 30ma dock relays.

Turning off the inverter before hooking up to shore power is so easy. Once shore power hooked up turning the inverter back on is usually ok, it’s just the initial plug in that sometimes proved troublesome.

The switching relay doesn't need to be fast if it's wired properly. The dock breaker won't see anything it doesn't like, it just sees an increase in load when the inverter switches over.

I have seen issues when the neutrals weren't properly separated. I made sure they were for my install and I have plugged the boat in many times to docks with GFCI breakers in different locations (including our home slip) and never had one trip. In our case, the inverter gets turned on when we launch the boat in the spring and I don't normally shut it off until we haul for winter.

Plenty of older boats are wired poorly and have issues with GFCI dock breakers. But work-arounds aren't the answer here. The only proper solution is to fix the wiring on the boat.

 

[sunchaser]

RS
Work arounds are boating 101, especially those that take a few seconds to address. I’d guess you have a few yourself.

From what I’d seen, Magnum’s older inverters were problematic with the internal switching device. A decade newer Magnum worked much better with few if any trips noted.

BTW, those with ITs won’t be faced with the prospect of a two second “work around.”

 

[DavidM]

Check out an article I wrote a this topic. It can be found by clicking on the Library icon on the upper right of each page on this site. It can be found in the Misc section.

David

 

[Bmarler]

Most newer inverters don’t switch instantly when you plug in. They take a few seconds to qualify the power and sync the frequency and then switch. I suspect that lass sophisticated or older inverters may be more problematic on the gfci breakers.

 

[Serene]

My current procedure is to turn off all AC loads before disconnecting shore power and do the opposite when re-connecting, so not sure this will be an issue in my use case.