Question on Shorepower/Inverter & AC Outlets

[fthurlow]

I have a question regarding shore power and the AC outlets on my 2010 lagoon 400. Let me give you some background first -
* this boat was originally wired for 240V European but has had both shore power plugs changed to accept 240V US
* The original inverter (240V) malfunctioned and was replaced with a Xantrex 2000w 120V unit (planning to change all AC outlets from 240V to 120V)
* the person who installed the inverter disabled the shore power/inverter transfer switch so that someone couldn’t “accidentally” feed 240V to the AC outlets
* I would like to be able to “pass thru” the shore power to the AC outlets and not use inverter when plugged in
* I think that I will need to create or locate a 120V circuit and connect it to the transfer switch
* What is the correct/safest way to accomplish this? Is this something I can do or should I seek a qualified electrician to take care of this?
Thanks in advance for sharing your knowledge/experience

[DeValency]

The simple solution is a source switch selector. It is like the battery selector but made for high voltage. It is a very common switch you can find in any professional electric supply store. It need to be rated to your expected power consumption out of the outlets, guess up to 50A?

Just note that if you now use 115VAC appliances and devices out of the outlets, the current is going to be twice the originally designed wiring were made for, so unless the devices require low power, such as usb chargers etc. you may need to upgrade the wiring to carry the higher currents as well as the internal shore power breakers etc.

[fthurlow]

I think I can use the existing switch but need to connect 120V where the 240V was connected. Then the AC outlets will get 120V if on shore or inverter, right??

[DeValency]

Correct. Not sure, however why the electrician updating the wiring before didn’t do that

[sailormed]

What DeValency is saying that 220V wiring can NOT carry the same power under 110V. If your coffee machine is 1000W under 220V is needs say 1 square mm wiring. But now on 110V the same coffee machine needs double the load carrying surface, so 2 square mm. So you need to replace the 220V wiring if you want to keep the same appliances, coffee maker, water kettle, induction plate etc. If not you have a big fire risk, melted wire isolation......

[smac999]

You don’t just locate a 120v circuit. 15a is not enough to charge and Pass through. You’d want at least 30a. Taken from the main ac bus. With its own input inverter breaker.

Is there 120v on the boat? Or did they only bring in the 2 hots and ground and the boat is still 240 only?

My guess is there is no 120v on the boat. Except from the inverter.


Is there an iso transformer?

Lots of things to figure out before adding.

[fthurlow]

Thanks, sounds like I need an electrician to check all of this out to be sure/safe

[fthurlow]

Ok, got it. Thanks

[jhilley]

You would have to change the coil on transfer switch to 120 vac. May just be jumper, may need to be changed out.

[wingssail]

Originally Posted by fthurlow

... the person who installed the inverter disabled the shore power/inverter transfer switch so that someone couldn’t “accidentally” feed 240V to the AC outlets...

I don't know how this "disabling" was performed. Is there a setting? or some modification done inside?

Or what the installer was thinking about the risk of feeding 240v to the outlets. I don't think a modern 120v inverter/charger will transfer 240V; it will not meet the high voltage limits and other validation which occurs when the voltage is sensed.

I think that the "disabling" can be safely reverted and the device will then pass through 120v automatically, and it will validate the AC supply as it does so.

I would not hook up to 240v shore power intentionally or otherwise unless you have a transformer to step it down to 120v. This is less critical if your shore power goes directly to the inverter/charger because that will validate the voltage and stop it. But a manual switch to shore power, (not using the inverter/charger) would supply 240V to the outlets and will likely damage anything plugged in.

I would be very careful about the adequacy of your wiring when running high wattage AC devices, either on pass through or on inverter, since your boat was wired for 240V, the wire sizes may be too small.

[wingssail]

Originally Posted by jhilley

You would have to change the coil on transfer switch to 120 vac. May just be jumper, may need to be changed out.

Why would this be needed if the inverter/charger was a 120v unit?

[Captain Anthony]

following

[Heathenly Twins]

I would highly recommend asking a well respected ABYC certified marine electrician on this matter, getting this wrong could mean serious injury or death to you or your passengers.

[roland stockham]

North American 120v systems use an entirely different design to 240v systems. The two are not compatible. It is possible to make your 240v wiring pas 120v but it will not meet any code requirements and could be dangerous to guests. Only solution is to rewire either replacing the existing system or adding a new 120v setup

[Boatwright]

Originally Posted by Heathenly Twins

I would highly recommend asking a well respected ABYC certified marine electrician on this matter, getting this wrong could mean serious injury or death to you or your passengers.

This topic has come up frequently. In short: There is no simple and most importantly safe way to switch European voltage systems over to the N. American standard. Get a certified marine electrician.