Free Credit Report

Inverter Wiring Question

My boat has two 120 volt circuits with a common neutral wire similar to most homes. Normally they are supplied with 220 volts from either a generator or shore power (120-0-120). There are no 220 volt appliances or circuits out of the breaker panel.

I would like to be able to feed both 120 volt legs with a single 120 volt inverter through a rotary selector switch (both legs in phase, instead of 180 degrees out of phase). There would be no possibility of backfeed or cross connection with shore/generator power.

Does anyone know of any issues with doing that?

Hoo
Nov 14
2005
One mistake that I once made on my old boat was to accidently turn on the battery charger which caused the inverter and charger to chase each other and pull down the batteries pretty quickly but that's easy enough to spot if you are watching things. Hoo
Nov 14
Make damned sure this switch is a BREAK before MAKE affair or it will soon be welded shut!

I like the contactor approach, myself. You plug in shore power, the contactor closes hooking shore power to the panel until you unplug shore power, when it connects your inverter to the panel.....automatically....

No runs, no drips, no errors, noone left on 3rd base....goofproof.

Larry
Nov 14
In article <ceehn1hdg6gi1fme2p0dopm1fta9hnffps@4ax.com>, Peter Bennett <peterbb@nowhere.invalid> wrote:

The neutral question that Peter is concerned about would be dealt with, IF you drive your 120-0-120 panel with wire that would support the total current of all the loads at one time. I use this exact system for feeding the panel in my cabin from my Trace 4024. As the cabin was originally designed and fed as a 240/120Vac Single Phase, when I moved in and introduced the Trace inverter, rather than replace the panel, I choose to bring both legs together at the Transfer Switch that feeds the cabin. In Winter Mode, It is driven by 120Vac directly from the output of the 4024. In Summer Mode, it is feed by 208/120Vac, Two out of Three Phase, from the 2.5 Megawatt Powerhouse Distribution System. The feedwires to the cabin from the Winter Powerhouse are "2", so that there is plenty of copper for the maximum load of te cabin, and I have NO 240 loads on the cabin subpanel.

Bruce in alaska

Bruce
Nov 14
Agreed.

Bruce in Alaska wrote:

chuck
Nov 14
I can't think of any problems that might arise, as long as there is no possibility at all, ever, of connecting to 240 volt shore power with the two 120 volt circuits connected in parallel! Doing so would probably trip the pedestal breaker instantly before any real damage, but nonetheless something to be avoided.

Go for it.

Chuck

Hoo wrote:

chuck
Nov 14
My only concern would be the size of the neutral wire.

When fed 120-0-120, the neutral current can never be more than the current in either hot wire (it will actually be the difference between the two hot wires), but if the two hot wires are in phase, the current in the neutral will be the sum of the two hot currents.

If your inverter is 2000 watts or less, and the wiring is #12, you will be OK, as the inverter will limit the total current to about 20 amps, and #12 wire is rated for that. If you have a larger inverter, you may have to use larger wire.

Peter
Nov 14
   

Disclaimer: This is a computer-generated and formatted feed of current postings to a public
Internet forum. We do not control the information delivered, nor do we endorse or monitor its
content. Internet forums may carry offensive, harmful, inaccurate, and otherwise inappropriate material.
Click to see the RSS XML version of this page   Click to see the Atom XML version of this page