Like 'ground' systems, marine systems are required to connect neutral to ground at the source of power, whether that is somewhere at the top of the dock for shore power, or at the generator or inverter. One of the most important connections at the inverter is from chassis ground to the boat's grounding bus. On a marine inverter, there should be a switch that opens the ground to neutral connection when it is providing pass-through shore power and closes it when it is generating AC power itself. I presume that the WM 1kW versions have a neutral/ground connection within them, but it would be very worth checking!
Tim Ex-Mojito Newport, RI > On Oct 24, 2016, at 2:31 PM, Michael Brown via CnC-List > <cnc-list@cnc-list.com> wrote: > > Hopefully the inverter will come with very clear instructions on how to > handle ground and neutral. > > For normal power, ie shore power, this is the US code: > > "The National Electrical Code ( NEC ) requires the AC source to have a > Neutral to ground bond > and that there be only one such bond in the entire AC system." > > So only at the distribution panel is there a bond between neutral and ground. > They should > never be connected together intentionally at the load. This document covers > grounding and > bonding, may also cure insomnia. > > https://www.engineereducators.com/docs/groundingandbonding2-2.pdf > > Grounding an AC system is done to limit the effect of a lightning strike, > maybe an upstream > over voltage fault. Bonding the green wire that comes in a three prong plug ( > also called a > ground ) to Neutral at the distribution panel is to ensure a low resistance > return path for > a fault. So if anything happens the desired effect is that a hot to ground > short will occur > which in turn will cause an over current surge blowing the circuit breakers. > > A person can be electrocuted even with a properly installed and grounded AC > system > without the circuit breakers tripping. > > Unless an inverter has some specific design that uses a ground bonding the > Neutral and > ground together is not going to do much. Check out the last Q&A from Xantrex > here: > > http://www.xantrex.com/documents/tech-doctor/universal/tech4-universal.pdf > > Similarly with an inverter connected to a battery that is not grounded a GFCI > should > never trip. Theoretically in a floating system the power has to come out of > the Hot > lead and return in the Neutral. There will never be a ground fault to trip a > GFCI. > There is no ground. > > I suppose an inverter manufacturer could create a third connection back to the > power circuit Neutral that bypasses the GFCI. A short to that wire would cause > an imbalance and trip the GFCI. Then you would be connecting a floating > Neutral to the loads "ground" which may be exactly what the Xantrex article > says > not to do. > > Michael Brown > Windburn > C&C 30-1 > > > > > From: Ron Ricci <rvri...@gmail.com> > > David, > > I've followed some of this thread and have a few concerns where some have > mentioned using an inexpensive inverter. > > Using an inverter that is not intended for marine use or not properly > grounded can cause problems. An inverter can produce short duration spikes > which exceed the insulation rating of most wires. This becomes an issue in > wet areas and will cause insulation failure. > > There are other issues relating to inducing corrosion. A friend who > coincidentally keeps his boat in RI and is the technical support guru for a > company that sells variable frequency drives (inverters for AC motors) had > to replace his propellers when he used an inverter he bought from Harbor > Freight. It was probably fine for anything other than marine use. > > If the neutral on the inverter is not grounded, the neutral can kill you > regardless of the presence of a GFCI. > > Just my thoughts, > > Ron Ricci > S/V Patriot > C&C 37+ > Bristol, RI > _______________________________________________ > > This list is supported by the generous donations of our members. If you wish > to make a contribution to offset our costs, please go to: > https://www.paypal.me/stumurray > > All Contributions are greatly appreciated!
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