Ground Fault Basics: Inverter Grounding, GFI, wiring, and more

Posted on 2/12/2019 by Justin G. (Marketing)

A Ground Fault is caused by damaged wiring, faulty power tools or old appliances that allow electricity to take an unplanned path to a ground. Sometimes electrical appliance housings can become electrified that can lead to electric shock if you touch them.

 

 

Wagan Tech Pure Line Power Inverters item numbers: 3800 (400W), 3802 (700W), 3804 (1000W), 3808 (2000W), and 3810 (3000W) all have built in Ground Fault detection and AC shutdown features.

If a Ground Fault is detected, the inverter immediately shuts off AC power until:

1 - The Ground Fault has been removed.

2 - the inverter is reset by toggling the On/Off power switch.

This Ground Fault shutdown feature has caused some customers to wonder why their inverter has shut down although there is no evident ground fault.
It’s not a mystery; there are just too many grounds in their AC wiring!
You only need one ground on the AC side of the inverter; and the inverter provides this connection. Extra ground to neutral connections causes GF tripping.

 

 

Before we continue, note that it is Extremely Important that the reader is aware that this discussion makes distinction among the following ground points used in Inverter installations:

1 - Inverter Enclosure Ground Terminal.

2 - Ground terminal of the High Output AC terminal strip.

3 - Neutral Grounding Screw inside an electrical breaker panel box (if a Breaker Box is used).

4 - Earth Ground – water pipe, ground rod or battery negative terminal

The National Electric Code (NEC) for all AC distributed electric wiring states that the AC source (in this case a PureLine Inverter and most Wagan Tech Inverters) supplies the Neutral to Ground bond (connection).

Any Ground Fault detection will trip when it detects unequal currents flowing through the Hot and Neutral conductors. The assumption is that an unbalanced current flow is caused an unwanted electric path to ground, that is: a Ground Fault. Undetected Ground Faults can be lethal. If either the Neutral or Hot has any extra connection to ground - even as few as five milliamps of differential current flows, a Ground Fault circuit will trip.

If you inadvertently wire an unwanted extra path to ground, the Ground Fault will trip.

The inverter AC output terminals supply the Neutral to Ground connection and no other such connections are permitted.

All Ground Fault detectors do not need a ground wire connection as they sense differential current between Hot and Neutral. Ground wires are there to prevent equipment enclosures, aka“housings”, from becoming energized.

Therefore, the user must keep all Neutral wires separated from any Ground connections. This means that the AC Breaker Panel Neutral Bus bonding screw is not tightened to connect with the Breaker Box. And never put jumpers from Neutral to Ground wires in electric outlet boxes. Again, extra paths to Ground will trip the shutdown circuit.

 

 

How does the overall system get grounded? It is grounded by means of the Enclosure Grounding Terminal attached to the inverter. Connect a 6 AWG wire from the enclosure Grounding Terminal to any convenient Earth Ground point that includes: a metal water pipe, a ground rod, or other large metal mass that is partially buried in earth. If no suitable Earth Grounding point exists, then connect the enclosure to the battery bank's Negative Terminal.

 

NO SHORTCUTS

Do not make an enclosure grounding screw connection at the inverters negative battery terminal. Take the enclosure ground wire all the way to battery bank negative.

 

About AC Grounding.

Ground wires that either run parallel to or that are bundled with Hot and Neutral wires and are connected to AC outlets or appliances are never wired to carry current. Ground wiring that connects to appliance housing is to prevent the housing from being electrified and causing shock. This is independent of Ground Fault sensing and shutdown.

The one ground wire connection in this AC wiring discussion is a connection to the inverter's high output terminal strip. The terminal strip ground terminal is internally connected to the enclosure ground screw and that is connected to Earth Ground. So, there is a continuous connection from Earth Ground to the AC wiring ground wires.

 

 Blog by Jack C. aka "Professor Jack"

Links in this article:

Pure Line Inverter 400W
Pure Line Inverter 700W
Pure Line Inverter 1000W
Pure Line Inverter 2000W
Pure Line Inverter 3000W

If you have any questions related to Inverter Grounding, please contact Wagan Tech support at CustomerService@Wagan.com or by calling 1.800.231.5806.

 

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