*Editor’s note: every week, AIMS Power will feature a “Tech TIp of the Week” that showcases a problem our technical support team has helped our customers solve.

QUESTION: Why is my receptacle (AC outlet) tester indicating an “open ground” fault when I test my DC to AC power inverter on a boat or RV after connecting to the vehicle’s chasse?

A receptacle, or AC outlet, tester plugged into an AIMS Power inverter indicating an "open ground" fault. It's impossible to get this indicator to shut off unless connected to a metal rod in the Earth, which is impossible in a boat and/or car that's moving.

ANSWER: When using a power inverter on a boat or RV, the tester will indicate an open ground fault. This is because it is not connected to a “true Earth ground”, meaning it is not connected to a metal rod stuck in the Earth. It would be impossible to do so in a boat or car while moving. For this reason, certain appliances and/or tools cannot be used while boating or driving. The power inverter DOES NOT and cannot create a true Earth ground on its own.

***However, the input electricity is partially grounded out by the negative DC connection and by mounting the inverter to a metal frame. These two safety precautions ensure the ability to use most of the appliances desired for a boat or RV. This is why it’s still okay, and standard practice, to use inverters in boating and RV applications.***

“City power is always grounded to a true Earth at your house, but if you’re in an RV, boat or something mobile, it’s not going to have a true Earth ground. That’s okay — just know that some devices need an Earth ground to work, such as the new, big, stand-up refrigerators,” AIMS Power’s lead technician, Andrew Frey said.