Difference between UL458 & UL 1741 For Power Inverters

According to the National Electrical Code, batteryless (on grid) or battery-based (off grid / hybrid) power inverter used in residential renewable energy systems must be listed to UL1741.

While UL458 is the safety standard for Power Converters/Inverters and Power Converter/ Inverter Systems for Land Vehicles and Marine Crafts.

UL458 listed Inverters are designed for mobile use—for example, on boats and RVs, which are sometimes off-grid without permanent grounding and sometimes hooked up to shore power/power grid for battery charging and to supply supplemental energy for AC loads. The UL 458 inverter is incapable of selling energy to utility.

The two UL standards differ mainly in two things. One is how they handle the grounding in AC system, the other is whether the battery charger is tested or not.

UL1741-listed inverters must allow for the neutral-to-ground bond to only occur at the main AC service panel. UL458-listed inverters have internal automatic neutral-to-ground switching relay. This relay allows for neutral to ground bonding to occur when the inverter is in off-grid DC to AC mode, it also separates neutral from ground at the utility power service if it is connected to a utility hookup. It does so because in mobile power systems, neutral is bonded with ground.

As for battery charger testing, UL458 doesn’t test the battery charger part of the inverter even some models are built with battery charger.

UL 1741 tests the battery charging part to make sure its safety standard is met.

Some inverters are listed under both UL458 and UL 1741 standards with a disconnectable cable near the AC terminal, so you’ll need to read the installation manual carefully about the step up.

An inverter model is either “UL listed” or “NON UL listed”, currently, Sigineer Power is able to List our inverters to UL458, UL1741 and CSA C22.2 under customer brands.

Contact us for more about UL listing at info@sigineer.com .

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