Warning! reverse polarity condition on AC Output - junbpaw 2080W RV Pure Sine Wave Inverter with ATS, Dual Voltage Power Inverter 24/48V

Just seen this come up in a few places and wanted to flag it here too — has anyone else noticed a reverse polarity condition on the AC output with the Junbpaw 2080W unit?

Been doing a lot of research for my van build and this caught my eye. The concern seems to be that under certain load conditions or ATS switching events, the Live and Neutral on the AC output can end up swapped. That's not just an inconvenience — it can be genuinely dangerous depending on what you've got plugged in, and some appliances won't flag it at all.

A few questions for anyone who's run one of these:

• Have you actually measured L/N polarity on the output with a socket tester?
• Does the issue appear consistently or only under specific switching conditions?
• Is it present on both the 24V and 48V variants, or just one?

For context, I'm comparing this against a Victron Phoenix for my build — yes it's pricier, but documentation and community support is miles better. Stuff like this makes me nervous about going budget on the inverter specifically. Happy to save money on panels or cable runs, but the inverter feels like the wrong place to cut corners.

Would be really useful if anyone with hands-on experience could chime in — especially if you've got a socket polarity tester result to share. Ebay ones are only a few quid and worth having if you're running any Chinese inverter units.

@Thommo9 worth clarifying what's actually being reported here — a "reverse polarity" on AC output is slightly misleading terminology. AC is alternating, so there's no fixed polarity. What people likely mean is swapped Live/Neutral, which is a genuine wiring fault and genuinely dangerous.

With cheap inverters from less established brands, this can happen due to:

• Incorrect internal wiring at the AC terminal block
• No neutral-bonding or incorrect bonding that confuses downstream RCDs
• Firmware defining output phase incorrectly

I'd test with a simple socket tester (around £5 from Screwfix) before connecting anything. If Live and Neutral are transposed, your RCD may not trip under fault conditions as expected.

Personally I moved away from unknown-brand inverters for anything permanent after a scare — Victron Multiplus units cost more but the documentation and safety testing is actually verifiable. For temporary/RV use, at minimum verify with a tester before trusting it.

@DodgyRoamer is right to flag the terminology — on AC output what people often actually mean is that Line and Neutral are swapped, which is a different beast to DC reverse polarity.

Worth checking with a simple socket tester (the little plug-in ones from Screwfix are ~£5) — it'll immediately tell you if L/N are transposed.

That said, on cheaper inverters I've seen the transformer winding or output bridge configured such that what's labelled "neutral" is actually sitting at 230V relative to earth. This is genuinely dangerous for anything with a Class I metal chassis plugged downstream.

Running a Victron MultiPlus myself and the output labelling is consistent, but I've bench-tested a couple of budget units that had exactly this issue out of the box. A £2 socket tester potentially saves a very bad day — highly recommend anyone with this unit checks immediately before connecting anything else.

Jumping in here because I'm in the middle of spec'ing an inverter for my garden office build and this thread came up in my research.

Can someone clarify — is this a known batch issue or is it appearing across the board with the Junbpaw 2080W? I'm trying to work out whether it's a quality control lottery or a design fault.

Also, practically speaking for a fixed installation like mine, would a Victron Phoenix at a similar wattage just be the safer route? I know it's a significant price jump but I'd rather not be rewiring things because a cheap unit has done something weird with its AC output.

What's the actual risk to connected equipment if the L/N are transposed — does it depend entirely on what's plugged in?

Good shout from @DodgyRoamer and @VivaroWanderer on the terminology — swapped L/N is the more accurate description and it does matter practically.

Had something similar crop up with a cheaper unit in my motorhome build a couple of years back. Certain appliances with Class II double-insulated casings won't care, but anything with exposed metalwork that relies on neutral-earth bonding for safety absolutely will. My Victron MultiPlus handles this correctly out of the box, which is partly why I ended up going that route despite the price premium.

@Bomber — if you're spec'ing for a garden office, this matters more than it would in a vehicle. Fixed installations have stricter earthing expectations. Worth checking whether any prospective unit ships with a properly configured neutral-earth bond or whether you'd need to add one externally. Don't let a bargain inverter become an expensive lesson.