Right, let's talk about this PEN switch nonsense

There's a change on the cards that every sparky and solar installer in the country should have half an eye on, and frankly, I think it's a shocker of an idea (pun very much intended). WorkSafe wants to lift the ban on switches in the PEN conductor, pencilled in for November 2026. Having had a proper look at it, I reckon they should leave well enough alone.

Quick refresher for anyone who's forgotten the why behind this rule: AS/NZS 3000 says no switch, breaker, or fuse goes anywhere in the PEN conductor upstream of the switchboard. Full stop, no exceptions. That's not red tape for the sake of it — the PEN is carrying your neutral current AND doing the job of your earth reference at the same time. It's one of those rules that's boring right up until the day it saves someone's life.

WorkSafe's pitch is that "modern energy systems" — solar, batteries, EV chargers, backup power — sometimes want to switch the PEN, say when a system's flicking between grid and off-grid supply and needs to isolate the neutral-earth bond. They've got a review that says the advice is "technically sound and justified." Fair enough, on paper.

Where it falls over in practice

If that PEN switch fails open — or someone just flicks it — while the phase is still live, your neutral current's got nowhere to go. Every bit of earthed metal on the job goes live: appliance casings, steel roofing, solar frames, the lot, potentially at full phase voltage.

This isn't a "what if." Electrical/industrial engineer Daniel Müller actually ran the test — RNZ picked it up. Isolated everything bar a toaster, threw a simulated PEN switch, and the toaster's casing lit up at roughly 200 volts. That's someone standing barefoot on a wet floor grabbing the toaster and getting a proper hiding. This isn't a slightly worse version of a fault we already live with — it's a brand new way to get someone killed.

And it gets worse, not better

• The Aussies won't touch it. We share AS/NZS 3000 and most of the rest of the standard with Australia, and their version doesn't allow this. So we'd be going it alone here, in the wrong direction.
• We've got steel roofs everywhere. Especially up here in Taranaki. A live steel roof is about the worst-case scenario for this kind of fault — way more exposure than most other countries would be dealing with.
• This isn't a lone voice complaining. Engineering New Zealand's CE has gone to the Energy Minister directly asking for the ban to stay, saying every single expert they spoke to called this "unnecessary and inherently unsafe." NZ Solar Association's flagged the same rooftop risk. Inspectors were raising this months before it went public.

Where it stands, and what to do about it

For now — nothing's changed. The ban still stands, and the Minister's kicked the whole thing back to MBIE for another look, so November 2026 isn't locked in stone. But if you're speccing anything with backup power or transfer switching that touches the neutral-earth bond, give it its own risk assessment regardless of what ends up "allowed." Especially on steel roofs. And don't build your plans around that November date — wait and see what MBIE actually comes back with.

This reflects SolarLink's own view as of August 2026, based on available reporting. It hasn't yet been cross-checked against WorkSafe's or MBIE's own consultation documents or the actual gazetted AS/NZS 3000 wording — to the maximum extent permitted by law, SolarLink does not guarantee this page is current or complete, and installers should verify against primary sources before relying on it for compliance decisions. We'll update this page once MBIE reports back.

Sources

• RNZ, Phil Pennington — "Electrical expert's experiment with soon-to-be unbanned switch sends 200 volts to toaster"