Müller explained to RNZ how he simulated at home inserting a switch in what is called the “protective earth neutral”, or PEN, that is a shock blocker for most households and businesses.
“What I did was, I isolated all the loads except for a toaster.”
The electrical and industrial engineer then threw the switch. Two hundred volts went through the toaster.
“That means that if you touch that and you stand barefoot on the ground, you would get an electric shock that could potentially kill you … and what’s more, the fridge, the drill in the garage, everything that’s earthed is live.”
“Sound and justified”
WorkSafe advised the Government at the end of last year in favour of lifting the total ban on putting any switch, circuit or fuse into mains power earthing systems at the transmission side of house switchboards. As things stand, that would be lifted this November.
The agency said after concerns were raised it sought an independent review which in April confirmed its technical advice was “technically sound and justified”.
“The changes support modern energy systems, including renewable generation, battery storage, backup power, and electric vehicle charging, and enable safer, more resilient electricity supply,” WorkSafe said on Thursday in a statement.
Solar no-no
Glenn Harvey, head of the Solar Association, said the change would instead add new dangers.
“If you’ve got the neutral broken, and the phase is live, it’s coming into your house, and it can’t go back out because there’s a failed switch open and it electrifies all your electrical appliances, and your roof, and everything, it’s pretty dangerous, eh,” Harvey said.
“And that’s why the Aussies don’t accept it. They just think that there’s a fundamental core – you need to have that earth, that clean earth.”
New Zealand, with its many steel-roofed homes, made that imperative on a clean earth yet more important, he said.
Electricians who installed solar panels in homes were telling him New Zealand should not go its own way on the PEN when otherwise it had a joint solar standard with Australia, Harvey said.
Electrical inspectors came out strongly against the change months ago.
WorkSafe responded with April’s independent report and what it said would be careful guidelines.
‘Wrong-side failure’
But on Friday, Engineering New Zealand chief executive Dr Richard Templer upped the ante.
“We are very concerned that from the middle of November, people could start switching the protective earth neutral.”
He released a letter he sent last month to Energy Minister Simeon Brown calling for the urgent reinstatement of the switch prohibition.
“It creates a new wrong-side failure mode that did not exist before,” the letter said.
Every electrical expert they had talked to considered lifting the ban “unnecessary and inherently unsafe because of the risk of serious injury or death”, Templer said.
There were other safe ways of achieving the same things around solar and EV power.
“We are calling for the urgent reinstatement of the prohibitions in the standard before somebody suffers significant harm.”
The other worry was how the country got to this point – the critics say WorkSafe didn’t get enough expert input. The agency rejects that.
“We’ve had a lot of conversations with WorkSafe,” Templer told RNZ.
“We’ve done our absolute best to try and convince them that this is an unsafe thing … that’s what’s been going on for months.”
Brown said he had sought advice from the Ministry of Business, Innovation and Employment.
Templer said Brown told them the issue was being sent back to officials.