Thread: Sparkologists - 240V generators and RCD protection

will need an earth for the rcd to operate. generally an earth stake and some 6mm2 earth wire will do the trick.

not sure that you need it earthed, our generators at work are on trollies with inflatable tyres and we don't earth to the ground........out electrician do RCD checks every three months.

i might quizz them about it a bit more

My understanding is that they measure the difference between the current in the active and neutral lines, and if the difference is more than something ridiculously small, it triggers. So at that level, an earth connection should not be needed.

Having a path for the earth could improve the protection as it might give a path for current in case of a fault, which would trip the RCD without the need for a convenient person to touch the faulty device.

If the generator has an MEN link in it - that is if the neutral and the earth (the frame of the machine) are connected together, then you don't need an earth stake. The regulations for temporary power state in this case " an earth stake is not required nor recommended".

Unless the genset is hard wired to a switchboard that already has an MEN link in it, then your machine should have an MEN link anyway. The hard wired scenario with a switchboard MEN is the only one you need an earth stake for, despite what some inspectors say. Any fault currents generated that are not protected by an RCD will run back to the MEN point and effectively overload the genset and trip the breaker. Even if someone is touching the machine when this happened would not get a shock, as the power is following the path of least resistance.

But, as previously stated, the RCD works on an imbalance between active and neutral, so the earth stake is irrelevant for this. The RCD will operate as it should. If it is an off the shelf genset it will have the neutral and earth already joined. If you want to check this, with the machine off, use a multi metre to check the resistance between the neutral and the frame - it should be close to zero ohms. Make sure any circuit breaker is on when you do this, as the circuit breakers could be double pole units, and you may get a strange reading otherwise.

So, in a nutshell, no you don't need an earth stake. There is no safety or legislative requirement for one in your case.

Cheers - Gav.

Hi Steve and there is now a new Australian designed and world patented safety device that can be installed inside generators and inverters and makes them safe when using Class 1 devices.

The new device called RVD, is the only device in the world that that can make isolated power supplies like generators and inverters safe and once fitted, power boards can be used the inverter or generator.

Originally Posted by drivesafe

Hi Steve and there is now a new Australian designed and world patented safety device that can be installed inside generators and inverters and makes them safe when using Class 1 devices.

The new device called RVD, is the only device in the world that that can make isolated power supplies like generators and inverters safe and once fitted, power boards can be used the inverter or generator.

hey Tim, do you have any links for a bit more info.........i cannot find much apart from the bagging it gets explore oz.......yes is was back in 2010 so hopefully its been developed a bit more

Hi Kevin and these new devices are being supplied to the mining industry but at this stage I am the only one that has RETAIL access to gear with the RVDs installed but I’ll get some more info from the manufacturer.

I know a bit about the rhetoric on Explore Oz but I haven’t been on there for some time. This is a new device that only became available in July this year and the RVD is specifically designed to be used in isolated power supplies like inverters and generators.

Make yourself a cup of coffee and try here:-

Caravaners Forum • View topic - Generator and Inverter Safety

... and here if you feel like a second cup...

http://safe-electrical.mdz.com.au/wp...stry_Paper.pdf


If we're talking about 'residual voltage detection' devices, then Protex came up with this over 6 years ago...

http://www.ferret.com.au/c/Protectel...proved-n687162

- Don't know if they're still in business, as I was'nt able to find a current address... (sorry, despite my resistance it just slipped out.)