Sparkologists - 240V generators and RCD protection

[roverrescue]

Just a quick one for the Sparkologists

I assume for a "safety switch" to actually be of use when connected to a 240V portable generator.

The earth connection of the generator must be connected to a ground spike.

Can I just use a short length of wire and copper bar belted into the ground next to the generator? If it matters camp is on soft sand.

Will it matter if the potential leakage (electrocution event) to earth is 30-40m distant to the gennie and earth spike?


Just want a little bit of protection at family camp this year with 7 rug rats running around and a rats nest of 240 powering the fridges and fans. I notice you can buy inline RCD that should easily plug into the output receptacle of the Honda 2kVa.

Opinions besides shooting or blowing up the generator would be appreciated ;)

Steve

[Vern]

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

[weeds]

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

[Pinelli]

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.

[Homestar]

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.

[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.

[weeds]

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

[drivesafe]

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.

[superquag]

Make yourself a cup of coffee and try here:-

Caravaners Forum • View topic - Generator and Inverter Safety (http://caravanersforum.com/viewtopic.php?f=2&t=8782)

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

http://safe-electrical.mdz.com.au/wp-content/uploads/2012/09/SET_Mining_Industry_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/Protectelec/Protex-now-Australian-Standards-approved-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.)

[isuzurover]

...ground spike.

... soft sand.


If you go down this route, bear in mind that in WA, all earth spikes are also connected to the (copper) water pipes. Dry sand is not a good earth. But if you pour a bucket of water onto the ground around the earth spike each day it should be OK.

[Homestar]

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.

Can you elaborate a bit more on these - I've never heard of them?

Also wondering what makes generators unsafe as they are when protected by an RCD? I would have thought if they were inherently dangerous, then industry would not use them... There is no way that the building industry or the ETU would allow them on any site if there was any chance of injury from them. We run over 1,200 machines in our Business unit alone, and over 4,000 around the country, and we have never had an injury caused by one...

I understand how an electric shock can be caused even with a functioning RCD, but that applies for a fixed supply as well as an isolated supply, so we can leave that out of the equation...

Edit - I could only find an article from 2 years ago about these RVD's and a link that no longer exists???

[rovercare]

A generator on its own is a floating supply, not referenced to earth, so it has no potential to earth, meaning it cant kill you between its active supply and earth......active to neutral is still nasty, but an RCD does not protect you in household stuff from that either

If you earth it, or its earthed to its body, its then referenced and there is potential to earth

[rovercare]

Just to add, the earthing system used, as opposed to a "floating" system, due to being such a large system, (the grid), multiple ground faults can become dangerous and hazardous for supply if there was no earthing system

[roverrescue]

soooo
In short is a safety switch a good idea?
Not earthed as per matt?

Ill read that links later

S

[weeds]

One of the electricians at work has a Honda 2 and he has wired in an RCD along with an hour meter permanently onto his machine. He uses it for extended camping on moreton island, the hour meter helps him service it every 100 hours. He clocks up the hours pretty quick.

Although there is an earth tab on the machine there is no need to earth, he doesn't.

He indicated the best reference doc out there is a NSW mining doc on generators. A power boad with RCD is fine

[superquag]

Is this the one ? ...:D

http://www.resources.nsw.gov.au/__data/assets/pdf_file/0008/280754/OUT10-2110-EES-014-Technical-principles-for-the-use-of-stand-alone-generators-_version-2__5_.pdf

And is this useful ?

http://safe-electrical.mdz.com.au/wp-content/uploads/2012/09/SET-Construction-Industry-Paper42.pdf

[drivesafe]

Hi Folks and first off I want to make something very VERY clear, I am NOT an electrician and have no intentions of passing out info relating to 240vac matters.

This is how this new gear came about.

Some 15 or so years ago, a woman was giving her young twins a bath.

She lifted one of the twins from the bath and as she did, she bumped a hair dryer into the bath, electrocuting the other twin.

This horrific event spurred a engineer into developing a safety device that would make such an event a thing of the passed.

15 years later and the IFS is developed and is now patented world wide.

Now to the next problem.

I have nothing to do with domestic ( house ) wiring, I only work with generators and inverters.

Generators and inverters are FLOATING electrical systems and are covered under AS/NZS 3001:2008

These standards specifically cover Electrical installations in Transportable Structures and Vehicles.

NOTE these standards are separate to the normal standards and those used in the Mining Industry.

Now please don’t be offended but most electricians have no idea of how Floating systems have to be installed and by most, I mean the vast majority.

So if you need some 240vac work done on a camper trailer, caravan or a motor home, you may find it vary hard to locate an electrician who actually knows the correct ( read legal ) way to carry out such installations.

And this advice is based on some 20 years of working on motor home and caravans, and dealing with a large number of RV manufacturers.

This following data is for a rough explanation and SHOULD NOT be used as a reference in any way.

In a floating system, if an RCD is used, and installed correctly, you can only use one Class 1 device safely and legally.

In a floating system, if an RVD is fitted, you can use as many Class 1 devices as you can power and they will all be safely protected and be legal.

[weeds]

Hey tim, where do we find any recent info these RVD's..........

I'm happy with the advice I have received from my electrician at work when I wired up my trailer......I couldn't imagine there would be anything too tricky in a mobile install

Do you have example of incorrect installs in mobile equipment....would like to see how mine sits

Cheers

[drivesafe]

Do you have example of incorrect installs in mobile equipment

Hi Kelvin and unfortunately there are plenty of BAD installations done all the time.

A few years back I had an electrician contact me with an electrical problem with his mate’s NEW caravan.

I explained to him I was not an electrician and could not give him any form of electrical advice.

The problem his mate had was that when he bought his NEW caravan home, he set it up in his back yard and, luckily for him, he put down a rubber mat at the door so not to dirty his new caravan.

He plugged his van into the mains and then as he went to climb into his van he got a tingling feeling as he touched the side of the caravan.

The manufacturer had wired the active to earth in revers.

Under the law, the electrician was obligated to notify the authorities and he did so.

About a month later, I got a call from the electrician and he told me the Brisbane caravan manufacturer had to recall 4 other new vans they had wired the same way.

As I posted above, being an electrician, even a VERY good one, does not mean they have ever worked with floating power supplies.

I supply some of the largest RV manufacturers and some years back I got into a real knock down argument ( imagine, me arguing with anyone ) with an electrical engineer, employed by one of the largest motor home manufacturers.

They thought they had done the right thing by employing an electrical engineer but this guy was a joke in the most dangerous way.

I use Hager products and over the years have found them to back their products with very helpful technical support.

On this occasion they were instrumental in putting this horses rear of an engineer in his place.

While the incident is not that important it simply demonstrates that even when large companies try to do it right, they can come unstuck, so the average joe in the street is going to have a hell of a job getting it right.

Now as I have stated, I try to keep out of 240vac threads but two devices have come onto the market that has allowed me to prepare a new kit to resolve a major problem confronting RVers.

The problem, which is getting worse, is how to run a 3 way fridge and charge house batteries at the same time.

I have never been a fan of DC/DC devices because of their high set up price for such a small potential gain ( if any ), and they do not address the 3 way fridge problem.

I was told about the proposed introduction of the RVD a year or so back and this device would make a safe use of two other devices in a set up that would address the 3 way fridge/house battery charging in one go but would also have other uses for the devices when not powering the fridge and charging batteries while on the move.

This is the only reason I have made it my business to study and test the RVDs in both inverters and generators.

[p38arover]

I'm surprised no one has already posted this answer to your question. It's really quite obvious!

https://www.aulro.com/afvb/images/imported/2012/10/160.jpg

[slug_burner]

Hi Kelvin and unfortunately there are plenty of BAD installations done all the time.

A few years back I had an electrician contact me with an electrical problem with his mate’s NEW caravan.

I explained to him I was not an electrician and could not give him any form of electrical advice.

The problem his mate had was that when he bought his NEW caravan home, he set it up in his back yard and, luckily for him, he put down a rubber mat at the door so not to dirty his new caravan.

He plugged his van into the mains and then as he went to climb into his van he got a tingling feeling as he touched the side of the caravan.

The manufacturer had wired the active to earth in revers.

Under the law, the electrician was obligated to notify the authorities and he did so.

About a month later, I got a call from the electrician and he told me the Brisbane caravan manufacturer had to recall 4 other new vans they had wired the same way.

As I posted above, being an electrician, even a VERY good one, does not mean they have ever worked with floating power supplies.

I supply some of the largest RV manufacturers and some years back I got into a real knock down argument ( imagine, me arguing with anyone ) with an electrical engineer, employed by one of the largest motor home manufacturers.

They thought they had done the right thing by employing an electrical engineer but this guy was a joke in the most dangerous way.

I use Hager products and over the years have found them to back their products with very helpful technical support.

On this occasion they were instrumental in putting this horses rear of an engineer in his place.

While the incident is not that important it simply demonstrates that even when large companies try to do it right, they can come unstuck, so the average joe in the street is going to have a hell of a job getting it right.

Now as I have stated, I try to keep out of 240vac threads but two devices have come onto the market that has allowed me to prepare a new kit to resolve a major problem confronting RVers.

The problem, which is getting worse, is how to run a 3 way fridge and charge house batteries at the same time.

I have never been a fan of DC/DC devices because of their high set up price for such a small potential gain ( if any ), and they do not address the 3 way fridge problem.

I was told about the proposed introduction of the RVD a year or so back and this device would make a safe use of two other devices in a set up that would address the 3 way fridge/house battery charging in one go but would also have other uses for the devices when not powering the fridge and charging batteries while on the move.

This is the only reason I have made it my business to study and test the RVDs in both inverters and generators.

The problem would not have become apparent if they had plugged into a fully floating supply like a stand alone generator. It was the house connection to earth that gave your caravaner the tingles (in combination with the poorly wired caravan of course).