Generators/Caravans/Rcd`s

Submitted: Thursday, Jan 10, 2013 at 16:54
ThreadID: 99910 Views:6732 Replies:7 FollowUps:7
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Having just purchased a caravan that we will use for free camping for a fair period of time so that I want to buy a generator for wet days.


There was a good deal of discussion in a couple of posts last year about the safety of using a generator with a caravan.


I don`t want to re open the subject , as there were a few differing opinions, I only want to say that I respect Olcoolone`s opinion on the subject, so bringing any thing up re this past discussion is not sought by me.

Given that the caravan`s Rcd will not work when powered by a generator, I have this question. `If I use an Ampfibian immediately after the generator, which has a built in Rcd will this work instead`? Obviously only on the 10amp plug on a dual 10/15 amp plugged generator.

Olcoolone , if you see this I would be grateful for your comments.

Another alternative is to use a Genquip G3300 generator which can be fitted with an optional Rcd ( $200.00) Would this do instead?

The bottom line is that I wan`t to be safe if I use a generator.

Yes --- I will be getting a solar system, questions about this later.

Regards G.T.
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Reply By: mrtiggs112 - Thursday, Jan 10, 2013 at 18:09

Thursday, Jan 10, 2013 at 18:09
The caravan would need to be "earthed" for an RCD (safety switch) to work.
Circuit breakers are only to protect the cabling and equipment from over loading.
Cheers Geoff
AnswerID: 502159

Follow Up By: Dennis Ellery - Thursday, Jan 10, 2013 at 19:06

Thursday, Jan 10, 2013 at 19:06
"The caravan would need to be "earthed" for an RCD (safety switch) to work"
That statement is vague and misleading
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Reply By: pop2jocem - Thursday, Jan 10, 2013 at 18:45

Thursday, Jan 10, 2013 at 18:45
My understanding is that in Australia our houses are wired Multiple Earth Neutral (MEN).
The neutral is earthed at the point of generation, our homes and AFAIK along the transmission system. In effect the earth and neutral have the same potential. If power has found a path to earth other than by the designed conductor the RCD senses this and interrupts the supply.
A caravan and generator are an isolated supply consumer system, no earth involved so that you would need come into contact with both active and neutral to receive a shock.

DISCLAIMER

Now don't just take my word for that but that is how it was explained to me and from my understanding an RCD is not effective in this scenario. Others may be able to put up a better explanation.

Cheers
Pop
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Follow Up By: Dennis Ellery - Thursday, Jan 10, 2013 at 19:03

Thursday, Jan 10, 2013 at 19:03
Without getting too technical – that’s a pretty good summary.
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Follow Up By: Ross M - Thursday, Jan 10, 2013 at 20:14

Thursday, Jan 10, 2013 at 20:14
I agree that theory is correct because of the insulation inbuilt factor and an RCD won't operate but can be in circuit anyway and everything will work as normal.

However, having had a shock from this supposed "safe" system because of ambient dust and humidity carried current back to the frame and obviously the core, of the generating device, it possibly would have triggered the RCD if it had been in the circuit. Purely because there suddenly WAS another path for the voltage, unseen and not usual, but there all the same.

Humidity and dust are things which do occur in Australia. Darwin springs to mind.
Insulators on power poles don't carry any current except when they do. ie dirt and moisture. Talk to power companies about it.

I have had bites of 240v from using other peoples 240 appliances which were dirty and moist or conductive across the plastic inside and when used you find out that dirt extends to the hand grip too. It activates and RCD as well.

My belief is: if you have an RCD use it, you won't make it worse.
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Follow Up By: Member - Frank P (NSW) - Thursday, Jan 10, 2013 at 23:49

Thursday, Jan 10, 2013 at 23:49
The Honda EU20I genny has an earth point, as do many others.

Would an RCD in a van provide better protection if the generator was earthed with a decent spike (I made one about 300mm long - is that good enough?) and the caravan earthed via one of the chains and a spike.

No-one that I know does this. Should they?

Cheers
FrankP

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Reply By: Allan B (Member, SunCoast) - Friday, Jan 11, 2013 at 00:52

Friday, Jan 11, 2013 at 00:52
.
As GT has said, earlier discussions on this subject raised differing opinions, most of them by persons without appropriate electrical qualifications, so I am not reopening that 'can-of-worms'.

I will say only that using a portable RCD at the generator outlet can provide protection in some, but not all, circumstances. So it may afford a false sense of security.

On the subject of earthing the generator frame using the provided 'Earth' connection or any other connection to the metal body or frame, I would explain as follows:
The electrical windings and wiring of small portable generators have no connection to the frame, i.e. they are isolated or 'fully floating' and designated as an 'IT' system. Only the earth pin of the outlet socket is connected to the generator frame. Connecting the generator frame to an earth stake would serve no purpose so long as the windings isolation is preserved, i.e. there is no insulation failure of the windings or wiring within the generator. Accordingly, the electrical regulations neither require nor recommend an earth stake.

To reliably incorporate an RCD into the circuit it is necessary to connect one end of the generator windings to the body of the generator thus creating an earthed neutral or 'TT' system. It is not designated an MEN system as the neutral is not earthed at 'multiple' locations but is effectively the same. It is also necessary to add an effective earth stake connected to the generator frame and the neutral conductor. Note that this stake must be "effective" and accordingly at least 1.4m long..... a 300mm tent peg will not suffice.

The "bottom line" is to avoid electric shock when using a portable generator with appliances and caravans, use only double-insulated appliances and maintain the generator, connecting cables, and the appliances in good condition, keeping all dry at all times.

Cheers
Allan

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Follow Up By: Dennis Ellery - Friday, Jan 11, 2013 at 10:29

Friday, Jan 11, 2013 at 10:29
Hi Allan
The normal RCD used with a non-earthed neutral system offers virtually no protection against electrocution. I would be interested in what situations you thought it would offer any protection?
Regards Dennis
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Follow Up By: Allan B (Member, SunCoast) - Friday, Jan 11, 2013 at 10:51

Friday, Jan 11, 2013 at 10:51
.
Hi Dennis,


The only circumstance where such an RCD would trip is where a fault to the generator body or frame occurred on the supply side of the RCD effectively creating a 'TT' or 'earthed neutral system', then subsequently a person was to unintentionally create a body path between the opposite live conductor ('active') and earth. This scenario could well be caused where the electrical equipment (generator and appliance) had become wet. Granted, not perhaps a common situation and personally I would prefer to avoid operation such wet electrical equipment rather than rely on an RCD for protection.


And Dennis, thanks for requesting an explanation rather than repudiating the proposition as some might do.

Cheers
Allan

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Follow Up By: Dennis Ellery - Friday, Jan 11, 2013 at 11:55

Friday, Jan 11, 2013 at 11:55
Thanks for the example – in most cases electrical faults occur with plug in portable devices, making the RCD ineffective on small gensets.
Regards Dennis
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Reply By: Member - G.T. - Saturday, Jan 12, 2013 at 09:22

Saturday, Jan 12, 2013 at 09:22
Thanks everyone for your input. Obviously one has to be very careful when using a generator with a caravan. Regards G.T.
AnswerID: 502326

Reply By: Nomadic Navara - Saturday, Jan 12, 2013 at 23:39

Saturday, Jan 12, 2013 at 23:39
There has been some confusing and conflicting info about earthing caravans and generators. The Australian standards say don't do it. End of story.

Quote "Given that the caravan`s Rcd will not work when powered by a generator, I have this question. `If I use an Ampfibian immediately after the generator, which has a built in Rcd will this work instead`? Obviously only on the 10amp plug on a dual 10/15 amp plugged generator."

If the RCD in the van will not do anything for protection when you are not hooked up to the mains then a second RCD will not add any protection. They both work the same way.

Quote "Another alternative is to use a Genquip G3300 generator which can be fitted with an optional Rcd ( $200.00) Would this do instead?"

That is the only way you will get protection from a RCD.
PeterD
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AnswerID: 502399

Reply By: oldtrack123 - Sunday, Jan 13, 2013 at 00:03

Sunday, Jan 13, 2013 at 00:03
HI
A lot of conflicting advise here, on the subject of generators & RCds
SO here are the FACTS:
[1]your Van /camper RCD will not function with a generator plugged into the van power inlet
It cannot as the the standard small portable generators allowed to be sold in cannot ,off the shelf ,have the suitable internal connections

[2]For a portable generator to have RCD protection ,it must have a PERMANENTLY fitted& correctly connected RCD

[3] NO plug in RCD can work
that includes The Ampfibian , Arlec, Clipsal & similar RCD protected power boards[EPODS]
[4]The standard generator may be PERMANENTLY fixed & wired into the van with suitable changeover switching that allows the van RCD to be fully operation on both mains & generator
[5]The van /camper ,etc should not have any other form of earthing except the earthing within the extension lead /connecting lead
DO NOT USE AN EARTH STAKE, do not deliberately connect the frame of the van /camper, or generator to the general mass of earth or an other known earth[building, water pipe etc]
This applies in Aus, no matter what the makers manual may say!!!

A new device," RVD combo",can be used instead of the VAN RCD. It overs superior protection with any source plugged into the Van power inlet
It MUST BE BE fitted & wired by a licensed electrician

for more info contact
'Powerstream RV'

or "Traxide industries "

Peter
AnswerID: 502400

Reply By: Bob Y. - Qld - Sunday, Jan 13, 2013 at 15:25

Sunday, Jan 13, 2013 at 15:25
G.T.

Have used portable generators, and engine powered welders all my working life, and never had a "dangerous" incident. Also had 6 years in a 'van, providing our own power with no mishaps.

As long as any appliances used are kept dry(and dust-free) then all should be good. If you did decide to use an earth stake off your 'van then it should be hammered well into the ground, and be attached to the 'van with cable, not chain, as someone suggested. The sink outlet is an ideal spot as it provides good, damp earthing position, in what might otherwise be dry soil.

With extension leads, if you happen to join 2 leads, as well as waterproofing the joining plug/socket, elevate the assembly so it is not sitting on the ground, in any pools of water. Speaking from experience here :-)

Did fit an ELB(forerunner of RCD's, I think???) to our generator, and it worked on a number of occasions, not the least of which was when it shut the power off, as a gas leak on the fridge melted the J-box immediately above the leak. We reckon this saved us from losing the 'van.

Bob.

Seen it all, Done it all.
Can't remember most of it.

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