Hi there, is there such a switch/terminal that can be used to switch 240v input between mains and the inverter.

I thought of a battery 3 way switch, but no one is game enough to say "yes you can" ...any ideas?

Peter

Thanks for that....good advice

All too difficult,....I have read that the inverter is a floating 240v system and should not be earthed. therefore....no problem ill just run a power point from the appliance i want to run back to the inverter..

all good

thanks

Peter

Peter and Jian wrote:

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All too difficult,....I have read that the inverter is a floating 240v system and should not be earthed. therefore....no problem ill just run a power point from the appliance i want to run back to the inverter..

all good

 

thanks

 

Peter

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It is not so hard.

It is quite safe to run a single appliance from the inverter, but not more than one at a time (unless they are double insulated). Exactly the same applies to a generator.

Yes, they are "floating" power supplies.

Cheers,

Peter

Peter_n_Margaret wrote:

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It is quite safe to run a single appliance from the inverter, but not more than one at a time (unless they are double insulated).

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 Why do you say that Peter?

Mike Harding wrote:

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Peter_n_Margaret wrote:

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It is quite safe to run a single appliance from the inverter, but not more than one at a time (unless they are double insulated).

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 Why do you say that Peter?

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 Because with an isolated power supply, the RCD will be ineffective which means that if there is a fault with 2 separate appliances and you happen to touch both then you could be electrocuted and the RCD will not protect you. An RVD operates differently and provides that protection. This risk does not occur if the appliances are double insulated.

Cheers,

Peter

This might give you an idea of what it should look like.
Mine switches between 3 sources mains, generator or inverter.
Done professionally by a tradesman who knew the regs.

Cheers,

Peter_n_Margaret wrote:

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Yes you can.
You need to consult a licensed electrician who is familiar with AS3001, "Transportable buildings".
A 3 way battery switch is NOT suitable.
Anyone who tries to tell you how to do it on a public forum could leave themselves open to very serious charges if/when it goes wrong.

Cheers,
Peter

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 DITTO 

Peter and Jian wrote:

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Hi there, is there such a switch/terminal that can be used to switch 240v input between mains and the inverter.

I thought of a battery 3 way switch, but no one is game enough to say "yes you can" ...any ideas?

 

Peter

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 A battery 3way switch should NEVER be used on 240V !!!

Thanks very much... nice to know it is possible and my thought process was on track.

peter

Peter_n_Margaret wrote:

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Mike Harding wrote:

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Peter_n_Margaret wrote:

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It is quite safe to run a single appliance from the inverter, but not more than one at a time (unless they are double insulated).

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 Why do you say that Peter?

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 Because with an isolated power supply, the RCD will be ineffective which means that if there is a fault with 2 separate appliances and you happen to touch both then you could be electrocuted and the RCD will not protect you. An RVD operates differently and provides that protection. This risk does not occur if the appliances are double insulated.

Cheers,

Peter

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 Yes!!

Fully agree !

The safety recommendation is:

NEVER connect more than ONE class 1 device to an" electrically  isolated power supply" [inverter or generator]

Multiple class   2 ,with one class 1 can be safely used  ,with very low risk of shocks to earth

 class 1 shall have a 3 pin plug Class 2 only require a 2 pin plugs

Peter_n_Margaret wrote:

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Mike Harding wrote:

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Peter_n_Margaret wrote:

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It is quite safe to run a single appliance from the inverter, but not more than one at a time (unless they are double insulated).

---

 Why do you say that Peter?

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 Because with an isolated power supply, the RCD will be ineffective which means that if there is a fault with 2 separate appliances and you happen to touch both then you could be electrocuted and the RCD will not protect you. An RVD operates differently and provides that protection. This risk does not occur if the appliances are double insulated.

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A bit of a long bow I think.

This would require appliance number one to develop a fault which causes its chassis to become connected to active without tripping an overcurrent breaker and remain in that state indefinitely and, at some future point, appliance number two to develop a fault which caused its neutral to become connected to chassis without tripping a breaker and for both faulty appliances to be connected at the same time and then for a user to simultaneously touch both appliances....?

It is theoretically possible but I suggest one has a greater chance of being struck by lightning while in an underground mine, standing in a bowl of custard, and singing Advance Australia Fair to the tune of Three Blind Mince.

Mike, consider this, all houses and systems that have an operative RCD have one leg of an otherwise floating system tied to the earth wire and therefore the conductive parts are already in what you call a fault condition. By linking one leg of the 240v to earth a floating system becomes an active/neutral system. This doesn't trip an over current breaker and no one feels an electric shock because only one leg of the AC is exposed. This connection is made before the RCD so it can sense another connection of the neutral to the earth after the RCD and trip the breaker.
In a floating system neither leg is tied to the earth wire, so there is just line 1 and line 2. Say a fault occurs inside the walls of the RV and either line 1 or line 2 come into contact with part of the conductive body work. No one will feel it and nothing in an RCD will sense it. Now all that is required is a fault in an appliance that makes the conductive area live to the other leg of the floating system. Same deal, no one would feel anything because again, it is only one leg and the RCD won't sense it. Now the person holding the faulty appliance touches the body. The body is connected to say line 1, the appliance body to line 2. The RCD still doesn't sense a fault and as long as the current passing through person now in contact with both line 1 and line 2 doesn't exceed the 16 amps limit of the over current circuit breaker, the RCD will just sense the person is another appliance with possibly fatal consequences.
Many of the better quality *UPS style inverters now have an auto switching earth/neutral link and built in RCD so the 240vac is always protected by an RCD.

T1 Terry

* uninterrupted power supply, switches to mains when available and back to inverter when mains power is lost

Bagmaker wrote:

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you also need to isolate the external input plug point from 240v AC inverter feed.
wouldnt want little johnny fiddling with that whilst the rig is battery powered

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 That is covered IF the inverter is  being used correctly, OR is correctly PERMANENTLY wired in. accordance with the standards & as covered by the Electrical regulations of EVERY state carried out by a licensed person familiar with the appropriate Standard 

That is why the inverter or generator should only be used in accordance with the AUs Standards  & Safety recommendations

All should understand that even the smallest 240V inverter can KILL

Peter_n_Margaret wrote:

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Mike Harding wrote:

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Peter_n_Margaret wrote:

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It is quite safe to run a single appliance from the inverter, but not more than one at a time (unless they are double insulated).

---

 Why do you say that Peter?

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 Because with an isolated power supply, the RCD will be ineffective which means that if there is a fault with 2 separate appliances and you happen to touch both then you could be electrocuted and the RCD will not protect you. An RVD operates differently and provides that protection. This risk does not occur if the appliances are double insulated.

Cheers,

Peter

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 Peter is TOTALLY correct

The potential risks of electrocution when connecting more than ONE class 1  device, to an electrically isolated source has long been recognized

The safety recommendation for many many years has been & still is:

DO NOT CONNECT MORE THAN ONE Class1 device @ any time.

One class 1 &/or multiple class 2 [ double insulated to Standards ]approved can be connected with a high degree of safety from shocks to "earth"

Shocks & electrocution  actually occurred before this recommendation came in.

It was introducd many years ago

T1 Terry wrote:

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Something to keep in mind, the caravan or motor home has a connection to the conductive material to the green and yellow earth cable and that makes it part of the earth circuit and therefore considered a class 1 appliance because the conductive area is connected to the earth cable.
Now the bit that needs to be explained by those that like to stipulate the inverter body must be connected to the chassis of the vehicle, if the inverter body is connected to the vehicle body conductive areas via a common link to the earth cable, is any class one appliance now safe to be plugged into the inverter? After all, the now common earth link between the inverter and the conductive area of the vehicle makes the vehicle the first class 1 appliance connected to the inverter, any thing else plugged in to the inverter would now be the second appliance.

T1 Terry

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 I do not quite understand what you are saying

An approved FULLY isolated source [inverter or generator] has to meet very strict insulation "Standards "requireiments  regarding both insulation quality /longevity etc   between the high voltage & lower voltage sides & the higher voltage to "earth/frame"

Who stipulates that the portable inverter or generator body must be "earthed"??

The fact is that the regulations clearly say that such should not be deliberately  '"earthed "to the general mass of earth

But there is a very obvious need for  the metal frame of a generator or If the inverter has such ,for a good electrical bond  between earthed conductive surfaces of the van  back to the generator frame' as anyone who fully understands the risks would see

Correct "earthing" is a lot more complicated than many think.

More "Earths " is not always better

Incorrect earthing can have nasty outcomes 

It can even increase the risks of shocks & fires

Sorry, can't reply at present... too busy looking for a bowl of custard and the musical score for Three Blind Mice.

Honestly! You people need to get out more....

T1 Terry wrote:

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I'll try to draw the path. If the inverter body is connected to the vehicle chassis and so is the 240vac system earth wire connected to the chassis, effectively the inverter body is connected to the AC earth circuit. As far as the inverter or generator meeting very high insulation standards, I'm guessing any 240vac appliance must meet the same standards. If we are considering the possibility of an appliance having a fault to the conductive body then how can we ignore the possibility of the generator or inverter suffering the same problem?

T1 Terry

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 Hi Terry

You  should get ALL the appropriate standards rather than make assumptions on a public forum

Totally different Standards apply to Fully isolated supply sources ,compared to non isolated supply sources

Just as totally different Standards apply to double insulated devices compared  to single  insulated devices ,ie those which require an earth connection

Are you again suggesting that you are wiser than all those highly qualified people who have input into the electrical Standards

Of course we can all dream up extreme situations where problems could occur .

NOTHING is FOOL proof!!

The safest way is to not have portable [plug & socket connected] generators or inverters or appliances, but to have them permanently wired in  in accordance with the Standards. 

But that is not always practical. 

 The next step will be for manufacturers to have to fit permanent  earth leakage detection into the isolated supplies[ along the lines of a RVD] so that the source shuts down even for loss of isolation within the source

I may not see that as a Standards requirement, but it will not be long

In fact some small portable generators  makers have  already gone that far.

Ahead  of the pack & the Standards

Something along the original concept of Ian's  RVD   [when he first raised the idea  & was seeking comments, from such as myself], [not switching the load,but deactivating   the control system]

Relatively easy with inverter generators & inverters

-- Edited by oldtrack123 on Friday 20th of April 2018 10:38:47 PM

T1 Terry wrote:

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Sorry Peter, from now on I'll add a note to all appliances and inverters that I fit that it is against the standards to have a fault to the conductive part of the body and they should not even consider doing such a thing. Not sure how I should word it, maybe "Thou shall not fault to and conductive surface lest though suffer the wrath of Peter Oldtrack123 and the fury of the standards police" would that cover it?
But then that would negate you rule of only one class 1 appliance in a floating supply because all appliances would no better that to have a fault to earth :roll:

T1 Terry

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 Well I read & reread above & it still make  no sense!!

You would obviously have great difficulty in understanding the whole 700 odd pages of As/NZS 3000

The Standards &rules make very good sense IF you can retain more than one line @ a time.  

"Fitting appliances & inverters ""?

Are YOU doing  Licensed Electrical Work ?????.

Regarding Standards ,from a post on another forum

"A bit off topic , but last night I had a run through on an Australian electrical forum that I am a member of.

As usual ,I was astounded by some of the questions & comments made by some licensed "Electricians ?
Mainly in regard to the new Standards which give considerably more leeway on subjects like circuit loading ie more onus on the electrician to understand the intent of the rules 
That means using their brains & teck knowledge  
I am afraid at the obvious LACK of some basic knowledge & understanding exhibited from some "electricians"   

Terry posted

"I'll try to draw the path.

[a]If the inverter body is connected to the vehicle chassis and so is the 240vac system earth wire connected to the chassis, effectively the inverter body is connected to the AC earth circuit.

As far as the inverter or generator meeting very high insulation standards, I'm guessing any 240vac appliance must meet the same standards. If we are considering the possibility of an appliance having a fault to the conductive body then how can we ignore the possibility of the generator or inverter suffering the same problem?"

I will have another go 

[a] If it is an approved fully isolated the inverter, the  Standards require an extremely  high level of electrical . isolation of the 240V  part from the inverter body. AND all the 12V 

It does not matter that the inverter body or generator frame is in contact  or connected to with the vehicle earthing system .

In fact it is a  Shall requirement,& occurs via the Earth cable in the connecting lead. AND THAT is the only "earth" connection required. No connection to mother earth [ NO earth stake]

   No connection to electrically earthed structures

It is not just a SHALL requirement, but a basic requirement for safety purposes & full correct operation of the RCD [ if fitted to the generator ]under virtually all foreseeable  circumstances

Perhaps a little clue for you to  consider  "Shunt earth leakage currents"

Perhaps you are thinking about the inverters which have been banned for YEARS  in Aus ,that were not fully isolated & led to many accidents including deaths???

[B]No ,There are substantially different requirements ,substantially different STANDARDS  for fully isolated sources such as portable generators & inverter. as compared to generall electrical appliances etc

 Perhaps you do not really know the full extent of ALL the  Electrical Standards.?????

There are different Standard for:

large portable  fixed wired generators[ emergency supply units]

for large inverters permanently wired in 

for ups

 for inverter chargers

Of course  depending on what your risk assessment is we could call for triple or quad or even higher levels of isolation. but @ this stage it seems there is no valid reason to go that far

For Instants there are even further requirements covered by  specific Standards  for ALL electrical equipment used in patient areas Wards etc in hospitals

How far do you want to go?????

You people need to get out more.

Mike Harding wrote:

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You people need to get out more.

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 You, have previously made the same comment .