Inverter help

Thanks Fred

Fred, the trouble with "common sense" is that it is not very common.

Hi Allan
"""If using an appliance which is not double-insulated, or if using an appliance with an extension cord outside the vehicle, safety can be improved by incorporating an RCD (Safety Switch). These can be purchased in the form of a short plug-in extension lead."""


Sorry mate, but the RCd ,in that case, will not function as earth fault detector

The inverter has no & should not have an EN link
For safety only have one class1 devise [one that has 3pin plug] plugged in @ atime.
If plugged into van etc ,van RCd will also offer no protection & you then have multiple class one devises connected ,including the van itself

As /NZs Standards3001 : 2008 has specific rules for vans /motor homes etc ,To be used with as 3000.

Hi Oldtrack, "Sorry mate, but the RCd ,in that case, will not function as earth fault detector".

1. The in-cord RCD I described certainly will operate correctly when used with an inverter, or any other supply with no MEN link. It operates entirely by detecting any imbalance between the two supply conductors and has no reference to earth. It does not "function as an earth fault detector". (That's an ELCB) An RCD presumes that any current which goes out on one line and does not return on the other must be returning by another path, possibly via a person's body, and accordingly disconnects the supply. Its very purpose is to provide a safety component without reliance on,or reference to, an earthing system.

2. Referring to "Class 1" or Class 2 devices will only confuse those who are not familiar and competent with the subject. And a "3-pin plug does not define Class 1, a Class 2 equipment may also be fitted with a 3-pin plug.

3. As you might expect, I am well aware of specific standards for vans etc which is why I avoided advice and recommended such work be carried out by a licensed electrician.

I question whether debating these matters on a forum is in the best interests of the public who are likely to become even more confused. I could go on in depth with engineering explanation but here is not the appropriate venue.

Hi Allan

Sorry but I believe this is the place for incorrect info to be corrected.
#1Before you continue I think you need to do a little research on RCD & ElCbs THEY ARE THE SAME DEVISE as are SAFETY SWITCHS.

Their operation is quite simple ,they measure the out of balance in current between active & neutral due to current flowing back to source via earth

They do not protect a person who connects across active & neutral with a fully isolated power source

THEY CAN only operate with A EN or MEN system NOT with a fully isolated power source wether that be inverter OR genny.

NO one should attempt such modifications to inverters or gennys unless they are fully qualified & KNOW WHAT. IS ACTUALLY REQUIRED.

Some gennys & inverters are not suitable.
Under no circumstance interfere with any 240 v wiring or attempt to make additional earth connections ,

Connecting the metal FRAME of the inverter to the vehicle chassis may reduce radio /tv interference

#2 Yes i agree that some/many class 2 devises may be fitted with a 3pin plug BUT ALL CLASS 1 ARE fitted with a 3pin plug
I could have said, any devise that should have an earth connectionEtc BUT how would many know the answer to that.
BUT by assuming if it has a three plug& should have an earth connection they are erring on the safe side
I totally agree ,that all 240v work should be carried by Certified & QUALIFIED elecrtricians ,familar with As 3001

Alright Oldtrack, If you insist but it could get ugly.

Firstly I gather that you have some involvement in the electrical industry, possibly an electrician? I too have been involved in the electrical industry as an electrical engineer, for a lifetime, multi qualified and widely experienced. So I claim that mine is bigger than yours!

Your suggestion that I do a "little research on RCD's and ELCB's" is amusing to say the least. I was working with ELCB's long before RCD's were developed.
They are NOT the same thing although the electrical industry initially erroneously referred to the new RCD's as ELCB's and many such as you still do so. The term "Safety Switch" is a popular term for an RCD but it is not a engineering or definitive term.

An ELCB (Earth Leakage Circuit Breaker) was exactly that.... Earth leakage. Prior to 1980 and the introduction of the MEN (Multiple Earthed Neutral) system, protection from electric shock from appliances was managed by the Direct Earthing System whereby the installation earth wire was connected to the town reticulated water pipe. In locations where there was no reticulated water mains Voltage operated Earth Leakage Circuit Breakers were employed. The installation used an insulated earth wire which connected to the coil of the ELCB with the other side of the coil connected to an earth stake. The neutral conductor of the supply mains was connected to an earth grid at the point of supply, typically the supply transformer. In the event of insulation failure and leakage from the active conductor to the earth wire, a current would pass through the ELCB coil and cause it to trip thus isolating the supply from the installation. The ELCB then needed to be manually reset. The system suffered from a number of problems but was the best that could be provided at the time.

The introduction of the MEN system rendered the ELCB redundant and provided electrical installations with a means of directing earth fault currents back to the supply source via the neutral line and not through the water pipes, a definite improvement especially where no water pipes were available. The subsequent development of the RCD added a great improvement to electrical safety but unfortunately their introduction was somewhat piecemeal and they were called by several different names including ELCB's as they performed a similar task. Eventually the "official" name was assigned as Residual Current Devices (RCD's) and that is all they should now be called. The bad habits of the industry however are not dying easily and many including even suppliers still refer to them as ELCB's but incorrectly.

AS/NZS 3000 Wiring Rules uses ONLY the term RCD. The only single reference in that standard to ELCB is in clause 5.1.4(c) where reference is made to "former direct earthing or voltage operated ELCB systems".

Earth leakage relays continue to be used in certain industrial installations and in particular electricity distribution equipment such as large transformers to provide alarms and trips in the event of earth leakage currents.

So Oldtrack, do you still think I need to "do a little research" on this subject? I damn near wrote the book on it! Don't try to teach your grandmother to suck eggs!

And I repeat, an RCD will work satisfactorily and properly on an isolated power source. It does not need a direct earth or MEN system. If you understood the device and how it operates you would realise that. If the current being delivered by the "active" conductor does not fully return by the "neutral" conductor it must be getting back by another path possibly your body and the RCD will detect this and interrupt the supply possibly saving your life. Just because you have not experienced such installations does not mean that they do not exist. They are an excellent life-saving safety device and I would not operate an electrical installation, either fixed mains fed, or portable inverter or generator fed, without a RCD with the exception maybe of inverter and double insulated appliance within the vehicle.

OK?

Hi Allan
Yes it going to get ugly.

#1::Firstly I gather that you have some involvement in the electrical industry, possibly an electrician? I too have been involved in the electrical industry as an electrical engineer, for a lifetime, multi qualified and widely experienced. So I claim that mine is bigger than yours!

#2:Your suggestion that I do a "little research on RCD's and ELCB's" is amusing to say the least. I was working with ELCB's long before RCD's were developed.
They are NOT the same thing although the electrical industry initially erroneously referred to the new RCD's as ELCB's and many such as you still do so.
#3"The term "Safety Switch" is a popular term for an RCD but it is not a engineering or definitive term.

#4:An ELCB (Earth Leakage Circuit Breaker) was exactly that.... Earth leakage. Prior to 1980 and the introduction of the MEN (Multiple Earthed Neutral) system, protection from electric shock from appliances was managed by the Direct Earthing System whereby the installation earth wire was connected to the town reticulated water pipe. In locations where there was no reticulated water mains Voltage operated Earth Leakage Circuit Breakers were employed.

#5:The installation used an insulated earth wire which connected to the coil of the ELCB with the other side of the coil connected to an earth stake. The neutral conductor of the supply mains was connected to an earth grid at the point of supply, typically the supply transformer.

#6In the event of insulation failure and leakage from the active conductor to the earth wire, a current would pass through the ELCB coil and cause it to trip thus isolating the supply from the installation. The ELCB then needed to be manually reset. The system suffered from a number of problems but was the best that could be provided at the time.

#7:The introduction of the MEN system rendered the ELCB redundant and provided electrical installations with a means of directing earth fault currents back to the supply source via the neutral line and not through the water pipes, a definite improvement especially where no water pipes were available. The subsequent development of the RCD added a great improvement to electrical safety but unfortunately their introduction was somewhat piecemeal and they were called by several different names including ELCB's as they performed a similar task. Eventually the "official" name was assigned as Residual Current Devices (RCD's) and that is all they should now be called. The bad habits of the industry however are not dying easily and many including even suppliers still refer to them as ELCB's but incorrectly.

AS/NZS 3000 Wiring Rules uses ONLY the term RCD. The only single reference in that standard to ELCB is in clause 5.1.4(c) where reference is made to "former direct earthing or voltage operated ELCB systems".

#8Earth leakage relays continue to be used in certain industrial installations and in particular electricity distribution equipment such as large transformers to provide alarms and trips in the event of earth leakage currents.

#9:So Oldtrack, do you still think I need to "do a little research" on this subject?:
I damn near wrote the book on it! Don't try to teach your grandmother to suck eggs!

#10And I repeat, an RCD will work satisfactorily and properly on an isolated power source. It does not need a direct earth or MEN system. If you understood the device and how it operates you would realise that. If the current being delivered by the "active" conductor does not fully return by the "neutral" conductor it must be getting back by another path possibly your body and the RCD will detect this and interrupt the supply possibly saving your life. Just because you have not experienced such installations does not mean that they do not exist. They are an excellent life-saving safety device and I would not operate an electrical installation, either fixed mains fed, or portable inverter or generator fed, without a RCD with the exception maybe of inverter and double insulated appliance within the vehicle. "



You sure have problems with your teminology.
From reading your post YOU are obviously referring to RVDs ,"RESIDUAL VOLTAGE DEVICES" that Do NOT & CANNOT work with an EN /MEN system
Thet are only now coming onto the market for general use WITH FULLY ISOLATED POWER SUPPLIESsuch as gennys & inverters

So here goes

#1
well i will leave others to judge by the end of this post
#2 Perhaps power suppliers teminology is differrant but I believe you were working with RVDs ,which detect a leakage between either line to earth & trip & as you say had to be manually reset
Throught the trade in AUS they have been referred to as ELCBS then &now RCDs
But when 1st on market, in late 50s ,early 60s from memory, they were called "core balance cb" The name says it all "Core balance" equal currents in active & neutral .
They had no direct connection to earth .They did not carry earth current.
#3
I agree the term "safety switch" which is creeping in & is what lay people know them as, is not a good or acceptable term my reason for saying this is it may lead to a false belief that one isc completly protected from elecric shock
#4
I think I've explained that in#3 But I'll just add a bit.
Brisbane had 2 suppliers, in thelate40s /early 50s, one used direct earthing ,the other used MEN
You had be sure whose area you were in as they tended to intertwine.
ELCBS were not in use .
The 1st ELCBS/CORE balance cbs as stated above did not come on to the market till about the late 50s early 60s.
#5
I think I have explained that too but again end users did not have an elcb monitoring earth currents
#6
At the suppliers lines ,yes but not in the customers premises & i believe the correct term was RVD
#7
to save repetition read the above
#8
RVDs Are now coming onto the market for use with FULLY isolated power sources such as gennys & inveters
#9
Better get to grandma & see if she can teach you how to suck eggs
#10
What can I say except you have no idea of how a RCD works.
Please, if you cannot understand what i have posted sit down & draw it out & see if you can find away for the curent to get back to the power source without an EN link
I repeat THEY monitor current flowing in active & neutral THEY have no direct connection with earth
THEY detect the out of balance currents which can only return to the source via an EN bond.
THEY simply cannot work on a fully isolated system.
Your last statement is a real frightener, RCDs offer no protection for direct contact between Active & neutral
But just to make you feel better you are not the only one who has made similar wrong statements. & believe RCDs can operate without the bond /link
I strongly you do do a bit of research ON RCDs, RVDs

I hope any one reading this now understands it is something that only a licenced & QUALIFIED[ conversant with ALL the rquirement of the regs] electrician should carry out see my earlier post.

Hi All
Unfortunately I can not edit my post
But to help the first 10 dot pointed comments are Allan's the 2nd set are my replies

Hi Lyndon,
I hope thats cleared up your query - or would you like the gentlemen to go into more detail.

OK Oldtrack, I just went out to the workshop and connected a stock standard unmodified inverter to a 12v battery with the 240v output connected to an RCD. Hooked a lamp to one side of the 240v and the other to the earth pin of the inverter outlet socket --- IT TRIPPED. Repeated with lamp connection to metal body of inverter --- IT TRIPPED. Clearly, not all inverters are fully isolated even if you consider that they should be.

I there anything else I can do for you?

(Sorry Lyndon & Dennis, that was my final shot.)

Hi Allan
Thanks for that little bit of info
It shows how little you know about the real world
That type of inverter is banned on all building,construction ,mining sites in AUS Due a number of deaths when using them & have been removed from the market
Without an INBUILT RCD they are a death trap.!!
You may also find a connection between the 240v side & the 12v side .
This makes them even more dangerous!! when used in vehicles
It is of concern that many such inverters may still be in use with unsuspecting users .
As you say it is NOT a FULLY isolated inverter & as such should be dumped. Unless it can be fitted with an inbuilt RCD .
So Allan BACK TO GRAND MA FOR YOU FOR MORE LESSONS & your final shot is a failure.
I hope your knowledge of the real world in other electrical matters is better than the knowledge you have shown on this thread.

No matter how good the intent false ,incorrect ,misleading info on electrical matters can be dangerous

An RCD will protect circuits on the load side of the RCD.
If the fault occurs on the line side of the RCD the RCD can’t disconnect it.

In the situation where the inverter’s internal 250 volt circuit shorted to the inverter’s case, then even if the RCD operated, the case would be alive when compared to the line side of the RCD.

If it was a single pole RCD (as used in houses) then a life threatening situation could occur.
If it was a double pole RCD (as used at the ends of extension cords) one would guess that it would be safe even though the case was still alive - as a circuit couldn’t be completed with one of the other connections on the load side.

There are a lot of these cheap inverters without internal RCDs sold in Australia, and I have one of them, it’s hard to believe that authorities would allow them to be sold if they were unsafe.

Not having an engineer’s degree I won’t held responsible for my guess work.

Hi Dennis

You are pretty right with your post


Re this
"There are a lot of these cheap inverters without internal RCDs sold in Australia, and I have one of them, it’s hard to believe that authorities would allow them to be sold if they were unsafe"
I would say all cheap inverters sold now do not have a RCD. However they are now all fully isolated
However two often overlooked conditions apply to their use.
#1 You can use as many double insulated devices as you like
#2 ONLY ONE CLASS1 devise [one that requires an earth connection & will always have a 3pin plug]should be connected @ any time
Every additional class one devise connected increases the risk of a potentially dangerious fault developing
A reminder to all, if a fully isolated geny or inverter is connected to a van by the power inlet socket, your VAN RCD if fitted will not function .
Also be aware that the van itself becomes the first class one devise & all class one devises within the van encreases the risk,WITH NO RCD protection

Hi Dennis
RE "An RCD will protect circuits on the load side of the RCD.
If the fault occurs on the line side of the RCD the RCD can’t disconnect "

The RCD can ONLY operate IF there is an EN link before the RCD @ the power source.
Actually the earth fault is in the power source could form that EN link ,which then makes it potentially dangerous if used without a RCD as close as possible

I've got no argument with that.