Question For A Sparkie. Inverter Earth.

**Blknight.aus** · 13th March 2015, 07:43 PM

Originally Posted by d2dave

Ok. Here are two pages from the manual.

In this pic it says to use 25mm cable for earth ground. This is surely a miss print? This would be my jumper leads.

Why is the earth on the DC side? Why does the earth need to be bigger than the DC in cables?

With AC in house wiring, the earth can be smaller than the active and neutral.

In the next pic what do I do with earth where I have indicated?

It also says to run a link from neutral to earth. Why don't they just do this internally?

It also does not show any earth connection into the wiring.

This is guess work atthis point becasue I dont have the manual in front of me. and it doesnt have a circuit diagram.

The earth wire needs to be at least the same size as the power wire as in the event of a fault to earth it needs to carry the full current of the power supply. in the setup that Im guessing this system provides its protection by relying on an active to earth fault shorting out the inverter.

the second image shows this. The loop wire that runs from neutral back to earth (which is the wire that you want to know what to do with) and what you do with that is tie it to the main earth point for the mains power of the van.

This is where my concern about how the van is earthed comes in. If the DC earth goes to the chassis AND the main earth ties to the chassis you can wind up with some interesting and, in the devils advocate worst case scenario scene, potentially fatal results if the inverter is not designed to operate with the DC and mains output Earth tied together.In most cases it simply results in the inverter faulting and requiring the fault to be rectified, sometimes fuses replaced but in some cases the inverter will just let its smoke out.

The reason they dont put the link in internally is because it provides part of the protection of the system and depending on how you install it you may not need it (for example if you patch it in correctly using an external RCD). The diagram setup shows the simplest and cheapest method that should work reliably if you build it up correctly.

Old school earth wiring required that the earth wire be able to carry the full current as it works as this inverter is configured to work, any fault from the active to the protective earth carried the current back to the MEN point effectively dead shorting the fuse and blowing it. This had issues because if you had a broken earth wire in an appliance that had a short to its body, were touching that appliance and then touched another that would then cause your body to carry the full current available till the fuse blew.

with the new system the RCD detects a much much lower fault current by means of white man magic, as the current rate is lower the cable can be smaller but it needs to have a lower resistance.

IF you were to wire up this inverter via an RCD and it had the internal link you would effectively be bypassing the RCD.

for the earth wiring to a 3 pin socket Im guessing that it wants you to run the earth from your chassis ground to the socket

IMHO
the quality of the manual should be the first indicator that perhaps you might not want to buy this inverter..... but that said.

I know how I would wire up that inverter but as I'm not certified to do install work I cant legally tell you. Im still going to stand by my previous advise of getting an inverter that has an AUS socket on it and run directly off of that without patching into the mains OR by running a lead to the van power inlet, but I'll up the ante if all your wanting it for is to charge a laptop and run some lights.

Convert all your lights to 12v DC stuff and run them off the batteries, put a charger in with the batteries and wire that to the mains inside the van get really clever and have the AC input drive a contactor that then completes the chargers circuit to the battery. For the laptop purchase a straight DC-DC charger and install a socket to suit. It will be more effecient and Id bet that if you were charging your laptop and operating it at the same time you'll be drawing more than the 1.2A@240v that that inverter would happily deliver.

**d2dave** · 13th March 2015, 11:23 PM

Originally Posted by p38arover

I feel like doing a Whirlpool forum treatment of this thread.....

I'd rather see a response from a qualified electrician for this type of question.

Dave, from the text in the diagrams, it's a product aimed at the US market (the reference to UL (Underwriters Laboratories) which doesn't apply here) and their regs are a lot different to ours.

It is made in 110 and 220 volts, so is made for both markets.

I was/am hoping that a sparkie will respond.

Ron, what is a Whirlpool forum treatment?

Dave. As for a different inverter, this is not an option as the one in question is already on a plane to me.

As for you saying you can't legally tell me how you would do it, there is no law against you telling me, probably a law that says you or I cannot do it though.

**p38arover** · 14th March 2015, 07:06 AM

Whirlpool Treatment?

Any question like this would be deleted immediately on the grounds that electrical work should be done by a licensed elec.

**Hogarthde** · 14th March 2015, 07:18 AM

Agree Ron, work should be done by licensed people. However ,in my experience, advice from Dave (blknight) and Tim (drive safe) ,is pure gold.

**Blknight.aus** · 14th March 2015, 09:55 AM

Originally Posted by d2dave

As for you saying you can't legally tell me how you would do it, there is no law against you telling me, probably a law that says you or I cannot do it though.

Like all things it depends on how you want to interpret the law.. I'd rather err to the side that covers my ass, tell you its not legal for me to tell you and then not tell you especially in an easily assessable public forum. This totally eliminates the chance of someone cut and pasting what I've written and me winding up with someone, who in all reality should have been left in a warning label free environment and permitted to darwin themselves out of the genepool, whining to me with a lawyer by their side about how they did what I said and scared themselves when something they did went wrong.

I'll counter offer tho...

If you don't get a sparky to come online and give you the answers you want, swing me a PM and I'll give you my email addy (which is a gmail address using my forum name before the @) so you can send me an email with the following.

1. the wiring diagram of your van
2. the specs and numbers on any of the switch gear and RCDs that are fitted to the van
3. if you have a cable head RCD on the power lead you use to nomrally power up the van
4. an accurate description with a rough physical layout diagram of what you want to achieve

I'll then mash all that into a specced up wiring diagram and see if I can track down one of the base sparkies to give it the offical yay/nay treatment and if it comes back as a yay then I'll send that back to you. IF you then have further questions about what I send back I'll do my very best to elaborate on or give you the same answer in a different way that you can understand.

in the mean time here's some things that you can do that could save you some time and sparky coin.

you can purchase the safety devices, cable and primary components
you can place the primary components where you want them,
you can run the wiring that you want where you want it
but
you cant make any connections or modifications to the existing power system or mount any of the gear that goes inside a powerbox.

And fresh off the phone from one of the sparky guys I was going to try and tap into.. (excuse the paraphrasing)

"Be careful when buying inverters from overseas, while they can make australian spec power not all of them meet AS. If you bring one into the country thats not compliant you assume all the importers responsibility"

my read on that is...

if your inverter is not AS compliant/approved/certified and someone cops a tickle from it the buck stops with you.

**p38arover** · 14th March 2015, 10:42 AM

Originally Posted by d2dave

It is made in 110 and 220 volts, so is made for both markets.

Not necessarily. Oz, like Europe is 230 volts. US homes are generally fed with A split phase system giving them 110 v and 220 v.

**Blknight.aus** · 14th March 2015, 11:05 AM

Sparky mate get back to me again after looking at the manual.

on first glance with assumed lighting and using the numbers from his laptops power supply (1.25A@240v) you're inverters not big enough and

"no"

My money....

Someone I trust with a better qual than me says "no".

My final word on the matter is and you may quote me

"What you're planning, as you're planning it, Don't do it"

Ron, at your and the OP's discretion, from my side this thread can be Whirlpooled

**d2dave** · 14th March 2015, 11:39 AM

Originally Posted by p38arover

Not necessarily. Oz, like Europe is 230 volts. US homes are generally fed with A split phase system giving them 110 v and 220 v.

So do how does this work with the Hz. US is 60 and Au is 50. The unit I am getting is 50Hz

**d2dave** · 14th March 2015, 11:49 AM

Originally Posted by Blknight.aus

on first glance with assumed lighting and using the numbers from his laptops power supply (1.25A@240v) you're inverters not big enough and

I currently have a 150 watt inverter which does every thing I want so this 300watt job will be more than enough.

Laptop is only used during the day and compact flouos, at 10 watts each, I could run 30. I never run more than two to three at a time to minimize battery drain.

Back to my original question. With this plug in type of inverter where does earth go. If an appliance that is made of metal gets a short and is live to its body, where does the earth go?

**Vern** · 14th March 2015, 12:26 PM

If what ever you plug into it is double insulated then you can get away without earthing it.
Hooking it to the vans earthing system is fine as long as its plugged into the mains.
Not plugged in, then make an earth stake, same as a generator system.
I haven't read the whole thread though.

Thread: Question For A Sparkie. Inverter Earth.

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