Earthing 240v

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Southdowns

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Hi all,
I believe that I read somewhere maybe on the forum that a motorhome's 240v supply is earthed back through the EHU? So my question is if I am producing 240v through an inverter but not on an EHU how is my supply earthed, do I need a separate ground spike?

Thank you
 
65 views and no comments. Was it a silly question?
 
Inverter is an isolated output so doesn't need an earth. If you want to use an RCD with one you need to bond one of the outputs to the negative/earth in the van..
 
Sorry, I don't know what an isolated output means? My thoughts were that its still 240v and would require an earth? Is the negative /earth in the van a true earth as the 4 tyres act as insulation between the ground and the metal chassis

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Would a plug, plugged into the EHU with a decent bit of bonding / cable attached to a ground spike do the job, or am I being over cautious?
 
I only half understand Lenny HB answer but believe me he is the man in the know... taking a stab that what he means is that an inverter is only taking 12v in and converting to 240v independently from "mains 240v supply" so no need to earth it..... HOWEVER probably talking site 🤣🤣🤣🤣
 
My inverter has an earth lead attached to it which, according to fitting instructions, should be attached to the 'ground' of the van. I attached it to a metal part of the drivers seat where the leisure batteries are also earthed to.
 
VXman said:
My inverter has an earth lead attached to it which, according to fitting instructions, should be attached to the 'ground' of the van. I attached it to a metal part of the drivers seat where the leisure batteries are also earthed to.
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But surely that is normal vehicle earthing because it is supplied from your vehicle 12v system ..not what OP is asking and driving a ground stake into the ground to earth his mains supply 240v supply system.!
Sorry reread OP,s and yes I believe you are correct.. inverter only needs earthed to vehicle.... Sorry.
 
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poppycamper said:
But surely that is normal vehicle earthing because it is supplied from your vehicle 12v system ..not what OP is asking and driving a ground stake into the ground to earth his mains supply 240v supply system.!
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No, he asked how he should earth 240 volts coming from an inverter which is what I am doing. Inverter - coming off 12 volt battery, ramps up to 240v. How to earth was the question.

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Southdowns said:
Sorry, I don't know what an isolated output means? My thoughts were that its still 240v and would require an earth? Is the negative /earth in the van a true earth as the 4 tyres act as insulation between the ground and the metal chassis
Click to expand...

This is the bit I don't understand. So my inverter is earthed to the van. I wonder, like you, how that is earth when the tyres are made of rubber!
 
As I understand it,.....................

....................................................................................

....................(errr,..... :unsure: no I don't think I do so the rest of my waffle deleted).
 
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VXman said:
This is the bit I don't understand. So my inverter is earthed to the van. I wonder, like you, how that is earth when the tyres are made of rubber!
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It’s not earthed, it’s grounded (bonded) to the negative grounding of the vehicle. It offers no protection.
 
Does an RCD on the output from the inverter help with protection, so that if there is any leakage to the vehicle’s chassis, does the RCD cut the supply?
 
Raul said:
It’s not earthed, it’s grounded (bonded) to the negative grounding of the vehicle. It offers no protection.
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Sorry Raul . Can you please elaborate the statement it "offers no protection".
To what are you referring?? Genuine question?

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Southdowns said:
Sorry, I don't know what an isolated output means? My thoughts were that its still 240v and would require an earth? Is the negative /earth in the van a true earth as the 4 tyres act as insulation between the ground and the metal chassis
Click to expand...
As you say, in the van does not exist earth, PE protective earth. It’s only found in fixed AC ground installation, or mobiles with hook up, or shore. In absence of grid PE, on a mobile and boats, we use double insulated output inverters. That means, if you touch one cable, but without touching the second, there is no circuit to complete, so no current flow.
In situation where a rcd it’s needed, then a return path to source it’s needed to function. That return path it’s the PE conductor, in our mobile case, a floating earthPE that’s bonded to the neutral output of the inverter. Grounding it’s NOT earthing, grounding it’s bonding together to a buss chassis usually the negative DC. Earthing, it’s only found in AC and has a earth rod.
 
Southdowns said:
Would a plug, plugged into the EHU with a decent bit of bonding / cable attached to a ground spike do the job, or am I being over cautious?
Click to expand...
Earthing needs a path back to source. How it’s that helping you for a return path, since your source it’s inside the van, the inverter. Your PE should go back to source and bonded to the output neutral, before you feed the distribution fuse box, rcd, mcb, rcbo. This it’s a floating earth since no spike.

The only time you put a spike in for a outbuilding it’s because the supply has a spike to, so you try to give a return path with least resistance back to source.
 
Southdowns said:
Hi all,
I believe that I read somewhere maybe on the forum that a motorhome's 240v supply is earthed back through the EHU? So my question is if I am producing 240v through an inverter but not on an EHU how is my supply earthed, do I need a separate ground spike?

Thank you
Click to expand...
If I can chip in, the answer is you don't need a ground spike.

The "why not" is where it might get a bit more complicated. In your home the supply has live and neutral wires. If you touch the live wire the current flows through you to the ground you are standing on. It can do this because the neutral side is itself connected to the ground. This is why you get a shock touching the live side - you complete the circuit.

With a typical inverter there is no concept of live or neutral in the output. You can touch either wire and you won't get a shock as there is no return path the current can take. You would only get a shock by touching both wires at the same time, which is unlikely to happen in normal circumstances.

HOWEVER (and the CAPITALS are deliberate) this only applies to the majority of installations. It is possible to connect one side of the output to the vehicle chassis and there are "centre-tapped" designs which create an artificial earth. These should have an RCD but might not and you could get an electric shock.

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Sorry to hijack the thread, but my recently acquired Honda generator has an external earthing stud on it's frame, when/what are you supposed to do with that ?
 
jockaneezer said:
Sorry to hijack the thread, but my recently acquired Honda generator has an external earthing stud on it's frame, when/what are you supposed to do with that ?
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You can earth it with a 1m spike driven into the ground & don't forget to water it.
 
jockaneezer said:
Sorry to hijack the thread, but my recently acquired Honda generator has an external earthing stud on it's frame, when/what are you supposed to do with that ?
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I wouldn't do anything with it. How many times have you seen a little generator earthed? I never have 😎
 
Lenny HB said:
You can earth it with a 1m spike driven into the ground & don't forget to water it.
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the earth electrode provided on say the Honda portable generators does nothing more than connect the framework of the generator to the ground... a portable generator or at least most are just like the inverter mentioned.. ie a floating earth.. so in most cases the ground spike is meaningless unless you alter the generator coil wiring... and some generators provide that facility, but its fraught with possible issues unless you know the application for which it is to be used... at least I believe that to be the case..

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Raul said:
As you say, in the van does not exist earth, PE protective earth. It’s only found in fixed AC ground installation, or mobiles with hook up, or shore. In absence of grid PE, on a mobile and boats, we use double insulated output inverters. That means, if you touch one cable, but without touching the second, there is no circuit to complete, so no current flow.
In situation where a rcd it’s needed, then a return path to source it’s needed to function. That return path it’s the PE conductor, in our mobile case, a floating earthPE that’s bonded to the neutral output of the inverter. Grounding it’s NOT earthing, grounding it’s bonding together to a buss chassis usually the negative DC. Earthing, it’s only found in AC and has a earth rod.
Click to expand...
The is the best explanation so far and smack on.
 

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