Inverter Earth to Chassis

[DTDOG]

So, I'm hard wiring up a new 3k inverter (Pure Sine) which recommends I earth the unit to the chassis of the vehicle.
Am I right in thinking the engine etc has an earth strap to the battery negative. I'm wiring the inverter to two 11amp batteries in the habitation area.

My concern is that in the event of a short where the 240v goes down to earth (the chassis in this case) wont this cause damage to the 12v system connected to that same chassis via the earth strap?

Or am I getting confused?

 

[jeffmossy]

Use a ground spike then connect it to the van chassis with a jump lead

 

[DTDOG]

Use a ground spike then connect it to the van chassis with a jump lead

How will this stop it going to the battery negative via the engine earth strap?

 

[jeffmossy]

Your rubber tyres prevent your van from earthing, should you get a short in the ehu circuit then you have a true ground point to absorb the circuit

 

[DTDOG]

Your rubber tyres prevent your van from earthing, should you get a short in the ehu circuit then you have a true ground point to absorb the circuit

You are not understanding the question. I asked about the chassis being connected to the negative of the battery and the earth on the inverter, not about finding a good earth grounding point. You do make a good point about the tyres and assuming I am wrong about the battery side of things, then grounding the chassis with a spike and a croc clip is a good idea.

 

[jagmanx]

12 V Yes the Chassis or metal patrs thereof are OK but essentillay the neutral connection of a pair
No danger but not a true ground !

On full EHU the 3 pinplug/socket arrangement in UK privide a proper earth ( and sometimes abroad)
On Genny the 3 core cable will earth provided you have a ground spkike for the Genny
Inverter.
Most seem ro run inverters supplied by the vehicle 12 V .( ie 2 links +ve and -ve Thus not truly grounded
If Inverters have a seperate earth connection that could be grounded by direct wire (green or Yello and green) to a ground spike.
My reading suggests very few do this indeed some use inverters whilst travelling (so effectively off the alternator)
I leave it to thee true sparks to advise in thi
As has been posted the tyres isolate the vehicle from earth/ground
I have used an inverter just with the 2 connections without a problem. BUT always whilst stood.
Over to the electrogurus So await their responses..I m not qualified!

 

[trevskoda]

Mine is just grounded to the 12v neg feed wire, you wont get a shock from the inverter as its transformer decoupled, also tyres have carbon in them making a earth.
And you are going to have one hell of a set of batteries to power that, what are you trying to run.

 

[Wrighpm]

So, I'm hard wiring up a new 3k inverter (Pure Sine) which recommends I earth the unit to the chassis of the vehicle.
Am I right in thinking the engine etc has an earth strap to the battery negative. I'm wiring the inverter to two 11amp batteries in the habitation area.

My concern is that in the event of a short where the 240v goes down to earth (the chassis in this case) wont this cause damage to the 12v system connected to that same chassis via the earth strap?

Or am I getting confused?

If you have an RCD the electrical 240 trip will activate in milliseconds in the case of a live/neutral to earth situation. Damage to 12v systems would be very unlikely in my opinion in the short period before a trip occurs. A separate wire to chassis ground may be a reccommedation for current reasons as effectively the negative 12 v wire should be at same potential as the vehicle/battery earth. If you had a 240 short to earth and it did not trip the supply via an RCD then you will have more serious issues than a piece of damaged kit i.e. electrocution/fire.
I am saying this as a lay person with some self-taught electrical knowledge, I am sure I will be corrected if wrong. Good luck.

 

[xsilvergs]

If you have an RCD the electrical 240 trip will activate in milliseconds in the case of a live/neutral to earth situation. Damage to 12v systems would be very unlikely in my opinion in the short period before a trip occurs. A separate wire to chassis ground may be a reccommedation for current reasons as effectively the negative 12 v wire should be at same potential as the vehicle/battery earth. If you had a 240 short to earth and it did not trip the supply via an RCD then you will have more serious issues than a piece of damaged kit i.e. electrocution/fire.
I am saying this as a lay person with some self-taught electrical knowledge, I am sure I will be corrected if wrong. Good luck.

I had to change the wiring from the inverter to stop the vans RCD from tripping with a Victron inverter. The only thing I could attribute to the tripping was, when a load switches off, kettle, fridge etc there is an electrical spike created. In a domestic system that spike can be absorbed by the grid, in my van system the inverter could not absorb the spike and so the RCD would trip. I soon got bored with it tripping out.

 

[CriftinsCampers]

The black 12V negative lead to the inverter can either go to chassis ground or directly to the negative of the battery.
Assuming that is, that the battery negative is also connected to the vehicles chassis.

Best rule of thumb to determine this is use the shorter of the two runs as there could be less volt drop via the chassis over a distance.

The inverters AC 230V mains earth point (if it has one) should also be connected to chassis ground.
Ditto if you have mains hookup, that to should be earthed to chassis ground as per BS7671

Regulation 721.411.3.1.2 requires structural metallic parts that are accessible from within the caravan (aka Motorhome) to be connected through main protective bonding conductors to the main earthing terminal within the caravan.