240v consumer unit earthing

[Mud Digger]

I just found this on the interweb......

To comply with BS7671 sect 721 any PERMANENT 240 volt installation in a vehicle (including caravans and motorhomes etc) should have the incoming mains supply earth bonded to the vehicle chassis. It also worth noting that any metal gas pipes should also be earth bonded.

Seems like my gut feeling is incorrect (wouldn't be the first time either!!).

Deaks

thats where i was going next bringing in a 240v supply would need a bonding

 

[Mud Digger]

Hmmm, I'm still not sure about this. I did earth to the chassis when I installed the EHU consumer unit under the bonnet at the weekend.
I've not used it yet, but would like to be sure it's 100% as it should be.
Not looking forward to getting inside there again as it was super fiddly getting 3 x rcbos in the wylex enclosure!!

Deaks

Just make sure your have the chassis earthed onto the 240 v distribution earth point and bond any metal work and any pipework / metal not touching the chassis is what that reg is saying then you can just screw earth wires into the chasis

 

[Mud Digger]

wish i paid more attention at collage 17 years ago lol

 

[DXX]

Not often I use a EHU but I have seen some very dodgy campsite EHU in poorer European regions, certainly no guarantee that there is a good ground.

 

[Phil_G]

Not looking forward to getting inside there again as it was super fiddly getting 3 x rcbos in the wylex enclosure!!

Why three RCBOs? that sounds like expensive overkill for a camper
you wouldnt normally need separate earth leakage protection on each circuit... one double pole residual current device on the incoming feed and MCBs is the norm In a modest installation one double pole RCBO could do both jobs.

 

[oldiebut goodie]

Rubber tyres contain carbon black - ideal for earthing. I wouldn't consider a rubber tyre to be a total insulator.

 

[AussieMick]

The reason to earth your van is so that if a 240v active conductor touches something metalic due to bad insulation etc it will trip your residual current device or trip a circuit breaker or fuse. If your van is not earthed it will not do this and you have 240v waiting for someone or something to touch it creating a dangerous situation. So I would bond the earth to metal point on your van always hoping the EHU is properly taken back to a suitable main earth by the caravan park etc.

 

[Dellmassive]

I think we all get the idea that if you have EHU installed then the Vans body ground needs to be bonded to the earth bar in the CU,

and that as above the CU needs to have a RCD and DP MCB . . .

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my take on this was, what about the scenario where you HAVE EHU installed . . .

but you are OFF GRID and using a 240v inverter setup. (Not plugged into EHU)

or dont have EHU installed anyway.

what about the Inverter effectively bonding the 240v neutral & Inverter earth connection to the vans body/chassis 0v.


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so i suppose we are saying that in that scenario the inverter should be feeding the CU same as if it was a EHU, possibly with an auto transfere switch.?


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or if you had no CU, then the inverter should have its own stand alone plug in RCD and the inverter earth connected to 0v chassis ( so the RCD can detect the fault)?

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[AussieMick]

Sorry a few terms you use are not familiar to me. CU? DP MCB. Double pole Main circuit breaker ? Im in Australia and we probably use slightly different terms, took me a while to work out EHU

 

[Dellmassive]

https://www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf

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[Dellmassive]

this is what i was referring to about the neutral earth link . .

 

[Dellmassive]

Sorry a few terms you use are not familiar to me. CU? DP MCB. Main circuit breaker ? Im in Australia and we probably use slightly different terms, took me a while to work out EHU

CU - consumer unit
DP - double pole
MCB - mini circuit breaker
EHU - electric hook up

SP - shore power (boating term,same as EHU )

 

[Deaks]

Why three RCBOs? that sounds like expensive overkill for a camper
you wouldnt normally need separate earth leakage protection on each circuit... one double pole residual current device on the incoming feed and MCBs is the norm In a modest installation one double pole RCBO could do both jobs.

Hi Phil
First one is for the sockets in the van, that feed into the to the invertor/switchover circuit.
Second is for the Victron mains 30amp charger for the leisure battery.
The third (and currently unused) is for a smaller mains charger for the van/starter battery.

Overkill a bit I suppose, in relation to the third one, but being able to isolate the 30 amp charger is useful I think.

Deaks

 

[Dellmassive]

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[Skyliner33]

Consumer unit,

Sorry a few terms you use are not familiar to me. CU? DP MCB. Main circuit breaker ? Im in Australia and we probably use slightly different terms, took me a while to work out EHU

consumer unit
Double pole.
miniature circuit breaker.

 

[AussieMick]

Thanks for explaining those terms, as I dont know much about inverters I think I better butt out , The post by Dellmassive seemed to answer OP question. ( I think )

 

[Mud Digger]

Rubber tyres contain carbon black - ideal for earthing. I wouldn't consider a rubber tyre to be a total insulator.

i ll go test a tyre with ohms meter im interested now you say that dirt wet would all help

 

[Stuupid]

Wow, opened a can of worms with that question.
If the regs say earth the CU that's good enough for me. Thanks all

 

[The Bear78]

i would say your house is not your van is not .... your sat in your van 240 live or hit by lightning its the your fine sat in the Faraday cage thing till you step out

theres no ground to earth or short cut from your van its sitting on rubber less you dangle a little anti static chain for car sickness behind you..

the Van is grounded to its battery only its not earth ( we call it earth ) its a circuit there's no other influences, even grounded is the wrong name

Just so we're on the same page....
The OP asked about CU earthing and made no mention of an inverter. To that end I assumed we were talking about campsite EHU's.
I have earthed my 240 system to the van body so there is a safe path to ground any short and trip the CU. As per the instructions and evidently the regs aswell.
Certainly if only running an inverter earthed to the body I can see the potential danger.

 

[Skyliner33]

Rubber tyres contain carbon black - ideal for earthing. I wouldn't consider a rubber tyre to be a total insulator.

Have you never experienced a static shock from a car? Im sure the tyes cant be that good.

Just to be sure, I am in the earthed camp and have earthed the 240 system to the van body which itself is connected back to proper earth through the EHU earth cable.
I would have thought that any short to the van metalwork would immediately go to ground and trip the CU.

Me as well, but what about when off grid and using 230V from an inverter?