Earth return ?

[Tony Brooks]

You can but if the fixing fell off but the 12V and 240V bond stayed together an AC fault could put 240 volts on the DC circuits so its safer to make the hull connection in close proximity to the DC one.

If this is a flexibly mounted engine and the 12V "earth" is on the engine block I would add another bond between that point and a steel engine bed. Otherwise a 12V short to earth on the boat may try to fry the control cables.

[smileypete]

I would not use the batt negative as it's not obvious it's a safety earth and may get disconnected during maintenance.

Best just follow the manual, and why not ring them up for any extra advice, especially if you're not 100% sure?

[nicknorman]

As said earlier, the correct way is to connect a seperate earth wire from the Victron to a point on the hull adjacent to where the battery negative is connected to the hull. It is incorrect to use one wire for both the 12v negative and the mains earth. 

Edited May 29, 2017 by nicknorman

[WotEver]

If the main Earth bond to the hull is from the earth busbar in the consumer unit then it shouldn't matter if shore power is connected or not. I've always been somewhat confused by Victron's advice to separately earth the chassis - are they saying that the unit's chassis is not connected to the unit's earth output terminal?

As for where the AC earth bonding point should be, as others have said, adjacent to but not concurrent with the DC bonding point. I'm pretty sure that's explained in the link I gave earlier. 

[smileypete]

2 hours ago, nicknorman said:

As said earlier, the correct way is to connect a seperate earth wire from the Victron to a point on the hull adjacent to where the battery negative is connected to the hull. It is incorrect to use one wire for both the 12v negative and the mains earth. 

I doubt it's worth taking the green/yellow safety earth all the way to near where the engine earth strap is fixed to the hull, more chance of it being damaged or disconnected. Just take it to somewhere convenient near the consumer unit/combi.

ISTR from the discussions the other day on pitting woes, it may be best to take the engine earth strap to a stud fairly near to where the stern gland is, if there's continuity between engine and propshaft (ie no rubber coupling)

Edited May 29, 2017 by smileypete

[WotEver]

51 minutes ago, smileypete said:

I doubt it's worth taking the green/yellow safety earth all the way to near where the engine earth strap is fixed to the hull, more chance of it being damaged or disconnected. Just take it to somewhere convenient near the consumer unit/combi.

Or just connect it to the earth output of the unit (assuming that Victron haven't already done so), if the earth bond comes from the consumer unit. 

[steve7a3]

Ok. That all makes sense.

I can't see any other earth connection on the in-board side of the Victron apart from the chassis ground so I'm reasonably sure that it's the only earth/hull bonding point. 

In my case the nearest convenient hull connection is through the rear bulkhead into the engine bay anyway, so I may as well connect it as close as possible to the engine earth.

[WotEver]

Okay, I've now confirmed this with Victron. The input earth is connected to the output earth, as is the case. So if the wiring follows standard practise with the Multiplus output going to the Consumer Unit and an earth bond from Consumer Unit to hull you DO NOT need to wire another separate earth bond from the case. 

2 hours ago, steve7a3 said:

I can't see any other earth connection on the in-board side of the Victron apart from the chassis ground so I'm reasonably sure that it's the only earth/hull bonding point. 

So you don't have an AC earth bond from the Consumer Unit to the hull?

[steve7a3]

This is something I will now need to check. I assume there is because there's an RCD but I haven't physically seen it.

I had assumed that the output earth/consumer unit was connected to the chassis of the Victron. (and hence to the hull when that connection was made).

In this case, best not to assume anything!

Edited May 30, 2017 by steve7a3

[WotEver]

3 minutes ago, steve7a3 said:

I assume there is because there's an RCD

Nothing to do with it I'm afraid. 

[steve7a3]

Well, now I am a bit stunned. Just looked at my consumer unit(s) and it looks like the inboard-earth is simply connected to the outboard-earth on the inboard side of the galvanic isolator. Pretty sure that's not right.

 

[steve7a3]

Sorry, should explain those photos:

On the right is the RCD for the inboard circuits.

On the left is the breakers/RCD for the mains circuits (Immersion heater & charger/inverter)

The earth lead from the birds nest on the right comes across to join on the earth bus on the box on the left.

 

[Tony Brooks]

What are the thin brown and Brown with black trace wires that appear to be connected across the GI? (I may have this all wrong!!)

 

I have tried enhancing the photo but even so I can not see that green cable passing under the earth busbar. I agree with you it LOOKS as if both GI cables are connected to the earth Busbar.

Edited May 30, 2017 by Tony Brooks

[steve7a3]

The thin brown wires go to the GI status monitor (the one that started me on this quest).

Have just managed to have a consult with the resident sparky at the marina and he has clarified things for me. Both inboard & outboard earths (and the Victron chassis) should be connected together in the inboard side (as they appear to be) and then to the hull bonding point. If I can't establish that they are bonded to the hull then there's no harm in running another lead, via the Victron chassis, to the hull. So, this is what I'll do as, without removing the consumer unit/s from the wall, or at least pulling the breakers out, it's virtually impossible to see what's behind them.

I've checked with a meter and the shoreside earth of the GI is not connected to the busbar so at least that bit is ok.

Edited May 30, 2017 by steve7a3
Changed "outboard" to "shoreside" in last paragraph for clarity.

[WotEver]

36 minutes ago, steve7a3 said:

Both inboard & outboard earths (and the Victron chassis) should be connected together in the inboard side (as they appear to be) and then to the hull bonding point.

I don't understand what this means.

The shore power should connect to the input of the Victron. The earth from the shore power should go to the Victron via the GI. The output of the Victron should go to the consumer unit. The consumer unit should have an Earth bond from the earth busbar to the hull. That's it. No wires from the Victron chassis to the hull, nothing 'connected together'. 

Shore--Victron--CU

CU earth -- Hull

[Tony Brooks]

I am not qualified in mains electricity but taking your statement at face value it seems the resident sparky may not be as well.

A GI sits in the earth cable between the shore power inlet and the rest of the boat so any voltage (up to the diode turn on voltage) on the either side of the GI is prevented from flowing between the boat and the local earth for the shoreline pillar. (as I understand it). At the moment it seem your GI is sitting in parallel with the earth busbar and doing nothing - the busbar is in effect short circuiting it. How's your hull pitting?

I would suggest (perhaps WotEver will confirm, but I think he has) that the incoming earth cable shoudl run to one terminal on the GI and the other terminal should run to the busbar.

What I do not understand with the way it seems to be wired is how the remote monitor can think there is a fault present because both GI terminals should be at earth busbar potential. Unless the monitor has more connections I would expect it to show the GI is working and there is no voltage difference across it. That is a safe and working situation.

Are you 100% sure that plain green wire does not run right through the RCD box and on to the shorepower socket?

[WotEver]

2 minutes ago, Tony Brooks said:

I would suggest (perhaps WotEver will confirm, but I think he has) that the incoming earth cable shoudl run to one terminal on the GI and the other terminal should run to the busbar.

That would indeed be the 'standard' case without a Victron Multiplus. In this case, because the Multiplus can 'add to' the incoming mains, the shore power doesn't go to the CU; it goes to the Multiplus. So all three wires, L, N & E (via the GI) go to the Multiplus. The output of the Multiplus then goes to the CU. The hull Earth bond goes from the CU earth busbar to the hull. 

At least, that's how it should be wired. 

To clarify re: the GI. The shore power earth goes to one terminal. The other terminal goes to the Victron. 

[WotEver]

9 minutes ago, Tony Brooks said:

Are you 100% sure that plain green wire does not run right through the RCD box and on to the shorepower socket?

That's what I think it does. 

[Tony Brooks]

Yeh, its what I hope it does but when I lightened and looked at the photo full size I could not see it.

[WotEver]

6 minutes ago, Tony Brooks said:

Yeh, its what I hope it does but when I lightened and looked at the photo full size I could not see it.

 No, but I can't see it connected to the earth busbar either. As it's solid green the L & N wires might well be red & black and I can't see those either, so I suspect that shore power enters from the back of this box. 

[steve7a3]

To clarify. The top connection on the GI is the onboard one and goes to the busbar. The lower connection is the shore power one, bypasses the busbar and goes somewhere behind the breakers, I assume out to the shore power socket. There is NO (detectable) connection between the shore power terminal and the busbar so the GI is wired correctly.

I can't see any connection from the busbar to the hull.

The output earth and the input earth are all joined together at the busbar and to the earth connection of the Victron. The Victron chassis is not connected although the Victrol manual (and my marina sparky) say it should be.

So, to sum up, I don't know (because I can't yet see it) if the busbar is connected to the hull anywhere. Therefore my intention is to run a new earth from the busbar, via the Victron chassis to the hull bond point which should ensure everything is connected as it would be. At least that way I'll know I have at least one earth point to the hull.

[WotEver]

1 hour ago, steve7a3 said:

my intention is to run a new earth from the busbar, via the Victron chassis to the hull bond point which should ensure everything is connected as it would be. At least that way I'll know I have at least one earth point to the hull.

That will be fine. You do not need to wire it via the Multiplus chassis (it's just one more connection that could fail) because the chassis is already connected by the earth wire within the CU, but if you really want to then it won't do any harm. 

The Victron specialist that I spoke to earlier said that sometimes owners insist that the case must be separately earthed because they read it in the manual and in those cases he does so just to keep them happy. 

[steve7a3]

Update: I have now connected the Victron chassis to the hull (as per the manual and advice from Galvanic Isolator UK), via a convenient bolt near the engine mount. All indicated faults, AC (two lights on the GI status monitor) and DC (one light on the status monitor when the Victron was isolated) have gone. All power sockets are showing correct earthing both with and without shore power. 

Seems to have fixed the problem even if I can't explain why.

[MtB]

Threads like this make me SO pleased my boat is 12v and 24v only!

[WotEver]

11 hours ago, Mike the Boilerman said:

Threads like this make me SO pleased my boat is 12v and 24v only!

If the wiring is correct for a Multiplus (shore power to input, output to CU) and the earth bond is in place from CU to hull then it will all work correctly and it really doesn't have to be complicated. 

The whole 'chassis must be connected to hull' thing in the manual is satisfied by the CU earth bond.

People such as the guy from Galvanic Isolator UK who state that another bonding cable is required quite simply either don't know what they're talking about or they're taking the line of least resistance and getting the boater to bodge an incorrect installation by putting a bond in the wrong place.