240v inverter earth

adhdan

Member
Joined
17 Sep 2023
Messages
100
Visit site
Im fitting a 250w victron phoenix 12v>240v power inverter, coming up stumped on where to fit the earth, the boat is GRP with inboard. I couldnt find anything suitable through the hull to earth to so can i earth to the engine/gearbox to create a path down the shaft to the water? The inverter is to power a smart tv using an extension cable running from the plug socket of the inverter
I have read through multiple threads about inverters but ended up more confused then anything :ROFLMAO:
Thanks
Dan
 

PaulRainbow

Well-known member
Joined
16 May 2016
Messages
15,803
Location
Suffolk
Visit site
If the shaft coupling is sold, ye. If it has a flexible couple with no bridge wire, no. In other words, there must be electrical continuity between the engine and the shaft (to the water). If not, do you have a hull anode you can connect to ? If non of those work for you, then fit a small button anode to the hull and use that.
 

adhdan

Member
Joined
17 Sep 2023
Messages
100
Visit site
If the shaft coupling is sold, ye. If it has a flexible couple with no bridge wire, no. In other words, there must be electrical continuity between the engine and the shaft (to the water). If not, do you have a hull anode you can connect to ? If non of those work for you, then fit a small button anode to the hull and use that.
Hi, thanks. Yes its solid connection from the gearbox to the shaft & through so i'll go that route. Does it need any kind of protection being connected that way from corrosion?
 

rogerthebodger

Well-known member
Joined
3 Nov 2001
Messages
12,406
Visit site
if sitting in an insulated plastic tub, what is the realistic risk of not having an earth ?

That is the question I have asked and not got a proper answer from the forum.

I will say that if a RCD is fitted in the mains output of the inverter in an insulated setup the a protective earth connected to the neutral output of the inverter and connected to any metal cas of the powered appliance if there is a mains to case fault in the appliance the RCD will trip thus protection any person who comes into contact with the metal case of the appliance

Also if there is a connection between the neutral and the inverter case as suggested by Victron and there is a fault in the inverter where the mains shorts to the inverter case the case of the appliance will become live and the RCD will not trip.

If there is a shutdown mechanism in the inverter that could protect the user in this fault condition.

I will no get criticised and accused of not knowing what I an talking about. Please analysis the setup and make your own mind up
 

adhdan

Member
Joined
17 Sep 2023
Messages
100
Visit site
if sitting in an insulated plastic tub, what is the realistic risk of not having an earth ?
im fairly sure if you stood in a boat and grabbed hold of a live wire from the inverter it would find a way, you might be partially insulated but you would get a zap. If you stand in a plastic bucket and grab an electric fence it still shocks you.
 

rogerthebodger

Well-known member
Joined
3 Nov 2001
Messages
12,406
Visit site
im fairly sure if you stood in a boat and grabbed hold of a live wire from the inverter it would find a way, you might be partially insulated but you would get a zap. If you stand in a plastic bucket and grab an electric fence it still shocks you.

Only if there is a conductive path between the live and neutral inverter outlets
 

adhdan

Member
Joined
17 Sep 2023
Messages
100
Visit site
Only if there is a conductive path between the live and neutral inverter outlets
i was thinking more along the lines of how insulated a boat really is, fiberglass wet on the outside, wet on the inside with condensation, water in the bilge, various metal through fittings, i figured you would get a shock as it finds a way to earth not to the neutral. Thats why i said about electric fence, in theory if your standing in a plastic bucket 100% insulated right? but ive still gotten shocks, less severe and some dont land at all but its not 100%
 

PaulRainbow

Well-known member
Joined
16 May 2016
Messages
15,803
Location
Suffolk
Visit site
I will no get criticised and accused of not knowing what I an talking about. Please analysis the setup and make your own mind up
Victron, who manufacture the inverter, and current standards dictate that the Case/Earth should be grounded "to the water".

I suspect that you don't know better than them and suggesting that people "make their own mind up" is reckless.
 

rogerthebodger

Well-known member
Joined
3 Nov 2001
Messages
12,406
Visit site
i was thinking more along the lines of how insulated a boat really is, fiberglass wet on the outside, wet on the inside with condensation, water in the bilge, various metal through fittings, i figured you would get a shock as it finds a way to earth not to the neutral. Thats why i said about electric fence, in theory if your standing in a plastic bucket 100% insulated right? but ive still gotten shocks, less severe and some dont land at all but its not 100%


The point about the flow of electricity is that the electric current MUST go back to the place it was generated be it AC of DC

Think a single pole switch in a light circuit. until the switch makes the circuit current will not flow and the light will not illuminate. The current will flow from the live , through the switch if closed , through the light illuminating he light then back down the negative line back to the supply.

This could be a simple battery of a generator or inverter ot the supply substation.

The protective earth is just an alternative path for the live current to go back to the supply device (inverter /generator)

The RCD is a device that measures the flow of electricity in got the live and neutral lines to the appliance and if thee is a difference will trip.

Most people don't understand the the difference must go some here and it will flow back to the neutral through the earth wire or through the earth spike at the supply. and a GRP ( insulated)some say that you fit an earthing point to the water. If you are nt n the water or on the ground how can current flow through you back to the neutral on an inverter. There is in my view not real point in having a earth(ground) point at there will be no return path via the sea water only vis the protective earth connected to the inverter neutral.

This is not covered in the Vectron web side of in the ISO standards

Also no seems to consider what it the is a short of the live supply inside the inverter.
 

PaulRainbow

Well-known member
Joined
16 May 2016
Messages
15,803
Location
Suffolk
Visit site
The point about the flow of electricity is that the electric current MUST go back to the place it was generated be it AC of DC

Think a single pole switch in a light circuit. until the switch makes the circuit current will not flow and the light will not illuminate. The current will flow from the live , through the switch if closed , through the light illuminating he light then back down the negative line back to the supply.

This could be a simple battery of a generator or inverter ot the supply substation.

The protective earth is just an alternative path for the live current to go back to the supply device (inverter /generator)

The RCD is a device that measures the flow of electricity in got the live and neutral lines to the appliance and if thee is a difference will trip.

Most people don't understand the the difference must go some here and it will flow back to the neutral through the earth wire or through the earth spike at the supply. and a GRP ( insulated)some say that you fit an earthing point to the water. If you are nt n the water or on the ground how can current flow through you back to the neutral on an inverter. There is in my view not real point in having a earth(ground) point at there will be no return path via the sea water only vis the protective earth connected to the inverter neutral.

This is not covered in the Vectron web side of in the ISO standards

Also no seems to consider what it the is a short of the live supply inside the inverter.
rogerthebodger has me on ignore, mainly because i disagree with this sort of drivel that he posts on every single inverter thread over on PBO ,so he won't see my reply.

So my reply is for anyone else reading this.

Please ignore his advice to "make your own mind up"

Please disregard the comment :
There is in my view not real point in having a earth(ground) point at there will be no return path via the sea water only vis the protective earth connected to the inverter neutral.

If this were true we wouldn't need an Earth when we're on shore power.

This is not covered in the Vectron web side of in the ISO standards

This is incorrect, Victron (and other major manufacturers of inverters) and the current ISO both require the inverter (in fact, any AC supply) to be grounded.
 

Seastoke

Well-known member
Joined
20 Sep 2011
Messages
11,335
Visit site
So my conclusion is as you say connect the earth to the neutral which is the same as PME SYSTEM in domestic properties , now the problem if you lose the neutral this make all things earthed live. This is why marinas and petrol stations don’t use the pme system. Also if you supply a remote say shed in your garden you should only take alive and neutral to it and install a separate earth rod. I am not conversant with inverter installations.
 

PaulRainbow

Well-known member
Joined
16 May 2016
Messages
15,803
Location
Suffolk
Visit site
i was thinking more along the lines of how insulated a boat really is, fiberglass wet on the outside, wet on the inside with condensation, water in the bilge, various metal through fittings, i figured you would get a shock as it finds a way to earth not to the neutral. Thats why i said about electric fence, in theory if your standing in a plastic bucket 100% insulated right? but ive still gotten shocks, less severe and some dont land at all but its not 100%
Some people seem to think that you cannot get a shock from 240v on a GRP boat because it's isolated from the "ground". This is not true. I have had shocks whilst standing on the wooden sole of a GRP boat. Conductivity isn't the same as if you're standing on the actual ground so the RCD may well not trip, but it isn't pleasant.
 

PaulRainbow

Well-known member
Joined
16 May 2016
Messages
15,803
Location
Suffolk
Visit site
So my conclusion is as you say connect the earth to the neutral which is the same as PME SYSTEM in domestic properties , now the problem if you lose the neutral this make all things earthed live. This is why marinas and petrol stations don’t use the pme system. Also if you supply a remote say shed in your garden you should only take alive and neutral to it and install a separate earth rod. I am not conversant with inverter installations.
It is a requirement of the current ISO that all fixed inverters and generators have the PE and neutral bonded at source. Most decent inverters are supplied thus.

Installation requirements for inverters are pretty clear, as are the AC/DC standards, but there is always the odd individual who thinks they know better.
 

rogerthebodger

Well-known member
Joined
3 Nov 2001
Messages
12,406
Visit site
Protective multi earth is normal where you have a protective earth from the neutral out to the powered equipment


0*A92qwtLUwMiY7OED.jpg


In this case the neutral and the earth line becomes the same as the is a duplicate protective as it can be seen that there is a ground point at both the supply Source and at the main protective bonding conductor

On a GRP boat with an inverter on the boat and water earth connector at the source and th load will be at the same point unlike in the above setup and your shed connector where the earthing points are separated connected by the ground that will conduct electricity unlike a plastic bucket or boat
 

rogerthebodger

Well-known member
Joined
3 Nov 2001
Messages
12,406
Visit site
Yes thanks , but this is not the same for marina supplies .

Very different to a marina supply which is the typical PME setup wit the extra issue as a disconnectable boat supply connection that could do go faulty

The same set also applied to a onboard generator
 

Seastoke

Well-known member
Joined
20 Sep 2011
Messages
11,335
Visit site
How do you mean ?
Marina earth is usually via a large earth rod or a earth plate in the water , the ESQCR apply to marinas but only on floating pontoons and fixed but not marina buildings , which can be supplied via TNCS SYSTEM commonly called pme .
 
Top