Generator ground

[superheat6k]

Whereas the 'Neutral' conductor should be tied to Earth at the position of generation, ideally with the casing of the generator, with some portable generators the manufacturers connect the ground / earth to a centre tap on the generator windings.

This is done to reduce the electric shock risk to half the standard output voltage.

However, this means such a generator no longer has a 'Neutral' and 'Live', but rather two half potential 'Lives'. If the one nominated as 'Neutral' is then connected to Earth then half the generator winding will have become short circuited, which the generator will not like and the output voltage from the other nominal 'Live' side will drop to ~ half the normal output voltage.

It may not be easy to find out if a particular generator has a centre tapped earth, especially with a Inverter based generator, so sometimes it is better to cut the provided earth cable internal link entirely (if this is accessible) and then ground out the neutral to chassis earth without the original internal earth link remaining, the connected wire once cut should be properly insulated.

If the internal earth link wire is not accessible then this generator should not be used on a boat, where an earth bonded neutral is absolutely necessary, except perhaps for dedicated direct plugged in power tools, or similar.

 

[jdc]

Grounding the centre tap of a generator, giving 115V between live and around and 115V between neutral and ground, would be unusual, and I _think_ (but don't know for sure, probably PaulRainbow does) would contravene the UK and EU regs: ISO 13297 / 2020 is the applicable standard under the EU recreational craft directive as well as the UKCA equivalent, and it foresees connection of neutral to ground, and insists that it be done at the generator in most cases, see:

6.8 The neutral conductor shall be grounded (earthed) only at the source of power, i.e. at the onboard generator, the secondary windings of the isolation or polarization transformer, the shore power connection or inverter. The shore power neutral shall be grounded (earthed) through the shore power cable and shall not be grounded (earthed) on board the craft or:

a) for systems using an isolation transformer or polarization transformer, both the generator or inverter neutral and the transformer secondary neutrals may be grounded at the AC main grounding bus instead of at the generator, inverter, or transformer secondaries;

b) for systems using an isolation transformer or polarization transformer, or no shore power provision, both the generator or inverter neutral and the transformer secondary neutrals may be ungrounded provided double-pole protection and switching is installed.

In that section it mentions grounded neutral system (TN-S) and an isolated 230V system (IT), but doesn't seem to envisage a centre tapped system. Superheat6k is right to warn one off such a system!

 

[Refueler]

What you're saying seems contrary to what the manufacturer says in the manual

My 3kw Handy Gen has the ground bolt in the frame and manual says about connecting that bolt to a grounding stake into the actual ground. I read it and I ask myself where is the continuity ... if the ground around the Genny where its stood does not complete a circuit - what use is it ?

But on another item .. the summer guest mobile (which came from UK) down near the boats is wired as per UK ... in accordance with the standards for Caravan Parks / Mobile Home sites ... the metal frame of the mobile is connected to the Earth of the electrical supply. This caused a bit of a stir here as then the frame was found to be carrying a voltage .. not enough to be a problem - but it was there. My pal - who owns and runs an Electrical Installation Company came and checked it out ... he spent some years working in UK before so he knew what to look for ... the solution was a 2m iron rod driven into the ground behind the mobile and frame connected to it.

There's a reason its nicknamed : Electrickery !!

 

[rogerthebodger]

The OP spoke about a generator for his boat not a land insulation.

Most generator including one of mine used for load sheading are used in a land installation where the spec specifies a ground spike at the supply substation and at the residence where the power is consumed.

A GRP boats and cars and camper vans are isolated from the surrounding by the GRP hull and the rubber tires

So, there is a difference

This discussion is quite interesting

SmartGauge Electronics - To bond or not to bond - Hulls and electrical earthing

Ship grounding - How earthing works for different types of ships?

earthing systems on ships

 

[billskip]

Grounding the centre tap of a generator, giving 115V between live and around and 115V between neutral and ground, would be unusual,

This is normal practice when supply is 110v.per phase and 2 phase 220v supply is required in some countries. It creates a problem when 220v voltage protection units are required as they get standard imported 220v l/n units, when they then "trip" one side of your appliance is still "live" at 110v.
Also this causes a problem when 2 or 3 phase is distributed in a building it can and usually does feed 110v back into other phase through light bulb etc.
110/220v generators can be wired with centre tap.

 

[PaulRainbow]

The OP spoke about a generator for his boat not a land insulation.

Most generator including one of mine used for load sheading are used in a land installation where the spec specifies a ground spike at the supply substation and at the residence where the power is consumed.

A GRP boats and cars and camper vans are isolated from the surrounding by the GRP hull and the rubber tires

So, there is a difference

This discussion is quite interesting

SmartGauge Electronics - To bond or not to bond - Hulls and electrical earthing

Ship grounding - How earthing works for different types of ships?

earthing systems on ships

We don't have ships, we have boats.

 

[PaulRainbow]

Ref #21 and #22 and centre tapped inverters or generators....

Current standards (as pointed out) require the neutral and Earth be bonded, they also require the Earth circuit to be "grounded" as in connected to the water. That for me means centre tapped equipment has no place onboard. I would refuse to fit such equipment. I'd also ignore suggestions of not fitting the Earth connection to the water.

As for the Honda generator that the OP is asking about, i specifically answered his question about that generator and i know that it is not centre tapped.

 

[rogerthebodger]

We don't have ships, we have boats.

But both float in water and both have mains power either connected to the shore or driven by an internal generator and both can be made from the same material.

Some RM mine sweepers have GRP hull.

You just will not even consider there are different requirements and only consider what you read which may or may not be the answer

 

[B27]

But both float in water and both have mains power either connected to the shore or driven by an internal generator and both can be made from the same material.

Some RM mine sweepers have GRP hull.

You just will not even consider there are different requirements and only consider what you read which may or may not be the answer

An RN minesweeper wouldn't want all the electrics going off just because some grubby rating is electrocuting himself.

 

[Refueler]

An RN minesweeper wouldn't want all the electrics going off just because some grubby rating is electrocuting himself.

The Tupperware boats !! I knew quite a few who sailed on those GRP Sweepers ... they developed cast iron stomachs against the seasickness !!

 

[PaulRainbow]

An RN minesweeper wouldn't want all the electrics going off just because some grubby rating is electrocuting himself.

Spot on, that's why ships are different to boats.

 

[PaulRainbow]

But both float in water and both have mains power either connected to the shore or driven by an internal generator and both can be made from the same material.

Some RM mine sweepers have GRP hull.

You just will not even consider there are different requirements and only consider what you read which may or may not be the answer

No, you won't accept the standards that the rest of the World agree on for leisure vessels and that the manufacturers provide in their literature. There is no room for ambiguity and it's really very simple to comply with. Doing it differently offer absolutely no advantage whatsoever.

You are so arrogant that you think you know better than all of the manufacturers, all of the standards bodies, common sense and good practice. Please stop posting potentially dangerous and non compliant rubbish.

 

[rogerthebodger]

Spot on, that's why ships are different to boats.

So what is the difference between a ship and a boat we still have to comply with the Col Regs and in fact ships and boat in my home country have to comply with all the same safety regulations designed to protect life and propriety at sea.

It just you who are trying to create a difference where there is not for your own benefit whatever you consider that to be

 

[PaulRainbow]

So what is the difference between a ship and a boat we still have to comply with the Col Regs and in fact ships and boat in my home country have to comply with all the same safety regulations designed to protect life and propriety at sea.

What do they have to do with electrical systems ?

It just you who are trying to create a difference where there is not for your own benefit whatever you consider that to be

The differences regarding electrical systems are well documented. Try reading what they are for leisure vessels.

 

[rogerthebodger]

What do they have to do with electrical systems ?

Designed many heavy power driven equipment through my Engineering career over 50 years not that is of any interest to you

The differences regarding electrical systems are well documented. Try reading what they are for leisure vessels.

Unlike you I do a lot of research in to all the activities I get involved with and not just those the confirm my viewpoint.

A common fault is conformation biased

Confirmation bias is a psychological tendency to favor information that confirms existing beliefs or values People exhibiting this bias are likely to seek out, interpret, remember, and give more weight to evidence that supports their views, while ignoring, dismissing, or undervaluing the relevance of evidence that contradicts them1. Confirmation bias is often unintentional but can still lead to poor decision-making in research and in legal or real-life contexts

This is also an issue that a lot people have is Dunning Kreuger effect. which can also be found with a Google search

No one can know earthing, but some know more than others and we can all learn from each other if we are amenable to lesioning to each other.

We all have different experiences and different knowledge only if we can open our mind to other ideas.

Just no disagreeing with a different viewpoint and name calling, and insults is just not acceptable.

I have always questioned convention as most of the Moden developments have come about innovators questioning convention and develop better and improved products and most of my Engineer career, I have been in development designing improved and better products. There has always been detractors so I always get my ducks in a row to defend against those detractors if necessary

So, I evaluate any of your statement as by other on the forum and analysis that facts given with my 70 years plus knowledge and experience and use the compline facts but when interspersed with insults, just puts people acceptance off and those with less expedience will tend to accept those who shout loudest.

Just my view which I don't think of care what you think and if any poster doesn't take my view no skin of my nose

 

[PaulRainbow]

Designed many heavy power driven equipment through my Engineering career over 50 years not that is of any interest to you

Same as Colregs and safety equipment requirements, nothing remotely relevant to modern marine electrical systems.

I'm not stuck in the 70's Roger, i'm working to current standards.

 

[rogerthebodger]

Same as Colregs and safety equipment requirements, nothing remotely relevant to modern marine electrical systems.

I'm not stuck in the 70's Roger, i'm working to current standards.

More insults!!! I am not stuck in the 70 design and develop Moden computer /micro processer-based equipment and not just install other peoples designed equipment.

That is your issue working to CURRENT standards which are developed based on past experiences no on current experience and current requirements.

The main difference between you and I is that I and a developer of equipment that create standards and you are an installer of current equipment and follow existing standards that by its nature reflect past knowledge.

We have different skills

I have had Electricians, electrical fitters' and wiremen working for me in industry, so I have a pretty good idea of their skills and level of knowledge

The safety requirements where I sail has requirements specified for Moden marine electrical systems inspections where you in the UK for sea going vessels do not have the level of inspection and compliance as we do

The world does not end st the shores of England, there is a big wide world out there with different standards and regulations

 

[Metalicmike]

I have an MCB and RCCB fitted on my 230v shore supply, this should give full protection should the earth path fails.

 

[lustyd]

I have an MCB and RCD fitted on my 230v shore supply, this should give full protection should the earth path fails.

That’s the point though, RCD might not work if the system isn’t correctly set up. It’s not magic, it needs a residual current to trip and that requires that ground works. If the current flows back via neutral it doesn’t trip because it’s not supposed to trip in that situation.

 

[Metalicmike]

That’s the point though, RCD might not work if the system isn’t correctly set up. It’s not magic, it needs a residual current to trip and that requires that ground works. If the current flows back via neutral it doesn’t trip because it’s not supposed to trip in that situation.

Sorry I meant RCCB