D.C. A.C. Grounds On Steel

[Chris Pink]

I've seen it before and nearly lost my brother because the earth was disconnected by a new plastic water pipe and not reinstalled properly.

 

Well, talking about "duty of care" and "friends and family" in this discussion, I thought you said you were an electrical engineer? Yet you allowed your brother to be electrocuted?

 

You should put you own house in order first, Mr L.

[Guest TerryL]

the regulations are delightfully vague saying only this;

 

"The neutral conductor shall be grounded (earthed) only at the source of power, i.e. at the onboard generator,

the secondary of the isolation or polarization transformer, or the shore-power connection. The shore-power neutral

shall be grounded through the shore-power cable and shall not be grounded on board the craft. "

 

however this;

 

http://www.energy-solutions.co.uk/dock_power.html

 

as fitted to sea-going yachts and intended to be used a portable interface between the yacht's systems and any old shore power worldwide is fitted in accordance with chris w's understanding.

 

Any other configuration gives no protection whatsoever and negates the whole point of installing an isolation transformer. (draw the diagram Terry L)

 

If you fit the unit on the bank then you protect yourself from the vagaries of the power at that location only.

 

Also it provides no peace of mind as the whole point of an isolation transformer is to give the end-user confidence in the configuration of the 240V power entering the vessel.

y

 

Still way over your head isn't it? Think about it, what does isolation mean?

 

They are called isolation transformers because they isolate physically and electrically. There is no contact on the secondary windings with the incoming mains supply or earth. It is then it's own isolated supply which makes it safer and also provides galvanic isolation if onshore. If it is fitted onboard a boat it will require a mains supply to it and an earth to work and equipotential bonding to the hull to keep it safe from faults. This negates the isolation both physically and electrically so there is no point in fitting it onboard now. The only way around this and to provide galvanic isolation is to disconnect the safety earth or fit an approved galvanic isolator. Note that the isolation transformer is no longer providing the galvanic isolation for the boat but acting in a different role of simply containing all secondary earth fault conditions within the boat. Earth fault conditions on the primary shore supply are handled by the GI or not at all if the hull is not earthed.

 

Do you understand that or were the people who took pains to teach me that in college and at work over the last 45 years also wrong? And yes I have drawn the diagrams, have you? Leaving something unearthed when it was needed is not something I was taught or agree with.

 

The point of an isolation transformer is to galvanically isolate the hull by electrical and physical means, it will also provide polarity protection. It cannot do the first role if it is onboard because you've stupidly brought the supply with it that you are trying to isolate the boat from! You then need to make safe that supply by earthing it to the hull, daft innit. Blame the people who make and sell transfomers for onboard use and conveniently ignore an important safety aspect.

 

 

 

Not only do you not know about electrics, but you are also ignorant of the law, whereas I have studied both.

 

In order to bring a suit against another person for negligence you have to prove ALL of the following:

 

1. They owe you a duty of care (see below for definition)

 

2. They breached that duty of care

 

3. You suffered damage as a result of the breach

 

 

To show that a duty of care exists the person giving the advice has to fulfill ALL of the following:

 

1. They are acting in their professional capacity when giving the advice

 

2. You were asking for and received their professional advice

 

3. It would be reasonable to assume that you would act on the advice or information given

 

So, unless all of the above transpired, then a negligence suit would fail. The info given is an "opinion" and not professional advice.

 

Chris

 

Good god a lawyer as well now, is there no limit to your talents?

 

Wrong....anyone can sue anyone.... but to be successful you have to prove the above on the balance of probabilities, I never said otherwise.

[carlt]

Wrong....anyone can sue anyone.... but to be successful you have to prove the above on the balance of probabilities, I never said otherwise.

So what you're trying to say is:

 

"You can be sued for offering advice, on a forum, but the plaintiff's action would not be successful."

 

Completely pointless statement really.

[chris w]

....anyone can sue anyone but to be successful you have to prove the above on the balance of probabilities, I never said otherwise.

 

1. No limit indeed... I haven't wasted my life as you appear to have done if, after 45 years of a job, you only know a little about electrics.

 

 

2. Of course anyone can sue you. I didn't say otherwise.... I said that they wouldn't win a case as illustrated unless they can prove all of the above.

Edited October 7, 2008 by chris w

[Guest TerryL]

Well, talking about "duty of care" and "friends and family" in this discussion, I thought you said you were an electrical engineer? Yet you allowed your brother to be electrocuted?

 

You should put you own house in order first, Mr L.

 

I wasn't involved and didn't know about until after he'd fitted the plastic pipe and was taken to hospital, then I put it right for him. In any event, would he have taken my advice any more than you would?

[chris w]

I wasn't involved and didn't know about until after he'd fitted the plastic pipe and was taken to hospital, then I put it right for him. In any event, would he have taken my advice any more than you would?

 

On the balance of probabilities, he's less likely to take your advice as he knows you even better than we do

[magnetman]

So what you're trying to say is:

 

"You can be sued for offering advice, on a forum, but the plaintiff's action would not be successful."

 

Completely pointless statement really.

 

If a professional person (A) on the forum suggested that I could sue someone (another professional person {B} for giving me bad advice on for example electrics and I found out later and after some legal expenses that I would never win such a case could I then take professional person (A) to court and sue them in an attempt to reclaim my legal fees as they had given me bad advice, on the forum?

 

 

edited to remove and replace with {B}

Edited October 7, 2008 by magnetman

[Scotty]

Unearthed installation sounds very dramatic

 

I don't have a shoreline on my boat so it is never 'earthed' all mains voltage generated onboard is bonded to the hull and protected by RCD

If I do need a shoreline then I will fit an IT on the boat, the isolated supply will also be bonded to the hull and protected by RCD

 

Then your boat will be unearthed from the shore supply if it is not connect to it, your risk! It is very dramatic if a fault develops you, your family and friends would be most at risk from electrocution! You could possibly get away with a faulty installation for years but one day the circumstances will change to the wrong conditions and...zap! I've seen it before and nearly lost my brother because the earth was disconnected by a new plastic water pipe and not reinstalled properly. The electricity board engineer who came to fix the line fault said they get a fatality once a week with unearthed installations, is that dramatic enough?

 

Where is this fault likely to develop?

 

There's the cable from land to the socket on the boat, then onboard there's the cable from socket to the Isolation Transformer

 

Even if there were damage to one of these short pieces of cable, the shoreline would be protected by an RCD on the 'shore', won't that trip as soon there's an imbalance?

[Guest TerryL]

So what you're trying to say is:

 

"You can be sued for offering advice, on a forum, but the plaintiff's action would not be successful."

 

Completely pointless statement really.

 

I didn't say it wouldn't be sucessful, how can I know? It depends on the circumstances, you can't ignore it if it happened and it would still ruin your day!

 

 

On the balance of probabilities, he's less likely to take your advice as he knows you even better than we do

 

That's right and look what happened to him! Daft as you lot.

[grahoom]

you can't ignore it if it happened and it would still ruin your day!

 

It seems I can't ignore this thread, and it seems to be ruining my day also!

[FORTUNATA]

According to my large book, there are two sorts of grounding systems on yachts at sea. If it's a steel boat there is the totally isolated from the hull D.C. circuit while any A.C. is grounded to a grounding point on the vessel. In such a case, both poles of the isolated D.C. circuits are protected by circuit breakers.

Fibreglass tend to have both D.C. and A.C. grounded but with the D.C. only the positive pole is protected via circuit breakers.

Isolation transformers have a core that must be grounded marina side. However, the casing of the isolation transformer is grounded to the vessel itself.

On canals, ot may not be so heavily regulated and there may be differences. Still, I believe many canal marine surveyors will quote the I.S.O. (International Standards Org) and that's the main standard set for yachts and sea vessels.

Still, as I said, none of this really affects my own boat as I don't have an I.T. installed.

 

the regulations are delightfully vague saying only this;

 

"The neutral conductor shall be grounded (earthed) only at the source of power, i.e. at the onboard generator,

the secondary of the isolation or polarization transformer, or the shore-power connection. The shore-power neutral

shall be grounded through the shore-power cable and shall not be grounded on board the craft. "

 

however this;

 

http://www.energy-solutions.co.uk/dock_power.html

 

as fitted to sea-going yachts and intended to be used a portable interface between the yacht's systems and any old shore power worldwide is fitted in accordance with chris w's understanding.

 

Any other configuration gives no protection whatsoever and negates the whole point of installing an isolation transformer. (draw the diagram Terry L)

 

If you fit the unit on the bank then you protect yourself from the vagaries of the power at that location only.

 

Also it provides no peace of mind as the whole point of an isolation transformer is to give the end-user confidence in the configuration of the 240V power entering the vessel.

[Guest TerryL]

If a professional person (A) on the forum suggested that I could sue someone (another professional person {B} for giving me bad advice on for example electrics and I found out later and after some legal expenses that I would never win such a case could I then take professional person (A) to court and sue them in an attempt to reclaim my legal fees as they had given me bad advice, on the forum?

 

 

edited to remove and replace with {B}

 

Possibly, if (A) actually said that, but he didn't did he? He said someone ( giving bad advice could be sued, that's just a warning!

 

 

It seems I can't ignore this thread, and it seems to be ruining my day also!

 

I'm trying to keep up with the replies, I seem to have stirred up a wasps nest!

[Chris Pink]

Where is this fault likely to develop?

 

There's the cable from land to the socket on the boat, then onboard there's the cable from socket to the Isolation Transformer

 

Even if there were damage to one of these short pieces of cable, the shoreline would be protected by an RCD on the 'shore', won't that trip as soon there's an imbalance?

 

He won't tell you because you might sue him if he's wrong and you live a long and healthy life.

 

 

The point of an isolation transformer is to galvanically isolate the hull by electrical and physical means, it will also provide polarity protection.

so the point of a shaving socket is to galvanically isolate my beard?

 

and why do these http://www.fairline-yachts.com/targa/index.php?l=en have a risk of gavanic corrosion to the hull?

 

btw AC doesn't have polarity. Think you should sue your teachers.

 

You then need to make safe that supply by earthing it to the hull, daft innit.

no, not daft, there can be no stray currents if the supply is isolated, there is a connection from the secondary to the hull to provide RCD protection.

 

Do keep up.

Blame the people who make and sell transfomers for onboard use and conveniently ignore an important safety aspect.

 

As you have rightly gathered i would much rather trust the experts in the field than you. And i would point out that a major symptom of psychological problems is being convinced you are right when everyone else says you are wrong.

Edited October 7, 2008 by Chris Pink

[FORTUNATA]

By the way, I don't seek to cause a World War Three with this thread so let's all keep the discussion friendly and positive. It would seem many experienced electricians don't always agree on certain matters and the same even applies to books on the subject. The most important thing is to be safe on board as I suppose an influx of 240 volts in a steel surrounding may well have caused many a nasty shock.

[carlt]

By the way, I don't seek to cause a World War Three with this thread so let's all keep the discussion friendly and positive.

Never start a thread on electrics they are never friendly or polite.

[Guest TerryL]

1. No limit indeed... I haven't wasted my life as you appear to have done if, after 45 years of a job, you only know a little about electrics.

 

 

2. Of course anyone can sue you. I didn't say otherwise.... I said that they wouldn't win a case as illustrated unless they can prove all of the above.

 

1. If you know so much why can't you give any sensible responses to my comments which are based on regulations such as equipotential bonding?

 

2. Actually you did say otherwise.... "In order to bring a suit against another person for negligence you have to prove ALL of the following:" You can bring a suit against anyone without proving anything first, shows how little you actually studied!

[Chris Pink]

1. If you know so much why can't you give any sensible responses to my comments which are based on regulations such as equipotential bonding?

 

If you know so much why won't you give any sensible response to Scotty's question?

 

He has asked you twice now.

[Guest TerryL]

By the way, I don't seek to cause a World War Three with this thread so let's all keep the discussion friendly and positive. It would seem many experienced electricians don't always agree on certain matters and the same even applies to books on the subject. The most important thing is to be safe on board as I suppose an influx of 240 volts in a steel surrounding may well have caused many a nasty shock.

 

I quite agree, I always look at the safest way to do a job but you can't call an electronics bod or someone writting a book an experienced electrician, the information they glean is often wrong and they miss the important fine detail which comes from experience and training.

[smileypete]

Even if there were damage to one of these short pieces of cable, the shoreline would be protected by an RCD on the 'shore', won't that trip as soon there's an imbalance?

 

AIUI shoreline RCDs are not yet a legal requirement.

 

So it's difficult to guarantee a boat will always have an RCD protected shoreline.

 

cheers,

Pete.

Edited October 7, 2008 by smileypete

[chris w]

I quite agree, I always look at the safest way to do a job but you can't call an electronics bod or someone writting a book an experienced electrician, the information they glean is often wrong and they miss the important fine detail which comes from experience and training

 

OMG, we're going to get the "University of Life" diploma unfurled in a moment. It's perfectly understandable that a poor educational background, a low IQ and a chip on your shoulder have made you the way you are. Poor you.

[Guest TerryL]

Never start a thread on electrics they are never friendly or polite.

 

Well they could be friendly but when they are proved wrong some people who think they are an expert become obnoxious and start the name calling. They are not interested in a different viewpoint which undermines their long held beliefs even when they can't argue against it, they have to be right when wrong.

[Chris Pink]

AIUI shoreline RCDs are not yet a legal requirement.

 

I would have thought if not already covered as outdoor supplies then my reading of BS7671:2008 would imply that they are. Although this does apply to new installations.

 

If there is no shore based RCD then any earth fault upstream of the boat is vulnerable.

[chris w]

Well they could be friendly but when they are proved wrong some people who think they are an expert become obnoxious and start the name calling. They are not interested in a different viewpoint which undermines their long held beliefs even when they can't argue against it, they have to be right when wrong.

 

I would refer you to my answer some time ago. It appears that YOU cannot understand the counter argument. I fully understand the point you are making but you seem to miss the point that if one follows your "advice" one would never install an IT on one's boat because it would be doing nothing in terms of galvanic protection.

[Guest TerryL]

name='chris w' date='Oct 7 2008, 01:17 PM' post='278960'

I quite agree, I always look at the safest way to do a job but you can't call an electronics bod or someone writting a book an experienced electrician, the information they glean is often wrong and they miss the important fine detail which comes from experience and training

 

OMG, we're going to get the "University of Life" diploma unfurled in a moment. It's perfectly understandable that a poor educational background, a low IQ and a chip on your shoulder have made you the way you are. Poor you.

 

You know the feeling then?

[carlt]

Well they could be friendly but when they are proved wrong some people who think they are an expert become obnoxious and start the name calling.

Actually, Terry, this is rather the impression I got of you.