A simple mains installation

[Supermalc]

For once Chris I am in full agreement with you.

 

When I wrote about 110 and 240 volt mains I should have said it is safer, not safe, and yes I know it is the current that kills.

 

On building sites it is usual for tools to be 110v used with a transformer. This is because it is safer, and safety is not put before cost.

 

I will say however, a competent person can successfully wire an instillation, be it house, boat, caravan, whatever.

 

However he MUST have access to the CORRECT instruction to enable him to do this.

[tidal]

The wheels on the bus go round and round

 

I rather think the wheels have come off!

 

 

At the risk of getting involved in a obviously long-running feud in my humble opion anyone who wires up a mains system to a metallic structure, especially one that floats in water without bonding the earth is either looking to get a nomination for the Darwin Awards or s hopefully long sentence for criminal negligence when they kill some innocent visitor.

 

The same applies to anyone who automatically trusts the wiring in a marina. ( I have seen some REALLY interesting examples in my travels)

 

 

That being said, going back to the original question, can the experts on here suggest a basic layout that would be appropriate to a narrowboat with fairly minimal mains supply requirements say for top up battery charging and occasional use of TVs computers etc.

 

I KNOW how I would do it for a grp yacht (I've done a fair few now) but I for one would value links (hopefully with block diagrams) to show current best practice as I agree with Malc on this it is NOT impossible for a reasonably sensible and competent person to carry out this sort of installation.

Edited September 17, 2007 by tidal

[ChrisPy]

For once Chris I am in full agreement with you.

careful, now

[Gary Peacock]

[tidal]

I have occasionally resembled that picture

[Gibbo]

To clarify-

 

In the case of a typical sized steel hulled narrowboat in fresh water an RCD will *probably* trip in the event of a full live-earth fault even if the earth is not bonded to the hull. Note the word "probably". There is no *certainty* that it will trip as it depends upon the conductivity of the water, the distance from the side/bottom of the canal, the depth of water, the condition of the underwater painting/blacking etc. If it does not trip, it creates a serious shock hazard to anyone not on the vessel (those inside it will be fine). If, as a result of not bonding the earth to the hull, someone was killed then the owner of the boat, or the person who installed the electrical system could, in theory, be charged with manslaughter. This is quite simply because EVERY electrical installation guideline, regulation or code worldwide dealing with private vessels says that the AC earth should be bonded to the hull. There are NONE that say it is ok to *not* bond it. Not a single one. Therefore if the system is not bonded then due care has not been taken.

 

In the same installation, if the earth *is* bonded to the hull then the RCD *will* trip.

 

In salt water it is almost certain that the RCD will trip whether or not the earth is bonded to the hull.

 

In the case of smaller boats, or those of non steel construction, the probability that the RCD will *not* trip becomes higher and higher until the point is reached where in the case of a GRP boat with just a few bits of metal below the surface (say a couple of anodes and an outdrive), the chances of the RCD tripping are almost zero.

 

An RCD *does* need earth in order to operate. Anyone who says it doesn't simply does not understand how they work. However the water will often provide the required earth path but not always. If there is no guarantee that the water will always provide the required earth path (which there isn't) then it is necessary to add a definite path by bonding earth/hull.

 

If you don't bond earth/hull you are asking for trouble.

 

As an aside. In the case of residentail vessels the system has to be certified by a part P electrician who knows jack shit about marine electrical systems. What a laugh.

 

Gibbo

[ChrisPy]

At the risk of repeating myself, I am surprised that anyone considering doing an installation like this would not spend £20 on a couple of books on the subject where all is revealed. I have 6 different resources to instruct and guide me on mains installations on boats, including 4 books. I like to think that I now have a reasonable competency in the subject. But I would not want to depend on finding consistent and reliable technical advice on a general boating forum like this one.

[Gibbo]

That being said, going back to the original question, can the experts on here suggest a basic layout that would be appropriate to a narrowboat with fairly minimal mains supply requirements say for top up battery charging and occasional use of TVs computers etc.

 

http://www.smartgauge.co.uk/nb_ac_sys.html

 

Gibbo

[tidal]

Thanks Gibbo. Much appreciated.

[Alastair]

http://www.smartgauge.co.uk/nb_ac_sys.html

 

Gibbo

The first diagram is what I have put on our narrowboat. Wish I'd known about this site before I started the installation - I wouldn't have sweated so much over it!

 

One thing I've added is a standard battery charger. It's a conventional garage/car type, that senses a drop in the battery voltage and detects when to start and stop charging. About £30 from Screwfix. The battery charger is just plugged into a socket in the cabin. There is no inverter, so chance of a inverter supplying a charger that's connected to the inverter . . .

 

When the boat is off the shoreline, charging is done off the alternator via a splitter to the engine and cabin battery. Cabin lights and water pump are off the cabin battery, of course.

[smileypete]

(If anyone can link to a documented case where a person was electrocuted from an 30mA or less RCD protected circuit, please do so!!!)

No offers???

 

In the case of a typical sized steel hulled narrowboat in fresh water an RCD will *probably* trip in the event of a full live-earth fault even if the earth is not bonded to the hull. Note the word "probably". There is no *certainty* that it will trip as it depends upon the conductivity of the water, the distance from the side/bottom of the canal, the depth of water, the condition of the underwater painting/blacking etc.

OK Gibbo,

 

What in your opinion is the probability the RCD will trip? 50%? 90%? 99%? 99.9%? What sort of figure do you have in mind?

 

cheers,

Pete.

[chris w]

What in your opinion is the probability the RCD will trip? 50%? 90%? 99%? 99.9%? What sort of figure do you have in mind?

 

cheers,

Pete.

 

Let's suppose you have a loved one Pete (eg: child, partner, parent etc) and your loved one was asked to take part in an experiment whereby, whilst standing on the shore, they were told to hold hands with a person standing on the boat from which the hull earth bond has been removed. Via some means, the live is then connected to the hull simulating a fault..................

 

What, in your opinion, is the probability you would agree to this experiment? 50%? 90%? 99%? 99.9%? What sort of figure do you have in mind?

 

Chris

[Gibbo]

No offers???

OK Gibbo,

 

What in your opinion is the probability the RCD will trip? 50%? 90%? 99%? 99.9%? What sort of figure do you have in mind?

 

cheers,

Pete.

 

For someone who occasionally comes across as quite bright, on this point you are stubborn almost to the point of complete and utter stupidity.

 

I suggest you have a look here....

 

http://en.wikipedia.org/wiki/Electric_shock

 

Note:-

 

5mA = maximum current which should be harmless.

10mA to 20mA = Sustained muscular contraction. "Cannot let go" current.

 

IE EASILY ENOUGH TO PARALYSE A SWIMMER.

 

Then do some googling and see if you can find the reason why US GFCIs are set at 5mA

 

Ok Ill just tell you. It's because 5mA was the maximum current any of the human guinea pigs could tolerate and still be able to swim. Anything higher paralysed them so they sank. If a human sinks, they usually drown.

 

One day you will either accept the dangers of electricity and water or you'll kill yourself or someone else.

 

Gibbo

[tomsk]

For someone who occasionally comes across as quite bright, on this point you are stubborn almost to the point of complete and utter stupidity.

 

I suggest you have a look here....

 

http://en.wikipedia.org/wiki/Electric_shock

 

Note:-

 

5mA = maximum current which should be harmless.

10mA to 20mA = Sustained muscular contraction. "Cannot let go" current.

 

IE EASILY ENOUGH TO PARALYSE A SWIMMER.

 

Then do some googling and see if you can find the reason why US GFCIs are set at 5mA

 

Ok Ill just tell you. It's because 5mA was the maximum current any of the human guinea pigs could tolerate and still be able to swim. Anything higher paralysed them so they sank. If a human sinks, they usually drown.

 

One day you will either accept the dangers of electricity and water or you'll kill yourself or someone else.

 

Gibbo

 

Why dont we see lots of dead fishys and suchlike? And I would like to meet the geneticist who has created a human guinea pig, Crivens isnt science wonderous!!

[Guest]

Why dont we see lots of dead fishys and suchlike? And I would like to meet the geneticist who has created a human guinea pig, Crivens isnt science wonderous!!

My dog eats 'em all.

[smileypete]

(If anyone can link to a documented case where a person was electrocuted from an 30mA or less RCD protected circuit, please do so!!!)

STILL OPEN TO OFFERS!!!

 

Found some information last night on the draft proposals for marina/moorings wiring standards:

 

http://www.iee.org/Publish/WireRegs/Wiring...r_locations.pdf

 

Quote:

 

"Socket-outlets and circuits supplying leisure craft and houseboats

 

Each socket-outlet should be individually protected by (i) an RCD with a rated residual operating current not exceeding 30 mA which disconnects all poles, including the neutral conductor and (ii) an individual overcurrent device. Where a houseboat is permanently connected by a means other than a socket-outlet, once again an all-pole 30 mA RCD and an individual overcurrent device should be used to protect the circuit."

 

Why do they specify 30mA RCDs if they are unsafe? Surely a damaged shoreline could leak a few milliamps into the water and electrocute a passing swimmer? (Go get 'em Gibbo )

 

 

Personally I am more than happy to live on a boat with an 30mA RCD protected shoreline supply and 30mA RCD protected shore power inlet and no hull-earth bond whatsoever. I would be more than happy for any loved one or relative to live in the same circumstances!!!

 

cheers,

Pete.

[Gibbo]

Personally I am more than happy to live on a boat with an 30mA RCD protected shoreline supply and 30mA RCD protected shore power inlet and no hull-earth bond whatsoever. I would be more than happy for any loved one or relative to live in the same circumstances!!!

 

cheers,

Pete.

 

http://www.smartgauge.co.uk/earthing.html

 

<quote>

 

1. The matter of safety for those on board and for those not on board. The matter of safety for those not onboard is often overlooked or completed disregarded by the uninitiated.

 

</quote>

 

More...

 

<quote>

 

The AC electrical system earth should be bonded to the hull because:-

 

1. The European Recreational Craft Directive says so.

 

2. The British Marine Electronics Association "Code of Practice" says so.

 

3. The book "The Boatowners Electrical and Mechanical Manual" by Nigel Calder (a world renowned expert) says so.

 

4. The ABYC (American Boat and Yacht Council) recommends so.

 

How many more references do you need?

 

The above people and organisation didn't come to the conclusion that the ground should be bonded to the hull on a whim. They came to this conclusion because they spent a lot of time and effort studying every possible fault and condition and drawing the conclusion that to bond the ground to the hull is, on balance, far safer than to leave the system floating.

 

</quote>

 

More....

 

<quote>

 

Many people argue that the AC system should not be bonded to the earth conductor (for the reason that it can cause galvanic corrosion problems which we will come to later), but when presented with the above scenario, hold their head in shame and admit that it is something they had never even considered. They had only considered the safety of those on board the vessel.

 

</quote>

 

You would do well to look up Mike Holt who started a one man war in the USA to get the matter of hull bonding and GFCIs sorted once and for all and to prove that retards who think it isn't necessary are wrong. He succeeded when the ABYC made earth/hull bonding mandatory and when the electrical code was ammended to force the use of GFCIs (their term for RCDs).

 

On his site there are details of several deaths attributed to lack of earth/hull bonding. You know about these but shrugged them off as the ramblings of a madman despite the fact that they are all supported by testimonies from the county coroner (ie someone with a degree in medicine) and qualified electrical engineers found the cause in each and every case as being the result of the lack of earth/hull bonding.

 

Gibbo

[RLWP]

Can I just check my understanding on the issue of earth bonding. As I understand it, providing an earth bond means running a bit of suitably sized green and yellow wire to a secure point on the hull? Is that correct? If so, what are the cost and complexity issues around installing such an earth connection?

 

Richard

[carlt]

I think the argument seems to follow this pattern.

 

Smileypete: "It is possible to cross a busy road with your eyes closed."

 

Gibbo, ChrisW, ChrisP, anyone else with an ounce of sense: "Maybe, but it's safer if you open them"

 

Smileypete: "Yes but you don't need to."

 

Everyone else:"But if your option may mean death and ours doesn't, you should open your eyes"

 

Smileypete:"But it isn't necessary, so you might as well keep them shut"

 

Everyone else: "But you might die your way"

 

Smileypete: "But you might not"

 

Everyone else: "But you won't die our way"

 

Smileypete: "That's not the point. You might not die my way"

 

Etc..Etc..ad infinitum......

[Gibbo]

I think the argument seems to follow this pattern.Smileypete: "It is possible to cross a busy road with your eyes closed."Gibbo, ChrisW, ChrisP, anyone else with an ounce of sense: "Maybe, but it's safer if you open them"Smileypete: "Yes but you don't need to."Everyone else:"But if your option may mean death and ours doesn't, you should open your eyes"Smileypete:"But it isn't necessary, so you might as well keep them shut"Everyone else: "But you might die your way"Smileypete: "But you might not"Everyone else: "But you won't die our way"Smileypete: "That's not the point. You might not die my way"Etc..Etc..ad infinitum......

LOL. I think that more or less sums it up.Gibbo

Can I just check my understanding on the issue of earth bonding. As I understand it, providing an earth bond means running a bit of suitably sized green and yellow wire to a secure point on the hull? Is that correct? If so, what are the cost and complexity issues around installing such an earth connection? Richard

Yes that's right. Cost is almost nothing. Wire is quite cheap.It adds the possibility of galvanic corrosion. An isolation transformer will cure this. A galvanic isolator *might* cure this.http://www.smartgauge.co.uk/galv2.htmlGibbo

[chris w]

I think the argument seems to follow this pattern.

 

Smileypete: "It is possible to cross a busy road with your eyes closed."

 

Gibbo, ChrisW, ChrisP, anyone else with an ounce of sense: "Maybe, but it's safer if you open them"

 

Smileypete: "Yes but you don't need to."

 

Everyone else:"But if your option may mean death and ours doesn't, you should open your eyes"

 

Smileypete:"But it isn't necessary, so you might as well keep them shut"

 

Everyone else: "But you might die your way"

 

Smileypete: "But you might not"

 

Everyone else: "But you won't die our way"

 

Smileypete: "That's not the point. You might not die my way"

 

Etc..Etc..ad infinitum......

 

Well done Carl - the most I have ever laughed (in agreement) at a post.

 

SmileyPete now reminds me of straws and clutching................. he's actually never stated why he's so against earth bonding.............. other than it may thwart his suicidal tendencies.

 

Chris

[carlt]

he's actually never stated why he's so against earth bonding.

 

Chris

Heavy investment in portable defib apparatus?

[bottle]

Carl

 

I to cannot stop laughing, thank you.

[Nine of Hearts]

Can I just clear up a couple of things?

 

I've got a 30mA RCD and an hull earth bond and I touch a live wire. The RCD "sees" the discrepancy between the live and neutral, and trips.

 

I've got a 30mA RCD and no hull earth bond and I touch a live wire. Nada, as I'm not earthed. I then decide to touch a small child (it's always a small child in these scenarios) on the bank. The current runs to earth and we are both reduced to a pile of ash.

 

How come the RCD only detects the current loss in the first case, and where is the current going, if not through me? Are earth grounded systems touch sensitive?

 

Don't get me wrong, I'm grounding my system, but I think there may be a bit of overstatement going on. Like entire parties of swimming children being frazzled by a passing boater boiling his badly wired kettle.

[ChrisPy]

Can I just check my understanding on the issue of earth bonding. As I understand it, providing an earth bond means running a bit of suitably sized green and yellow wire to a secure point on the hull? Is that correct? If so, what are the cost and complexity issues around installing such an earth connection?

tuppence ha'penny.

might be difficult to find a piece of wire and a green/yellow sheath and some crimp connectors though, unless you fancy a trek out to your local B&Q.