Counting The Cost Of Shore Power

[Nausikaa]

NAUSIKAA's shore power system has been pretty basic. Until now it has consisted of a simple extension cable of the type found in any garage or handyman's kit (in fact, it was even the simplest of them) which was fed into the boat through one of the hatches to power the electric kettle (often), power tools (from time to time), computer (frequently), an electric heater (much needed this summer) and my youngest son's cruising essential - a Nintendo DS. On very rare occasions it even charged the service battery.

As I have a basic desire to have the best possible equipment and to be legal I thought I would invest in the propper kit for shore power. This resulted in an internet order to a company in the north of Sweden. I will gladly name the company - Hjertmans - as they provided an excellent service. The goods arrived yesterday in perfect order so I look forward to the actual installation job.

What I bought was a shore-power system panal board comprising of double circuit breakers and a double RCD-breaker, a Marinco inlet in stainless steel (classy) and 25 metres of marine grade extension cable with a Marinco fitting on one end and a European CEE contact on the other. Once set up I should be legal according to EU rules. I should also have a simple but sound 220 volt system.

As for the cost, the whole lot was about Euro 380. My existing extension cable cost Euro 32 and has done the job well. Being legal does not come cheap but at least I know that I will have a good system once installed.

Reflecting over the cost prompts me to ask the question, how far are we prepared to go and pay to be legal? Many cruisers are operating on a very tight budget, others have the cash to spend but the vast majority probably lie between the two extremes so when does the average cruiser say, "s*d it, I am not going to pay for that." Obviously, it is a question of priorities but how far will YOU go in order to be legal? Do you have some areas where you are willing to pay to be legal and others where you are not?

Aye

Stephen

[redbopeep]

Originally Posted by Nausikaa

Reflecting over the cost prompts me to ask the question, how far are we prepared to go and pay to be legal? Many cruisers are operating on a very tight budget, others have the cash to spend but the vast majority probably lie between the two extremes so when does the average cruiser say, "s*d it, I am not going to pay for that." Obviously, it is a question of priorities but how far will YOU go in order to be legal? Do you have some areas where you are willing to pay to be legal and others where you are not?

Aye

Stephen

That's a good question. Many times "legal" equates to "safe" anyway so its something everyone does. But, here, you're talking about doing something "to code" as we say in the US building trades. Many times "to code" isn't about safety it is about labor unions or companies rights to exclusively sell things, or to minimize liability etc.

In the posting about saving music to our hard drive--well, its not actually "legal" for the average Joe to make an mpeg. But we all do it. Or, if you own an LP, in the US you actually cannot legally copy it to a tape or your computer--you're supposed to buy another copy. Those are foolish "legal" things that are all about a company's rights to exclusively distribute/sell things. I will buy a copy of something instead of getting it for free from a friend. But, these other things. No, they're silly.

The same goes with certain building codes that are all about protecting the business/job of a particular tradesperson (plumbers, etc). Those codes seem a little closer to being safety related though. We installed our own alarm system in our house--because there was a racket where only certain installers could "legally" do it--and the code test they had to take to be "legal" in DC hadn't been offered for 13 years when we needed an alarm installed--so no new competition could "legally" install alarm systems. Prices were high, we just did it ourselves--wasn't legal but it was safe. We also redid all of our plumbing and wiring--because we knew what we were doing and knew that our work was of a higher quality than the average tradesperson who was "legal" to do it to code.

On the boat, we do everything we can do to be "safe". We usually don't think about "legal". However, we've had a surveyor out looking at both the 30' boat and the larger one one under reconstruction--he always tells us what is needed to meet insurance company requirements and be safe--i.e. double hose clamps, things like that. On the rebuild, there are some scantlings that we're paying very close attention to doing per established standards (lloyds, etc) to make sure that we're safe AND importantly insurable.

When we're dealing with shore power, or charging batteries, or anything electrical, my husband usually goes above and beyond the recommended practice because he's an EE (electrical engineer) by degree and has an amazing understanding of all the things that can go wrong. We're always way beyond what anyone else would do in terms of safety systems, control systems, etc. He's just not comfortable otherwise. Want to hear the stories about every time we moved how he'd take all the electrical outlets apart to make sure they were wired properly? Really. Every rental apartment, everything. And, sometimes they weren't wired right or the breaker is wrong or something. We're the only people I know who'll be buying electrical parts and installing them in an apartment we don't own because he's not comfortable with the status of the electrical system. Want to know that we have line conditioners on things like the refrigerator? UPS/line conditioners on every piece of stereo equipment, computer, etc. We're just over-the-top when it comes to electrical things. Most people have one line conditioner for their computer--we've got 10's of line conditioners...

Yep, he traced all the wiring on the 30' boat to make sure it was good. Replaced several things. Yep, we traced all the plumbing lines too. Replaced several things.

Just because something is "legal" isn't the reason to do it, IMHO. You should do it because its safe, or for another reason that is clearly understood and that you value. If the requirement is there for no reason than being a "rule", then, no I wouldn't do it either.

my 2 cents worth

[Auzzee]

This is very interesting and is something about which I have given no serious thought. I know the 240V set up on Belinda was installed by a licensed electrician. I have the schematics along with his inspection certificate.

But, I do not know what the requirements are for a 240V system, on a boat, which can be connected to a mains supply. Now I shall have to find out.

David.

[Nausikaa]

Originally Posted by Auzzee

I do not know what the requirements are for a 240V system, on a boat, which can be connected to a mains supply. Now I shall have to find out.

David.

This is an interesting point as if I was to visit you in Australia then NAUSIKAA could connect to the Australian grid but would, being a foreign vessel, not be subjecty to Australian installation requirements and vica versa. Flag state rules apply.

Aye

Stephen

[Nausikaa]

Originally Posted by KiwiAussie

However, there's plenty of opinions in regards to using a high quality isolation transformer when connecting to shore AC (of which you may already have) & using full electrical bonding (for complicated electrical systems & to reduce the risk of shock).

Indeed! I was just looking at this issue earlier today. The problem seems to arrise in complicated electrical systems and with battery chargers. Newer marine battery chargers have automatic RCD breakers which cut the circuit if a current of 30mA is detected for a period of about 20milli seconds. My charger is a completely new marine charger so I am safe on that front. Appart from the charger there is nothing connected to the electrical system which is not double isolated and for which no earth (ground) is required here in Scandinavia.

I think I am safe without the isolating transformer but am willing to listen to good advice there.

The great advantage, besides safety, with a transformer is that they can cope with varying voltages. My AC equipment runs on 220 - 240 volts at 50 Hz. If I go to the U.K. I get the same voltage but, I believe, 60 Hz. Go even further westwards, accross the Atlantic to Canada and the U.S., and I will get 120 volts. There are transformers which can cope with this and give me my normal 220 volts on the boat.

For me electrics is black magic. I do my best to have good electrics in the boat. I can read a circuit diagram and install equipment according to that diagram. I even built a valve amplifier many years ago (and it worked) but understanding elecricery is a different matter. I think I will spend the rest of this evening studying Nigel Calder's "Boatowner's Mechanical and Electrical Manual".

Aye

Stephen

[Auzzee]

Stray electrical current is a major issue, particularly for boats which are left for long periods unattended, but with shore power still connected. Last year, a fabricating team was building a new anchor roller/bowfitting on a vessel tied up adjacent to mine, and had an electric welder in operation for about four hours. The anode which I have bonded and hung over the stern especially for marina galvanism, dimished noticably in size in the space of the few days surrounding the welding work.

I don't understand the physics of stray current, especially in regard to sufficient amperage in the water between vessels to cause electrocution, but given the fatal nature of high amp exposure, it always concerns me.

It is just one more reason why, when I move aboard, I shall endeavour to anchor off the beach rather than tie up at a marina. Here's an interesting link to the 'Corrosion club' http://www.corrosion-club.com/index.html

David

[Nausikaa]

I have spent much of the past 24 hours studying the requirements for a 220volt shore power installation, i.e. European standards.

What I have concluded is:

a. there is no REQUIREMENT to fit an isolating transformer, see ISO 13297:2000. The Recreational Craft Directive of the EU refers to this a a "harmonised standard". Confusingly the Recreational Craft Directive is refered to as the RCD but in terms of electrics an RCD is defined in ISO 13297:200 as a Residual (differential) Current Device. What then is an RCD (electrical) ? It is simply another term for GFCI or Ground Fault Circuit Interupter.

b. Nigel Caulder recommends fitting an isolating transformer, see his comments in Yachting Monthly here

c. These standards are EU standards and certainly differ from those in the US, Oz, RSA and other parts of the world

d. If an isolating transformer is fitted the boat's electrical system must be earthed/grounded using a grounding plate on the hull.

Now, I have a problem with the fitting of an earthing/grounding plate and isolating transformer. If the boat is on the hard or at a drying out berth then when the water level is below the earthing/grounding plate the boat sill not have an earth/ground. Obviously this can be fixed by drawing a conductor of suitable dimensions from the earthing/grounding plate to a suitable earth/ground point, e.g. a metal rod firmly implanted in the soil. But how many people remember to do this? On large ships when in dry dock and shore power the ship is earthed/grounded by a huge copper wire but I don't recall ever having seen an equivilent on small recreational craft.

For reference, ISO 13297:200 can be found here and the European Recreational Craft Directive here

Confused but begining to see the light

Stephen

[Nausikaa]

Originally Posted by KiwiAussie

A safe way may be to disconnect the house/service/engine batts when on the hard. If not just for normal grounding issue's but also lightning strikes.

Indeed, you are probably quite correct there but my point is how many cruisers actually do this or create a functional earth/ground?

Aye

Stephen

[Auzzee]

Here I go displaying my ignorance of things electrical again!

I don't understand the need for independent grounding when on the hard stand. If connected to 240v mains power, the law requires that it is return grounded to the grid system. Surely that is the reason we have three-pin plugs.

Also, it is my understanding that in Oz, it is illegal to install a system that will be connected to 240v mains, unless it incorporates a residual current device.

Cheers

David.

[Nausikaa]

Originally Posted by Auzzee

I don't understand the need for independent grounding when on the hard stand. If connected to 240v mains power, the law requires that it is return grounded to the grid system. Surely that is the reason we have three-pin plugs.

OK, my understanding (wrong verb really as it implies that I understand matters electrical - which I don't) is that if you have no isolating transformer fitted then, when on the hard, the grid's earth/groung will be protecting you in just the same way as it does someone in an AC fitted caravan/mobile home/camper etc. No problems with that.

The problem arrises when the AC is fed into a boat with an isolating transformer.

The question then arrises; why fit an isolating transformer? The isolation transformer serves four functions:

* Firstly, it eliminates all hard-wire connections between the boat and the shore and other nearby boats thus significantly reducing galvanic corrosion.

* Secondly, an isolation transformer with multi input and output voltages can be used to produce 120/240 volts from either a 120 or a 240 volt source.

* Thirdly, a multi-voltage isolation transformer can boost low input voltage to a more acceptable level.

* Fourthly, as the polarity of the AC system on board is established at the transformer then, should the polarity ashore be reversed for some reason, the polarity on board will remain un-altered.

A futher advantage of an isolating transformer is that it protects you on board AC system from surges, spikes and transients.

Note: an isolation transformer produces both heat and noise and must therefore be installed in a well-ventilated location.

So, having been convinced of the need for an isolating tranformer we have fitted one in the boat. The primary side of the transformer is connected to the shore grid and earthed/grounded using the grid's eart/ground. The secondary side of the transformer has no physical connection with the shore grid and so

the neutral and earth/ground are bonded on the output side of the transformer. This recreates exactly the same sitution as we normally receive from the national grid and is what allows fuses and RCDs to operate in the correct manner. There is also a "safety screen" between the primary winding and the secondary winding which is connected to shorepower earth. This is so that any fault current in the primary (for instance from insulation breakdown) is returned to shorepower earth to trip the circuit breaker or RCD rather than electrifying the boat hull.

One other point should be made regarding isolating transformers and baots that venture away from their normal cruising areas. In the US the standard AC is 110 volts at 60 Hz. On mainland Europe voltage is different but so is the frequency. Here we use 50Hz. The isolating transformer will, if it is the multi voltage type, give you your normal on board voltage but the frequency is that of the "host" grid. For many bits of equipment the difference is of no importance. My laptop, for example, is perfectly happy running at either 50 or 60 Hz. Other equipment, such as microwaves, are not so happy about frequency changes. If you plan on a voyage to areas with different frequencies then check that your equipment can cope with the change.

So, the sum of all this is that I basically understand the system for a boat in its right element but, once removed from that element and standing ashore is there a need to earth / ground the boat's AC system to the shore? I honestly don't know. If there is anyone out there who can give us the answer then please do.

Finally, I have discovered that European & US practices differ widly here. In Europe the transformer is favoured where as in the US the use of a galvanic isolator is common.

I am trying hard to understand this electickery thing. If there is anyone reading this thread who has a good understanding of AC ionstallations on board then please share your wisdom with us.

Aye

Stephen

[Auzzee]

Thanks Stephen, it will take me some time to digest your post, but it all helps toward my education.

David.

[Nausikaa]

I have, I think, solved the problem.

When reading Victron Energy's instructions for fitting their isolation transformer they show in a diagram that when the boat is afloat the shore earth/ground connected to the transformer but isolated from all else on board. They advise that when the boat is ashore for lay-up or any other reason that the earth be connected "for safety reasons" to the vessels own earth. In their transformer this is done internally.

Hope this clears things up

Aye

Stephen

[Nausikaa]

Originally Posted by KiwiAussie

How is the vessel earthed when its on the hard??? (i.e. the copper grounding plates are not in contact with salt water). Does the transformer automatically use the shore AC earth?

PS. Apologies if I've misunderstood your post

Sorry...my bad English

They advise that when the boat is ashore for lay-up or any other reason that the earth be connected "for safety reasons" to the vessels own earth. In their transformer this is done internally.

What I mean by that is that the grid earth in the primary section of the isolating transformer should be connected to the earth on the secondary side which, under normal circumstances, is the vessel's own earth. By doing so, the vessel's earthing system is then conected to the grid's earth.

Hope that explains it.

[Auzzee]

So, providing the vessel is connected to a normal, reliable grid, is the primary benefit compatability, or protection?

David.

[Nausikaa]

Originally Posted by Auzzee

So, providing the vessel is connected to a normal, reliable grid, is the primary benefit compatability, or protection?

David.

Without a doubt, the primary benefit is protection against galvanic corrosion. Doesn't come cheap though. Despite that, I have decided to go all the way and invest in a complet, although simple, AC system.

Aye

Stephen

[Auzzee]

Hi Stephen,

Please will you (and any other like minded souls) check the following for me. http://www.marinedirect.com.au/catal...0/product57929 This link is to a Galvanic corrosion and electrolysis protection device which costs AU$345. Is it in your opinion worth the money and do these devices genuinely offer a high degree of protection?

Thanks

David.

[Nausikaa]

Originally Posted by Auzzee

Is it in your opinion worth the money and do these devices genuinely offer a high degree of protection?

Hi David,

Thanks for posting this. I have had a good look at what little there is to read about this "electrolysis blocker". My take on this is that there is no decription of what this piece of kit actually is but I believe it to be a galvanic isolator, sometimes know as a zinc saver.

A galvanic isolator and an isolating transformer are two different bits of kit. I will try to explain this using information from a Swedish book called, "Elsystem för Båtar (Electrical Systems for Boats) by Magnus Sterky.

A galvanic isolator is designed to hinder the low voltage currents which cause anodic corrosion and the high rate of consumption of zinc anodes.

In its simplest form a galvanic isolator is two diodes connected in parallel but in opposite directions so that current can flow in either direction. The galvanic isolater is "plumbed in" between the protective earth of the grid (shore power) and the boat's earth. The diodes allow current from a short circuit to flow which will then blow the circuit breakers. On the other hand, the pure galvanic potential differences of very few volts will be blocked by the unit.

Galvanic isolaters are good pieces of kit in the right places. The AYBC recommends their usage. However, and here is the crux, they will not be as effective some parts of the world as in others. The reason for this is that the ground (by this I mean the rocks, silt, sand and soil we stand on) is more or less conductive. Here in Scandinavia we have a problem as mountainous areas composed of crystilline rock types are poorer conducters than say a clay valley. In other words, the greater the amount of crystaline strata the greater the resistance. Here, in Sweden, the resistance is about 100 times greater than that of continental Europe. I can immagine that similar differences can be the case between say, British Colombia / Washington State and the Gulf of Mexico.

Now, to continue, when electricity is "delivered" it comes in three phases, although we are probably only connecting one phase to the boat. The other two phases are connected to other users. As electrical consumption on each phase will not be identical a phase inbalance is created. This creates a problem as the high voltage, three-phase current is transformed down to 220 volt and to create an earth the earth wire is connected to the neautral at the transformer. Now, to take it further, at the marina we also have an earth but this earth is a little distance from the earthed transformer and - here comes the important bit - because of the different rates of power consuption on the different phases, which results in the phase imbalance, the middle point of the neautral at the transformer will actually vary in voltage. As you will remember, the earth wire is connected to the neutral at the transformer which will therefore result in a flow of current to earth at the transformer. When this happens there will also be a voltage difference between the earth at the transformer and the earth at the marina but, as we have connected to the earth at the marina there will also be a voltage difference between our boat and earth. This will give rise to corrosion problems onboard.

Now, back to the mountains. As the crystaline areas are better insulators than the clay soils then a greater current will be required to overcome the resistance than in clay soils. This means that the small currents necessary to create galvanic problems when connected to a common ground will need to be much higher to have the same effect. The galvanic isolator works on very small currents and thus is unsuitable for areas such as this where a larger current is required to create galavic corrosion when connected to a common earth.

An isoating transformer seperates completely the boat electics from shore power and, as the current used on board is generated in the output side of the transformer, there can be no voltage inbalance.

The bottom line here is that galvanic isolators are not recommended in Scandinavia, not because they do not work but just because they do not work HERE! Isolating transformers are recommended HERE!

I know this does not answer your question David but I think you have to work out which are your potential cruising areas. If you will be hovering arround the Far East then I am sure a galvanic isolator will be a good piece of kit to have but if you plan on visiting the fjords of South Island or Chile then an isolating transformer would be a better bet.

Sorry about the complicated and difficult explination. I am no expert on the subject and am trying to understand it myself.

Aye

Stephen

[Auzzee]

Hi Stephen,

Thank you very much. Your explanation is far more easily understood than anything else I have tried to comprehend. It provides me with the means to make an informed decision.

Thanks again,

David.

[MMNETSEA]

Hi David ,

This site is extremely informative - although specifically directed to the US boating industry.

http://www.uscgboating.org/safety/boatbuil.../electrical.htm

Richard