Plugged into hook up all the time ?

[Matt341]

Hi All,

On our current marina berth there is a lack of hook up points and we were told that to keep the only spare hook up that is infront of us for our use that we should plug in all the time so nobody will pinch it.

I wouldnt want to keep anything on inside and where the plug connects in the cockpit, the wire from the inlet on the boat then runs about 5 inches and into a switch (like a light switch), then it goes to the trips etc. If I was to keep it connected all the time I would make sure this switch was off so no power would be going to the charger or any sockets in the boat.

By doing this will I still need a galvanic isolator? Will there be any problems with the underwater gear?

Also don't know much about this sort of thing but I was told that the marina have a very sensitive earth leakage system so any problems and it trips.

I look forward to your advice.

Many Thanks
Ian

 

[amadeus]

As a non marina user it sounds daft to me that in a situation with a shortage of powerpoints you would hook up unnecessarily. Isn't that just selfishness? If you all agreed only to hook up when you needed power there wouldn't be a shortage! And you wouldn't have the worry about the galvanic problems either. Why not talk to your neighbours about it?

 

[VicS]

If you are plugged in all the time and your incoming earth is connected to the ship's earth and anodes then yes a galvanic isolator is very likely to be required, regardless of what is switched on. (Not if the incoming earth is not connected to any of the boats own systems or anodes though.)

would one of THESE solve any problems

 

[Matt341]

Although it sounds sellfish it was what we were told by the marina office. The boat on the berth before was plugged in all the time and we were told that the others found alternatives and had longer cables etc.

If we didn't plug in they would then use the point infront of us when they have a long cable and we don't.

I am just following advice from the marina office.

Ian

 

[MoodySabre]

Make up a Y-lead or buy one of these so that you can still plug in even if someone else has beaten to the socket. Plugging in if you don't need to is a waste of time and effort and just deprives visitors of a supply.

 

[Matt341]

HI thanks for the replies,

There is a pile infront of the hook up box so only enough room to just get the socket in. I asked the marina whether one of those 3 way splitters could be used, if so I would have got one at my own expense, but the hook up is 13amp and 3 vessels connected would have 4.3 amp connection which would overload even with just a calorifier on.

The mains system is not earthed to the ships system. So by connecting up it shouldn't cause any problems?

Thanks
Ian

 

[Matt341]

Also, the pontoon is residents only and no visiting vessels are allocated on the leg.

I would rather make things obvious from step 1, if someone came down in the week, plugged in and left it and we then had nowhere to plug in on the weekend I would have to unplug the vessel connected to our point therefore causing fridges to defrost etc.

Ian

 

[photodog]

Ours shore supply is plugged in whenever we are in the berth... but I disconnect at the boat when we are not on board. In theory there is now a power point for each berth after they added more points last year.... so I dont view this as selfish.... IMO we pay xxx per year for a berth with power.... and as a resident I shouldnt have to be farfing around every time we show up to access this power...

 

[Matt341]

Hi,

So just to confirm do you leave the berth end plugged in all the time but disconnect from the boat? Where do you leave the live end?

We pay XXXX a year plus we had to buy an electric meter for £130 and we then pay X amount per unit plus a service charge.

I forgot to mention that we were also told to try and keep the boat plugged in as it is easier for them to read meters as we dont have to be called to give the reading etc.

Thanks
Ian

 

[oldsaltoz]

What a shambles. I would have to look very hard to find any marina here that dose not an outlet for each berth. You blokes must spend a fortune on 'Y' connectors and meters that get knocked off from time to time. Oh, no meters on berths here either.

Avagoodweekend......

 

[Matt341]

Usually it is a socket to every 4 boats and they assume that only 1 in 4 will be in use at a time which is silly because in the winter most of the boats on the leg have dehumidifiers.

Even worse is because we are close to the hammer head the sharing is more like 1 in 6.

Ian

 

[William_H]

Hi Brian most mari9nas around here are actually Yacht Club owned and as you say there is no metering of power used. As a member and not a berth holder I suspect I am paying for berth holders to waste electricity.
Things like fridge and freezer running 24/7 and battery charging and I have even heard of diesel engine oil warmers on 24/7.(but not living on board) If these people had to pay for the electricity they use then I reckon they would rethink.
It might also just go towards reducing carbon footprint so saving the planet. (maybe) olewill

 

[Mrnotming]

If you boat has an s drive leg be very careful about leaving her or it plugged in all the time. Serious damage can result to the leg or propellor especially if it is aluminium. A galvanic isolator will help, an isolation transformer is another way to go. Metal pilings nearby or another boat somewhere nearby with a fault can start the process of ion transfer between metals.Big subject, because of which I have gone for solar panels now whilst away from boat and leave it unplugged. good sailing to all.

 

[VicS]

Just to add to paulclans's comments. A galvanic isolator should protect against purely galvanic sources such as the steel piling or nearby steel boats as it blocks such low voltage sources. If electrolysis is resulting from a fault in the wiring of another boat then the GI will not help because that will be driven by a higher voltage (12volts) than the GI is capable of blocking.

I also understand that switch mode power supplies, such as those in modern battery chargers, can also lead to a situation in which a GI is rendered ineffective unless it also incorporates a capacitor!

No problems of course if the shorepower earth is not connected to the ships earth but whether or not that is acceptable rather depends upon which standard you are reading.

 

[James_Hortop]

If you run shorepower onto the boa, you must connect the incoming AC earth to DC negative. This is an absolute safety must.

If you don't do this, any AC finding its way into the DC system (for example through a faulty charger or chaffed cable), you could end up with your DC system floating at 230V and the shore RCD not tripping. The issue is that then your DC system (and perhaps underwater metal parts of the boat (if connected properly), are then hooked through the earth wire back to the pontoon (as the pontoon will be bonded)). This is why a Galvanic Isolator is required.

Never heard of the issue with battery chargers requiring a cap on the input? Where did this info come from?

James

 

[VicS]

Regarding the connection between shorepower earth and the boats earth/ Dc negative. According to ISO13297 :

4.2 The protective conductor shall be connected to the craft's d.c. negative ground (earth) as close as
practicable to the battery (d.c.) negative terminal.
<span style="colorurple">NOTE If an RCD (whole-craft residual current device) or an isolation transformer is installed in the main supply circuit of the a.c. system (see 8.2), the negative ground terminal of the d.c. system need not be connected to the a.c. shore ground (protective conductor). </span>

I am aware though that other standards, ABYC for example, do require the connection, RCD or not!

even if there is a fault of the type you suggest the current flow to earth via the underwater bits and pieces should trip the on board RCD. In any case the RCD gives protection from electrocution (except from direct contact with both live and neutral but then nothing helps there!)

The GI only gives protection against galvanic corrosion, caused by different metals (such as iron and steel) becoming connected vi the shorepower earth. It does not protect against electrolysis caused by higher voltage sources. Its relevance to the mains voltage power supply is that while blocking low voltages of "galvanic" origin it allows current from high voltage sources to pass thus maintaining the protection of the earth.

Regarding the capacitor. Its a capacitor in parallel with the GI that I refer to not on the input of the charger.
Sorry I cannot remember the source of the info, probably one of your competitors websites!
My understanding is that some switch mode power supplies can put a high frequency AC current to earth which being from a higher voltage source than the GI blocks, can put it into "conducting mode" and as a result allow the current from galvanic sources to pass also.

 

[James_Hortop]

Ok, so if an AC cable cafes through and say, the guard rails sit at +230V and they aren't grounded, will the RCD trip = no. If they are grounded = yes. The same applies for the DC system. If it isn't grounded, it too would sit at +230V until a path to ground is made. If that path to ground is a person, potentially (excuse the pun), that person's life depends on the reaction of the RCD.

The ISO standard you quote is in direct contravention of every engineer I know, every electrical company in the industry, ABYC, UL (who's standards are those that the british and ISO base their standards on) and BMEA.

I've also seen noise from aircon etc cause issues with isolators etc. Sometimes, the noise level has been in excess of 30mA causing RCD's on the shore to trip. Only normally a problem on bigger boats or with very big chargers - in the case of switch mode power supplies, their EMC levels conducted on the Earth wire should be controlled. If we see this type of case, we would normally recommend an isolation transformer.

James

 

[Refueler]

In the marina I was - we had similar where there were not enough sockets for boats. But because we paid for electricity meter connected in the socket ... we had a key and lock to close of power socket when we were not there. basically we paid for a service and were entitled to demand it's exclusive use at point designated as ours. If you didn't pay for the metered supply - then you had option of long cable to a shed at top of pontoon on land to connect to a communal slot meter supply.

I think I would be a bit p'd off paying out so much for a meter and then not able to connect !

Are you saying that even though there are not enough sockets for boats - the marina is selling out meters to anyone who wants - even if no of sockets are less ?

There used to be a plug that was lockable into a socket - without lead etc. It prevented others connecting - designed for integral metered sockets allocated to a person.

 

[Bilgediver]

Ok, so if an AC cable cafes through and say, the guard rails sit at +230V and they aren't grounded, will the RCD trip = no. If they are grounded = yes. The same applies for the DC system. If it isn't grounded, it too would sit at +230V until a path to ground is made. If that path to ground is a person, potentially (excuse the pun), that person's life depends on the reaction of the RCD

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You are falling into the trap of so many here....You are not taking into account the variables that exist.....

Is the marine on a bonded earth system or not...does the marina have separate live neutral and earth does the marina have isolation transformers.

does the boat have bonded earth and neutral .. does the boat have an isolation transformer....and in your case above....does the boat have BONDED guard rails which is something I have never seen on a glass fibre boat.

The regulations for marina electrical supplies was very loose until recently however it is now written up and calls for non bonded earth/neutral or isolation transformers however how many marinas are connected as we would hope.

Before we go randomly connecting earths to DC negative I for one would like to know what is going on ashore.

If I have isolation transformers then in your situation I wonder if there would be protection. as the guard rails aren t bonded either.

Earth is to a keel stud remote from DC

Moreover in the Marina Regulations they show that a boat earth to an immersed metal point is required however they do not suggest this is linked to the DC neg.....