Shore power cord?

Discussion in 'OnBoard Electronics & Controls' started by michigangeorge, Dec 27, 2012.

  1. michigangeorge
    Joined: Dec 2003
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    Location: Petoskey,Michigan

    michigangeorge Junior Member

    I'm starting a total new wiring project on an 18' wooden catboat with a very simple 12v DC electrical system. Charging for the single group 24 battery comes from the inboard diesel or by a Guest Charge-Pro 6amp mounted charger. The charger comes with a 6' three wire 110v lead to plug-in to a shore power outlet.
    My boat has no AC wiring and I do not want to add any if possible. The charger has an optional thru-bulkhead fitting which will securely hold the male plug-in much like a smaller version of a Hubble fitting. This would allow for using just a good quality three wire extension cord to the shore station instead of a heavy,cumbersome 30 amp Hubble type shore power cord. I'm thinking Guest designed this fitting as a simple set-up for a trailer boat sitting in a driveway.
    There is no twist-lock but the extension cord could be easily secured and the plug would be mounted under the cockpit seat overhang so would be somewhat weather-protected but not totally waterproof.
    My question is- how safe is this set-up for dockside use?
     
  2. BertKu
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    BertKu Senior Member

    As long you have the casing of the charger earthed to the shore, but the secondary 12 Volt charging minus/ground part must be NOT connected to the shore, but to the boat earth/ground plate. You will pick up problems with corrosion otherwise. There are a number of threads which addresses this particular problem. I would suggest you search a little. Bert
     
  3. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Sure...why not. You have no ac system and very little draw with only a small charger.

    A outdoor quallity three wire extension cord is fine for the short run to the dock .

    Your problem is the boat end plug. Dont know US style plugs .

    The European style, 16 amp, 3 pin male wall mount connectors on the boat would be nice.

    Be sure that you have some kind of ground on the boat. Electical equipment like the Battery charger case needs to be grounded. .
     

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  4. michigangeorge
    Joined: Dec 2003
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    Location: Petoskey,Michigan

    michigangeorge Junior Member

    Thanks for the quick reply, Bert and Michael. Problem is this little charger is a sealed, waterproof unit in a plastic case. I see no way to provide an external ground.
    www.marinco.com/product/10-amp-dual-battery-chargepro-charger-0
    The 6amp unit only has 2 wires coming out of the case unlike the 10 amp showing here.
    Sorry I'm so dense on this :-(
     
  5. BertKu
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    Location: South Africa Little Brak River

    BertKu Senior Member

    No, No, what you have to do is to measure whether the earth from your 110 V AC is connected to the earth of/or the secondary minus of your 12 Volt. (and at the same time measure whether your metal casing is earthed. If this is connected, you may have to use a diode to isolate the galvanic corrosion problem.
    Bert
     
  6. BertKu
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    BertKu Senior Member

    To understand the problem if you earth your boat's earth to the shore. All the boats in your area will say thank you and all the stray currents will go shore via your boat. I would not like to see, how your metal will look like after a few months. Sorry Michael, I have great respect for some of your contributions, but electronics/electrics is not your strong point.
    Bert
     
  7. Frosty

    Frosty Previous Member

    His battery charger is plastic casing and therefore comes with a 2 wire plug.

    he is right not to mess with an Earth no matter what regs say.

    If the Marina earth is working than ok but what is he earthing --the plastic case.

    If it was a metal case and the Earth in the marinas DID NOT and he had a a fault then he is earthing through the other boats.

    Then if other boats have a grounding system they are earthing your faults, and the prop and skin fittings are melting.

    Regs are great IF they all WORK.

    Every thing I buy is plastic none have a 3 wire cord.
     
  8. BertKu
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    BertKu Senior Member

    I agree , if the transformer is isolated and the primary side has no earth. The plugs shown on the picture from Michael shows 3 pins, thus with earth.

    The question from me to Michigangeorge is as follow.

    Is there any conductive connection with the primary and secondary 12 Volt. If yes, you have to use a diode secondary to lift the stray current level.
    If not, there is no earth and neutral is not connected to the secondary ground/minus 12 Volt. All what you have to do is to make sure the secondary minus 12 volt is connected to the ground plate/earth of his boat. One should not let it float. Bert
     
    Last edited: Dec 27, 2012
  9. michigangeorge
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    michigangeorge Junior Member

    Nope, the charger has a three wire plug but everything but the actual wire is plastic. I guess my concern will be more with the GFI on the dock. AC around the water scares me - seems like I should have additional protection on the boat.
     
  10. BertKu
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    BertKu Senior Member

    Sorry Frosty, don't assume, I had a look at the picture, it does not state 2 or 3 pin primary. Do not assume, but get the facts. Bert
     
  11. BertKu
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    BertKu Senior Member

    Thanks our replies crossed each other. Do not be afraid for AC, although give it some respect. If I am naked, sweaty and I touch AC, I will most likely survive. If I am naked and sweaty and the DC current of 24 Volt goes through my 72 year old heart, I may be a goner. Your unit is earthed primary for static reasons. JUST CHECK, whether you have any connection below 100 K Ohm between the 3 pins and secondair 12 Volt. That is all we need to know from you. Bert
     
  12. Frosty

    Frosty Previous Member

    I did not make the above quote. Please do not post incorrect or altered postings.

    Do not make 'light' of 220 ac it will kill you --72 years old or not


    If its a plastic case then where is the third wire connected to . The earth should be connected to the body but if it is plastic why.

    Even if it were static that s not required on plastic.

    Some countries have 3 pin plugs moulded to the wire by regulation but it can not be of any use on a plastic frame.
     
  13. BertKu
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    BertKu Senior Member

    He has 110 V AC, I have had a number of incidents with 220 V. It is not my ghost writing to you.

    Like I have explained., for static reason. But lets get the facts from George.

    Correct, but you have electronics in the charger, like buck inverter etc. I always ground electronics or ground the isolation grid some transformer manufacturers has between primary and secondary. Even if the casing is potted or from plastic.

    Correct again, but what about the electronics and isolation grid primary/secundair of the transformer in good quality systems? Bert

    Lets get the facts form George and see whether there is any conductivity between primary and secundair. Then we will discuss it further. Bert
     
  14. Landlubber
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    Landlubber Senior Member

    "see whether there is any conductivity between primary and secundair. Then we will discuss it further"...that my friends, is the answer.

    If there is nothing there, go ahead and plug her in, no worries.
     

  15. jonr
    Joined: Sep 2008
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    Location: Great Lakes

    jonr Senior Member

    You should be much more afraid of 120V or 240V AC than 12 or 24V DC. As the manual says, make sure there is a GFCI in the AC circuit.
     
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