110 out of 220?

Discussion in 'OnBoard Electronics & Controls' started by tropicalbuilder, Aug 30, 2012.

  1. bpw
    Joined: May 2012
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    bpw Senior Member

    Multi-phase AC has more than two wires.

    Like I said before, my brief education in all this did little more than show me how much more complicated AC wiring is than I ever would have believed.

    Anybody want to talk about power factor?
     
  2. tropicalbuilder
    Joined: Jun 2010
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    Location: costa rica

    tropicalbuilder Junior Member

    ok the situation here in mexico is like the US, we have 240V two phase that is split to 110V single phase for normal use.
    110V (black) , neutral(white) ,ground(yellow/green) .
    Now if you take the two 110V single phase and use them together you have the 220V.

    This is the way my boat is receiving power from shore from the 110/220 50Amps outlet of the marina - 110V (one phase) 110V (one phase) and ground.

    My original question was:
    is it ok to make a 110V outlet to use power tools and appliances (drills, TV, blender..)
    just taking one of the phase (110V) on one side and the ground on the other?
    Or should I use a dedicated shore power line and bring 110(one phase) neutral and ground and connect this to the outlet I want to use?

    According to PAR that says that in the USA, the green wire (ground) and the common wire (white) are attached the same bus in the panel it looks like there is no difference in using either the green or white wire to provide the return path to the phase.

    Is it correct?
     
  3. jonr
    Joined: Sep 2008
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    jonr Senior Member

    Your first option will work if you address the below issue. I recommend using a GFCI outlet.

    The ground is there for safety and you always use the neutral as the return path. So you should be using 4 wires from the marina (+120, -120, neutral, ground). Ground isolation and GFCI protection for the entire supply circuit are other issues to address.
     
  4. CDK
    Joined: Aug 2007
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    CDK retired engineer

    No, certainly not in this forum!
     
  5. Grey Ghost
    Joined: Aug 2012
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    Grey Ghost Senior Member

    I'm not an electrician, but I don't think it is safe to use the ground wire as a neutral.
    http://www.highport.com/electricalHazard.php
     
  6. CDK
    Joined: Aug 2007
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    CDK retired engineer

    Certainly not!
    The yellow/green is supposed to save your life in case of an insulation failure. It is internally connected to the metal parts of your appliances, if somewhere along the line a bad contact develops, using it as a return causes all these parts to become live.
     
  7. Frosty

    Frosty Previous Member


    And all the other boats live too. Skin fittings melting, propellors disappearing, its happened here.

    Which is why I don't use earth,-- all my appliances are 2 pin plugs on plastic framed appliances.

    And I dont have a bonding system for the same reason. I dont want be some sacrificial anode for some one elses mistakes.
     
  8. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    So you have an frq/voltage converter running the whole boat on 220V 3 wire and you want to tap the incoming 120/240 split phase 4 wire, correct? or do you only have a transformer w/o freq conversion?

    I think the best solution would be to bring a new 30A 3 wire 120v lead onboard and distribute that separately for convenience tool use. I don't think I'd bother with the galley, just use Euro appliances.

    I'm assuming this is intended for owner-not-on-the-boat sort of chores. If the idea is that the owners/guests might use the system, I think I'd just say no thanks. Easier to just have the euro tools; but a PITA that you can't carry them ashore. I don't think the public is really prepared to deal with two AC electric systems. I know Americans aren't.

    Is there an issue with guests bringing gadgets aboard?
     
  9. tropicalbuilder
    Joined: Jun 2010
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    Location: costa rica

    tropicalbuilder Junior Member

    yes i think i will go for the separate 120V shore power and make some dedicated outlets …
    you are right dealing with two AC systems onboard could be a problem with guests.

    Now after all your post I have a big doubt….

    this boat is from europe, with his 220V 50Hz system single phase …
    And here the 220V i can get is two phase 60HZ … can this be a problem for electronic equipment like battery chargers, inverters, Air conditioning, and so on??

    I mean, at the moment everything is working fine …. but is this going to be ok on the long term??

    If not what would be the solution??
     
  10. jonr
    Joined: Sep 2008
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    jonr Senior Member

    As CDK said, motors may not like 60Hz. Other things should be fine. You can buy variable frequency drives to fix the former.
     
  11. philSweet
    Joined: May 2008
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    philSweet Senior Member

    Yes, I'd consider it a problem if you don't have an isolation transformer and the correct neutral taps on each side. Again, it goes towards people's expectations and experiences. A 240,0,ground socket isn't a 120,120,ground socket. Sooner or later someone will find a reason you shouldn't have done this.

    For instance, check the outlet's contact voltages when the branch curcuit breaker is switched off.
     
  12. Frosty

    Frosty Previous Member

    I think your boss thought he bought a cheap boat --maybe he did,-- now you know why.

    Best thing and not so expensive is convert, yes the whole lot.

    Buy all new appliences, use original wiring and change sockets.

    You will get your money back when he sells it.
     
  13. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    It is not so complicated. 220 out of two 110 lines is the standard setup in North America. The outlets are usually in pairs at the dock, one being A phase and the other B phase. The A and B lines together are 220V. The ground (earth) wire is green and the neutral (white) doesn't get used. The hot or powered wires are black, red or dark blue.
     
  14. Frosty

    Frosty Previous Member

    If you twist 2x 110 together your saying you get 220? I hear what your saying but if I twist 2x12V together I still have 12 v.

    I know that if I twist 2x 220 together I still get 220

    I also dont understand how you line up the phases to give 60cycles from 2x 60 cycles you should have 120 cycles.
     

  15. jonr
    Joined: Sep 2008
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    jonr Senior Member

    If you put two 12V batteries in series, you get 24V. Same principal. The two phases are 180 degrees out of phase, so referring to them as +120V and -120V can help.

    If you only want 240V, then you don't need the neutral. But if you want 120V, then you need it (the ground is not a substitute).
     
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