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13-06-2015, 07:18
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#1
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Moderator

Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 35,307
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One phase from three phase
Here's a question for you electrical wizards.
I am standing in a commercial port, couple weeks for free (I know the port director).
This port does not take yachts or even fishing vessels, so there is no single phase power anywhere. The smallest power outlet is one of those round ones with 5 pins. I believe that it is 380/230V three phase, with one phase on each of three pins, then neutral, and ground.
So my question: Can I get single phase 230 volt power out of such an outlet by connecting any one of the three phase pins to hot, neutral to neutral, and ground to ground?
I have actually sourced an appropriate plug, so can make an adapter if I've got the electrical part right.
Please advise. Also, if there is any test procedure which you recommend to be sure I've got it wired right. I guess hot to neutral to verify voltage, hot to ground to verify no voltage, right?
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
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13-06-2015, 07:22
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#2
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Registered User
Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,452
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One phase from three phase
Quote:
Originally Posted by Dockhead
Here's a question for you electrical wizards.
I am standing in a commercial port, couple weeks for free (I know the port director).
This port does not take yachts or even fishing vessels, so there is no single phase power anywhere. The smallest power outlet is one of those round ones with 5 pins. I believe that it is 380/230V three phase, with one phase on each of three pins, then neutral, and ground.
So my question: Can I get single phase 230 volt power out of such an outlet by connecting any one of the three phase pins to hot, neutral to neutral, and ground to ground?
I have actually sourced an appropriate plug, so can make an adapter if I've got the electrical part right.
Please advise. Also, if there is any test procedure which you recommend to be sure I've got it wired right. I guess hot to neutral to verify voltage, hot to ground to verify no voltage, right?
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If it is delta connected you will ,likely, not have a neutral.
Are you in the USA?
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Looking for another pretty place to work on the boat.
__________________
Working on spending my children's inheritance.
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13-06-2015, 07:27
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#3
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Moderator and Certifiable Refitter
Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 21,526
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Re: One phase from three phase
Quote:
Originally Posted by Dockhead
Here's a question for you electrical wizards.
I am standing in a commercial port, couple weeks for free (I know the port director)......
Please advise. Also, if there is any test procedure which you recommend to be sure I've got it wired right. I guess hot to neutral to verify voltage, hot to ground to verify no voltage, right?
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Not quite right.
Neutral and ground are the same potential, ie they are connected together.
So hot to neutral should be 230V and hot to ground should be 230V and neutral to ground is 0V.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
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13-06-2015, 07:32
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#4
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Moderator

Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 35,307
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Re: One phase from three phase
Quote:
Originally Posted by Cap Erict3
If it is delta connected you will ,likely, not have a neutral.
Are you in the USA?
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Looking for another pretty place to work on the boat.
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Europe.
Sent from my SGP521 using Cruisers Sailing Forum mobile app
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
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13-06-2015, 07:33
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#5
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Moderator

Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 35,307
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Re: One phase from three phase
Quote:
Originally Posted by Wotname
Not quite right.
Neutral and ground are the same potential, ie they are connected together.
So hot to neutral should be 230V and hot to ground should be 230V and neutral to ground is 0V.
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Right, got it.
So do you agree with the principle, though? Is it true that I can take any one of the three phase pins, without regard to which one, and get 230v single phase power in the manner I propose? Or will it burn my boat down?
Sent from my SGP521 using Cruisers Sailing Forum mobile app
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
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13-06-2015, 07:35
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#6
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Registered User
Join Date: Apr 2008
Location: out cruising again, currently in Fiji
Boat: Sailboat
Posts: 1,480
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Re: One phase from three phase
Test procedure:
measure AC volts between all phases, you should read 380-400V each time. Measure from each phase to ground, you should read 220-240V each time.
A second test is to measure neutral against ground: You should read only couple volts between the two. A higher value would show a 'floating' neutral (=bad): If the neutral were on float, the 3x 220V from phase to neutral can shift, with one higher loaded phase having too low voltage and the other phases getting too high Voltage.
A good explanation of a bad, floating, neutral is here:
https://electricalnotes.wordpress.co...-distribution/
After above tests, I would connect as you describe, monitor the voltage and turn off/on your largest loads. If voltage stays stable, you should be OK.
One more thing, check the circuit breaker at the dock, it shouldn't be much larger than your shore power rating.
Dirk
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13-06-2015, 07:37
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#7
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Moderator

Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 35,307
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Re: One phase from three phase
Quote:
Originally Posted by LeaseOnLife
Test procedure:
measure AC volts between all phases, you should read 380-400V each time. Measure from each phase to ground, you should read 220-240V each time.
A second test is to measure neutral against ground: You should read only couple volts between the two. A higher value would show a 'floating' neutral (=bad): If the neutral were on float, the 3x 220V from phase to neutral can shift, with one higher loaded phase having too low voltage and the other phases getting too high Voltage.
A good explanation of a bad, floating, neutral is here:
https://electricalnotes.wordpress.co...-distribution/
After above tests, I would connect as you describe, monitor the voltage and turn off/on your largest loads. If voltage stays stable, you should be OK.
One more thing, check the circuit breaker at the dock, it shouldn't be much larger than your shore power rating.
Dirk
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Thanks!!!
Sent from my SGP521 using Cruisers Sailing Forum mobile app
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
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13-06-2015, 07:39
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#8
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Registered User
Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,452
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Re: One phase from three phase
Often, in commercial shipyards, 3 phase power is run to strategic receptacles around the yard. When a boat project begins, a portable lighting and power skid will be placed close to the work.
In US yards the receptacle will be 480 volts.
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Looking for another pretty place to work on the boat.
__________________
Working on spending my children's inheritance.
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13-06-2015, 07:56
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#9
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Registered User
Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,452
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Re: One phase from three phase
http://www.worldstandards.eu/electri...ge-by-country/
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Looking for another pretty place to work on the boat.
__________________
Working on spending my children's inheritance.
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13-06-2015, 08:50
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#10
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Registered User
Join Date: Dec 2014
Location: Lake Havasu City, AZ
Boat: Seaward 25
Posts: 295
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Re: One phase from three phase
There is "doing this" and then there is "doing this safely". Big difference! Hire an electrician or at least work with the port mechanics! You don't want to hurt yourself or someone who is diving around your boat.
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13-06-2015, 09:36
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#11
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Registered User
Join Date: Jun 2010
Location: Mediterranean
Boat: Beneteau Oceanis 50
Posts: 451
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Re: One phase from three phase
Quote:
Originally Posted by Dockhead
Here's a question for you electrical wizards.
I am standing in a commercial port, couple weeks for free (I know the port director).
This port does not take yachts or even fishing vessels, so there is no single phase power anywhere. The smallest power outlet is one of those round ones with 5 pins. I believe that it is 380/230V three phase, with one phase on each of three pins, then neutral, and ground.
So my question: Can I get single phase 230 volt power out of such an outlet by connecting any one of the three phase pins to hot, neutral to neutral, and ground to ground?
I have actually sourced an appropriate plug, so can make an adapter if I've got the electrical part right.
Please advise. Also, if there is any test procedure which you recommend to be sure I've got it wired right. I guess hot to neutral to verify voltage, hot to ground to verify no voltage, right?
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ask your mate at the port and check with their sparkies. I did it in Italy. Bought the big 3 phase male from the Marinas chandler. Got them to wire it for 240v.
Bingo it worked. If it hadn't I would have had a comeback to the Marina and chandler. Always good to have someone to blame. FYI I am clueless when it comes to 240V.
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13-06-2015, 11:18
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#12
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Moderator

Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 35,307
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Re: One phase from three phase
Quote:
Originally Posted by lordgeoff
ask your mate at the port and check with their sparkies. I did it in Italy. Bought the big 3 phase male from the Marinas chandler. Got them to wire it for 240v.
Bingo it worked. If it hadn't I would have had a comeback to the Marina and chandler. Always good to have someone to blame. FYI I am clueless when it comes to 240V.
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The port director is a sailor and is offshore and out of reach this weekend. If I can make the adapter and test it properly and if the principle is sound, I would rather not wait for him to return.
Sent from my D6633 using Cruisers Sailing Forum mobile app
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
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13-06-2015, 11:55
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#13
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Registered User
Join Date: Jan 2012
Posts: 177
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Re: One phase from three phase
There is a reason it's called hertz and it ain't ol' Heinrich... it doesn't matter if it is 50 or 60, 240V lust hertz.
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13-06-2015, 14:55
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#14
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Moderator

Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 35,307
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Re: One phase from three phase
Quote:
Originally Posted by trifan
There is a reason it's called hertz and it ain't ol' Heinrich... it doesn't matter if it is 50 or 60, 240V lust hertz.
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???
What?
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13-06-2015, 15:39
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#15
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Registered User
Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,452
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Re: One phase from three phase
Quote:
Originally Posted by Dockhead
The port director is a sailor and is offshore and out of reach this weekend. If I can make the adapter and test it properly and if the principle is sound, I would rather not wait for him to return.
Sent from my D6633 using Cruisers Sailing Forum mobile app
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When it comes to shore power it pays to get it connected by an expert.
------------------------------
Looking for another pretty place to work on the boat.
__________________
Working on spending my children's inheritance.
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