Cruisers Forum
 


Join CruisersForum Today

Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 06-08-2017, 18:18   #1
Registered User

Join Date: Jul 2012
Posts: 203
Shore power fades and returns then stops

I need the collective electrical genius of the group.

On my boat today. AC is going, fridge is going and two small fans to move air. When not at the dock AC is off the rest is on. Today the fans began to slow and speed back up. Thought that was odd and the third time it happened I shut off the AC just in case. About ten minutes later the Fans began wavering and then stopped. Checked all the breakers. Nothing was thrown and nothing was warm. Check all connections back to the dock.

Popped the panel open and out with the trusty Multimeter. I have a double breaker that says 30 amps and the main power. It is a double switch linked. they both throw together. Turned all AC off and waited. Turned the master back on. When master is off it reads 120 across the lower half but not the top, Master ON no reading.

I turned Port and Starboard AC on and nothing, A couple of minutes later the fans came on for like eight minutes and died not to return.

All that to ask do breakers fade in and out as they die? I have only ever had WORK and NOT work. Breakers never popped. One more tidbit. Breakers didn't have the click feeling they should have ...just sort of move back and forth. I am guessing the breaker gave up but it is weird behavior to me.

I would have said no shore power but I have the 120v reading on the bottom half of the breaker.

Ideas?
__________________

rbrentp is offline   Reply With Quote
Old 06-08-2017, 18:20   #2
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 26,450
Shore power fades and returns then stops

Just maybe they are bad, I base that only because they way you say then feel, I'd replace any that don't snap, they could be arcing in there from a loose contact, and if they are, that is not a good thing.
Power on one side is power from the dock of course, no power on the other side when breaker is on, indicates a bad breaker, or a tripped one I believe
__________________

a64pilot is offline   Reply With Quote
Old 06-08-2017, 21:51   #3
Registered User

Join Date: Jun 2013
Location: canada
Posts: 2,607
Re: Shore power fades and returns then stops

Quote:
Originally Posted by rbrentp
Turned the master back on. When master is off it reads 120 across the lower half but not the top, Master ON no reading.


No reading where. On both sides?

If you have no reading on both sides then the issue is not the breaker. But between breaker and dock.

If you have 120v on bottom of breaker but not top When on. Breaker is bad
smac999 is offline   Reply With Quote
Old 07-08-2017, 05:36   #4
Registered User

Join Date: Jul 2012
Posts: 203
Re: Shore power fades and returns then stops

Power on bottom half not on top so ordered a breaker.

I will post when I get it installed.
Thanks
rbrentp is offline   Reply With Quote
Old 07-08-2017, 10:20   #5
Marine Service Provider

Join Date: Sep 2008
Location: Victoria B.C.
Boat: CS27
Posts: 2,042
Re: Shore power fades and returns then stops

Quote:
Originally Posted by rbrentp View Post
Power on bottom half not on top so ordered a breaker.

I will post when I get it installed.
Thanks
You have not posted enough information to determine the issue yet.

What do you mean power on bottom half? Are you referring to hot (black) or neutral (white)? Are you measuring the incoming shore power or the output side of the breaker? Are you measuring across to ground (green)?
mitiempo is offline   Reply With Quote
Old 07-08-2017, 10:55   #6
Registered User

Join Date: Jul 2012
Posts: 203
Re: Shore power fades and returns then stops

Sorry my electrical ignorance is in the way. The double pole breaker looks like two breakers adjoined. The black wire attaches to the lower half. I get no 120v reading on white wire half.
Did not check to ground (green).
rbrentp is offline   Reply With Quote
Old 07-08-2017, 11:21   #7
Marine Service Provider

Join Date: Sep 2008
Location: Victoria B.C.
Boat: CS27
Posts: 2,042
Re: Shore power fades and returns then stops

Quote:
Originally Posted by rbrentp View Post
Sorry my electrical ignorance is in the way. The double pole breaker looks like two breakers adjoined. The black wire attaches to the lower half. I get no 120v reading on white wire half.
Did not check to ground (green).
How did you measure each wire? Between black wire and which other wire?

Between white wire and which other wire?

Incoming shore power side or after the breaker?
mitiempo is offline   Reply With Quote
Old 07-08-2017, 11:51   #8
Registered User

Join Date: Jan 2017
Posts: 488
Re: Shore power fades and returns then stops

It sounded more like your shore power comes from a generator system that either became unstable or went off-line. Your breakers might not be the cause of your power failure. Could be the heat caused so much use of AC that there was a system failure. My experience with breakers is the same as yours. Breakers do not slowly decrease voltage but cause an immediate zero volts when the trip.
KP44 is offline   Reply With Quote
Old 07-08-2017, 11:54   #9
Registered User

Join Date: Jan 2017
Posts: 488
Re: Shore power fades and returns then stops

I assume you checked your shore-power plug at the ship? This sounds more like corroded contacts.
KP44 is offline   Reply With Quote
Old 07-08-2017, 12:09   #10
Registered User
 
Three Sisters's Avatar

Join Date: Feb 2016
Location: USA
Posts: 485
Re: Shore power fades and returns then stops

Quote:
Originally Posted by rbrentp View Post
Sorry my electrical ignorance is in the way. The double pole breaker looks like two breakers adjoined. The black wire attaches to the lower half. I get no 120v reading on white wire half.
Did not check to ground (green).
That breaker would commonly be called a double pole single throw.

The only other point I'd like to ad at this juncture is what you describe sounds much like a brown-out scenario, where the supply voltage drops.
This is particularly troublesome for items with capacitors where the supply voltage drops below the electrical parameters that the capacitor can withstand, and then the capacitor requires replacement. Possibly refrigeration and hvac appliances as well as many motor-driven applications to name a few. Not fun.
Three Sisters is offline   Reply With Quote
Old 07-08-2017, 12:51   #11
Registered User

Join Date: Dec 2015
Location: Nanaimo BC
Boat: modified Spray 56' oa
Posts: 358
Re: Shore power fades and returns then stops

Some dockside wiring can be downright silly. Saw a situation where to save wire only a long hot (black) ran to the ramp. The neutral white was grounded to a metal stake and common picked up again at the ramp. Actually worked until a hot dry summer when the earth dried out and caused symptoms like you describe. I was called in to trouble shoot??? Made big incantations to impress the owner and pee'd on the metal stake Ta Da.
topmast is offline   Reply With Quote
Old 07-08-2017, 13:01   #12
Registered User

Join Date: Jul 2012
Posts: 203
Re: Shore power fades and returns then stops

Other boats around me had power. I switched to a second meter and no change. For testing I put the Multimeter across the switch to see if I could get a reading. Lower unit had 120 upper did not.

A bad connector at shore power that shows 120 on MM and does not operate a small fan seemed odd to me.
rbrentp is offline   Reply With Quote
Old 07-08-2017, 13:31   #13
Registered User

Join Date: Jan 2017
Posts: 488
Re: Shore power fades and returns then stops

Quote:
Originally Posted by rbrentp View Post
Other boats around me had power. I switched to a second meter and no change. For testing I put the Multimeter across the switch to see if I could get a reading. Lower unit had 120 upper did not.

A bad connector at shore power that shows 120 on MM and does not operate a small fan seemed odd to me.
This sounds like corroded or burned contacts. The likely place to look is your shore-power cord ends and the boat's receptacle. These cord ends are the most likely culprit.
KP44 is offline   Reply With Quote
Old 07-08-2017, 19:06   #14
Registered User

Join Date: Jun 2013
Location: canada
Posts: 2,607
Re: Shore power fades and returns then stops

Quote:
Originally Posted by KP44 View Post
This sounds like corroded or burned contacts. The likely place to look is your shore-power cord ends and the boat's receptacle. These cord ends are the most likely culprit.

He has 120v across the incoming black and white on the main double pole breaker and 0v on the output side. With breaker on. It's a bad breaker

A problem upstream. You either wouldn't see 120 ever. Or you'd see 120v with breaker off. Dropping to a low number, or 0,on both sides of the breaker when turned on.
smac999 is offline   Reply With Quote
Old 07-08-2017, 19:27   #15
Registered User

Join Date: Jul 2012
Posts: 203
Re: Shore power fades and returns then stops

smac999
I do have 120 on the black wire side with breaker off testing the wires across the breaker. Breaker on and 120 goes away.
__________________

rbrentp is offline   Reply With Quote
Reply

Tags
shore power

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hot Spigot produces cold, then hot, then cold etc. rwells36 Plumbing Systems and Fixtures 15 04-01-2016 14:56
Beep then Beep then Beep Ocean Diamond 2 Engines and Propulsion Systems 23 06-11-2013 12:09
Posting Allowed, then Not, then Again ? Target9000 Forum Tech Support & Site Help 2 22-10-2011 09:51
Engine Stops - Then What? FraidNot General Sailing Forum 34 16-02-2010 14:04



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 02:31.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.