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 15-12-2018, 11:43   #1
Registered User

Join Date: Mar 2017
Location: Fort Lauderdale
Boat: Gallart 13.50 MS
Posts: 30
Electrical puzzle

I've been trying to sort out the wiring on my 82 Gallart. As far as I can tell, the boat is and always has been a 110v shore power system, with probably a 30amp shore plug.

The current mystery is a small subset of the outlets around the settee. They were reading 20 volts while all the rest were reading 117 (shore power). I checked the wiring, and they seemed to be wired hot to ground rather than to neutral. Swapped that around and all seemed good, 117 on every outlet in the boat. With a stray 20 volts from neutral to ground that I needed to track down. Several candidates for that, but still working on it.

Then this morning the shore power exploded (Totally unrelated to my boat, who puts a marina junction box below the water level anyway?!?) So we unplug the shore power line, and fire up the generator. Every outlet came up fine except the settee plugs were again reading 20volts.

So now i'm confused to say the least. I don't have a split rail turning 220 into two 110 circuits. The shore power is 110 and a ground on three wires, the generator runs through an autotransformer kicking it down to 110, that goes into our autotransfer switch, then shore/generator power runs to a 3k inverter charger which outputs to the rest of the boat.

I'm seriously iffy on the inverter/charger. It seems to be reading 1 volt lower than what the battery is actually at, making it want to charge or shut off wrong. Outside of that though, it does run, it's putting out the right voltage to every other outlet on the boat. It's just being cantankerous about charging voltages. Which in no way explains to me why I have a few outlets only showing 20 volts when running on the generator.
__________________

Corvidae is offline   Reply With Quote
Old 15-12-2018, 11:51   #2
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29 49.16 N 82 25.82 W
Boat: Pearson 422
Posts: 14,220
Re: Electrical puzzle

Off the top of my head I think more information needed to do a remote diagnosis BUT like all things electrical, it's very logical. One idea, is the shore power or generator or both separated into two 110 circuits? Not necessarily 220 split into two 110 legs but running through two different switches or circuit breakers? That would be one place that things were swapped around.

Otherwise, start at one end and trace all the wires back to the other end. also, get a meter to check that all the AC outlets are wired the same way (don't depend on wire color or location) at the panel, any switches, circuit breakers or anywhere else there is a connection.
__________________

__________________
The water is always bluer on the other side of the ocean.

Sometimes it's necessary to state the obvious for the benefit of the oblivious.

Rust is the poor man's Loctite.
skipmac is offline   Reply With Quote
Old 15-12-2018, 12:03   #3
Registered User

Join Date: Mar 2017
Location: Fort Lauderdale
Boat: Gallart 13.50 MS
Posts: 30
Re: Electrical puzzle

Shore and generator power are each on a single pair of wires at 110. (Standard 30amp shore power plug) The generator does run 220, that gets broken down to two 110 circuits by the autotransformer. One of which is disconnected (verified wire is disconnected), the other runs into the transfer switch with the shore power. Regardless of shore/generator power, the transfer switch puts out 110, that then gets sent to the inverter/charger then off to the main panel.

My current suspect is that there's something wrong with a ground/neutral somewhere. I'm just at a loss as to how that turns into 20 volts.
Corvidae is offline   Reply With Quote
Old 15-12-2018, 17:07   #4
Registered User
 
mario f's Avatar

Join Date: Dec 2005
Location: caribbean
Boat: ketch, 51'
Posts: 171
Images: 8
Re: Electrical puzzle

Maybe a floating ground or neutral? in addition to miss wire. Between ground and neutral should be 0v.
As above trace wires carefully-
__________________
"It was the Law of the Sea, they said. Civilization ends at the waterline. Beyond that, we all enter the food chain, and not always right at the top.
Hunter S. Thompson
mario f is offline   Reply With Quote
Old 15-12-2018, 21:57   #5
Registered User

Join Date: Oct 2018
Posts: 133
Re: Electrical puzzle

You had neutral and ground reversed on the plug and it only measured 20 volts? I'm assuming boats are like homes and neutral is wired to ground in the main panel? If that's the case then where's the 20 volts coming from? Could the settee circuit have something in the circuit that is wired serially instead of in parallel? Or, you may have a bad connection. A voltage meter typically has an impedance in the low megohm range. Since you only measured 20 volts I would assume the resistance of the remainder of the circuit is 5-6 times the meter or around 10 megohms which may indicate a bad or corroded connection?
NPCampbell is offline   Reply With Quote
Old 15-12-2018, 22:12   #6
Marine Service Provider
 
boatpoker's Avatar

Join Date: Nov 2008
Location: Whitby, Ontario or Bahamas
Boat: Benford 38 Fantail Cruiser
Posts: 3,946
Re: Electrical puzzle

Quote:
Originally Posted by NPCampbell View Post
You had neutral and ground reversed on the plug and it only measured 20 volts? I'm assuming boats are like homes and neutral is wired to ground in the main panel? If that's the case then where's the 20 volts coming from? Could the settee circuit have something in the circuit that is wired serially instead of in parallel? Or, you may have a bad connection. A voltage meter typically has an impedance in the low megohm range. Since you only measured 20 volts I would assume the resistance of the remainder of the circuit is 5-6 times the meter or around 10 megohms which may indicate a bad or corroded connection?
No neutral and ground not joined on the boat. They are joined at generators and inverters via auto switching.

Joining neutral and ground on a boat will introduce AC into your DC wiring since your AC ground and DC negative are bonded and likely hurt someone badly.
__________________
That hysterical laughter you hear as you sail a way in your "new" boat ..... is the seller.
boatpoker is offline   Reply With Quote
Old 17-12-2018, 22:03   #7
Registered User

Join Date: Oct 2018
Posts: 133
Re: Electrical puzzle

Quote:
Originally Posted by boatpoker View Post
No neutral and ground not joined on the boat. They are joined at generators and inverters via auto switching.

Joining neutral and ground on a boat will introduce AC into your DC wiring since your AC ground and DC negative are bonded and likely hurt someone badly.
If neutral doesn't tie to ground then testing it should be pretty easy. Trip the main breaker and disconnect/switch off all power sources and devices on the settee circuit. Test for open circuits between every lead and use a 3 prong extension cord to test for <2 ohm conductivity back to the respective leads at the main panel/genset/inv.
__________________

NPCampbell is offline   Reply With Quote
Reply

Tags
cal, electric, electrical

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
Fuel Consumption Puzzle Bowman Sailor Engines and Propulsion Systems 29 29-04-2013 11:30
Complicated Electrical Question - Good Puzzle for You Electrical Geniuses Dockhead Electrical: Batteries, Generators & Solar 36 07-09-2010 07:14
Bullet 2HP Connection Puzzle bryan and wendy Marine Electronics 5 06-04-2010 12:58
Challenge: Seized Bukh - Mechanics Puzzle? Wotname Challenges 19 23-06-2009 18:50
pcs to a puzzle that works? terrydean Meets & Greets 14 27-01-2007 18:00

Advertise Here


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 04:36.


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.