Cruisers Forum
 


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 22-06-2021, 06:50   #1
Registered User
 
Tmacmi's Avatar

Join Date: Jul 2019
Location: South Haven Michigan
Boat: Spirit 28
Posts: 313
Diagnosing electrical faults

Let me start by saying this is not something I am experienced in.

The spreader lights have begun blowing their fuse after I rebuilt the fuse panel. I've gone back and checked the continuity of the switch, the fuse holder and the circuit to the lights. The all showed a strong consistent tone showing continuity.

I also measured the resistance of each of the three.

Switch 2.8 ohms
Fuse 3.1 ohms
Circuit 3.4 ohms

It would make sense that the circuit would have slightly more resistance because it is roughly a 40 foot circuit (up and back).

Here's my conjecture. There is a fray/crack in either the positive or negative loop of the circuit, however its not actually touching another line (hence no increase in resistance); its arcing under load.

Now my questions:

1) Is my conjecture accurate?
2) how do you identify if its the positive or the negative that has the fray?
3) how do you track down where the fray is?

Thank you,

Tmacmi
Tmacmi is offline   Reply With Quote
Old 22-06-2021, 07:29   #2
Registered User

Community Sponsor

Join Date: Nov 2019
Location: South Carolina
Boat: Philip Rhodes Custom 71'
Posts: 135
Re: Diagnosing electrical faults

To start with, you need a new meter.
The switch should measure zero ohms when ON and infinity when OFF.
Your meter should not be able to measure the resistance of the fuse which should be less than 0.01 ohms.
How did you measure the circuit resistance - - was the spreader light installed? The light should have an order of magnitude more resistance than the wiring.
__________________
Ann-Marie Foster
YANDINA is offline   Reply With Quote
Old 22-06-2021, 07:36   #3
JBP
Registered User
 
JBP's Avatar

Join Date: Sep 2016
Location: PA
Boat: Jeanneau Tonic 23
Posts: 73
Re: Diagnosing electrical faults

For spreader lights it's possible that the frayed wire is intermittently shorting in the mast. Your comment "after I rebuilt the fuse panel" suggests maybe not. Difficult to diagnose reliably diagnose. Yandina is correct in that the switch and fuse should either be 0 Ohms or infinity, but if you are testing them in circuit, you are probably measuring the circuit, not the switch/fuse.
JBP is offline   Reply With Quote
Old 22-06-2021, 07:40   #4
Registered User
 
Tmacmi's Avatar

Join Date: Jul 2019
Location: South Haven Michigan
Boat: Spirit 28
Posts: 313
Re: Diagnosing electrical faults

The the meter is fine. Its the operator that is the problem. I need to learn how to use the bloody thing.
Tmacmi is offline   Reply With Quote
Old 22-06-2021, 08:07   #5
Registered User
 
Cheechako's Avatar

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 23,918
Re: Diagnosing electrical faults

Most lengths of wire will show resistance. Not a lot though. Maybe a 1/4 ohm in 100 ft.
I would be checking the fixtures and wires passing through the spreaders up the mast. Also for corrosion.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 22-06-2021, 08:36   #6
Registered User
 
Dsanduril's Avatar

Join Date: Aug 2011
Location: Petersburg, AK
Boat: Outremer 50S
Posts: 4,024
Re: Diagnosing electrical faults

Disconnect and isolate the negative wire from the spreader light at the panel. Then measure the resistance between the positive wire and your battery negative/negative bus bar. If you don't have infinite/very high resistance then you have a short somewhere.
Dsanduril 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
Beneteau Oceanis Electrical Panel - Faults? RJV Marine Electronics 25 07-03-2018 01:39
Site Faults Experienced OldPierre Forum Tech Support & Site Help 1 14-10-2014 04:20
Diagnosing battery/charger/starter issue? robillard Electrical: Batteries, Generators & Solar 11 03-03-2013 15:20
Do Solenoids Go Bad ? Need Help Diagnosing This ... crewofnoka Construction, Maintenance & Refit 11 03-07-2011 04:21
Preventing Ground Faults on Boats GordMay Electrical: Batteries, Generators & Solar 4 19-09-2007 21:30

Advertise Here


All times are GMT -7. The time now is 02:45.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.