Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 22-05-2014, 04:47   #1
Registered User
 
cszosler's Avatar

Join Date: Nov 2010
Location: Australia QLD
Boat: SeaWind 850
Posts: 55
Why fuse on positive but not on negative?

Hi to you All.
If I could, I did install fuse/breaker (auto reset) on positive, but due to restricted room in water sealed junction box and resistance to bending of the cables (welding cable 0 AWG), the only option is to fuse negative side of 1500W anchor winch. For cable sizing calculation total lenght was used from battery positive to winch and back to negative, in this circuit there is no ground conection to any other reciver, it is totaly independent circuit, only including (home made) chain couter which takes mA only.
Is "fused positive" an tradition/standard or there are other factors I'm ignorant of. Gratly obligated for shearing your wisdom with me.
Chez
__________________

__________________
cszosler is offline   Reply With Quote
Old 22-05-2014, 05:21   #2
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,045
Re: Why fuse on positive but not on negative?

If you fuse the negative side, if there is a short circuit, nothing is there to protect from a fire.
You want to fuse positive and do it as close to the battery as is practicable. If nothing else get a fuseable link to put in the positive side close to the battery.
__________________

__________________
a64pilot is offline   Reply With Quote
Old 22-05-2014, 05:22   #3
Registered User
 
Reefmagnet's Avatar

Join Date: May 2008
Location: puɐןsuǝǝnb 'ʎɐʞɔɐɯ
Boat: Nantucket Island 33
Posts: 2,735
No technical reason the positive side is fused, it's more a convention.

Edit: Whoa. Two different perspectives already lol. To expand, mixing different polarity fused circuits is bad, m'kay, but the risk of fire, explosion or doom doesn't increase if the negative side is fused vs positive on a circuit.
__________________
Reefmagnet is offline   Reply With Quote
Old 22-05-2014, 05:25   #4
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: Why fuse on positive but not on negative?

The primary reason positive fusing take place, is based on a set of standard assumptions

(a) Faults paths are generally to other negative returns
(b) negative wiring is less protected then positive wiring so that contact with other returns are more likely
(c) negatives are often commoned, so that a combined fuse is useless.


Fuse positives

dave
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 22-05-2014, 06:12   #5
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Why fuse on positive but not on negative?

Quote:
Originally Posted by goboatingnow View Post
The primary reason positive fusing take place, is based on a set of standard assumptions

(a) Faults paths are generally to other negative returns
(b) negative wiring is less protected then positive wiring so that contact with other returns are more likely
(c) negatives are often commoned, so that a combined fuse is useless.


Fuse positives

dave
Bingo!!
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 22-05-2014, 06:32   #6
Registered User
 
cszosler's Avatar

Join Date: Nov 2010
Location: Australia QLD
Boat: SeaWind 850
Posts: 55
Re: Why fuse on positive but not on negative?

Quote:
Originally Posted by a64pilot View Post
If you fuse the negative side, if there is a short circuit, nothing is there to protect from a fire.
You want to fuse positive and do it as close to the battery as is practicable. If nothing else get a fuseable link to put in the positive side close to the battery.
This is it, why I did not think outside of the (sealed next to the winch) box?. Yes, I'll fuse at battery positive in battery locker, it will be moisture protected there. Thanks for opening my eyes, same as, after you open your umbrela rain drops stop. All The Best.
Chez
__________________
cszosler is offline   Reply With Quote
Old 22-05-2014, 10:38   #7
Registered User
 
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Freya 39 cutter- Terra Nova
Posts: 3,649
Re: Why fuse on positive but not on negative?

Quote:
Originally Posted by a64pilot View Post
... You want to fuse positive and do it as close to the battery as is practicable...
This is correct.
__________________

__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
Terra Nova is online now   Reply With Quote
Reply

Thread Tools
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
12v positive and 24v negative possible? heintje23 Marine Electronics 17 27-07-2013 20:11
What? No negative in panel? rhr1956 Electrical: Batteries, Generators & Solar 9 20-06-2011 11:09
I Hope This Negative Force Never Reaches My Wife ! Skabeeb General Sailing Forum 21 10-03-2011 07:12
Positive and Negative Charges Srah 1953 Electrical: Batteries, Generators & Solar 19 16-01-2011 06:42



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 10:31.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.