Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 30-07-2007, 16:32   #16
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Contrary to Lynx's suggestion, do not pare down the wire. That is very bad advice.
__________________

__________________
The Blue Dot Campaign. This Changes Everything.
DeepFrz is offline   Reply With Quote
Old 30-07-2007, 16:34   #17
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Randy, actually soldering is the "holdover" that just seems so difficult to kill.
__________________

__________________
The Blue Dot Campaign. This Changes Everything.
DeepFrz is offline   Reply With Quote
Old 30-07-2007, 16:49   #18
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 13,056
Randy-
Space and defense missiles may have rather different criteria from boat wiring. I've read USAF Rome AFB reports from the 70's that said soldering was the least reliable way to assemble components and that wire wrap was better.

Except, they didn't tell you to wire wrap those missiles, did they? And there's no wire wrap for 4AWG cables. <G>
__________________
hellosailor is offline   Reply With Quote
Old 30-07-2007, 17:44   #19
Senior Cruiser
 
Roy M's Avatar

Cruisers Forum Supporter

Join Date: Feb 2007
Location: Southwestern Yacht Club, San Diego, CA
Boat: Searunner 40 trimaran, WILDERNESS
Posts: 3,042
Images: 4
My panel receives its power via a #4 wire with crimped lugs from the battery selector switch. Power is supplied to the switch via 2/0 Anchor battery cable, via a Blue Seas class T fuse, then a separate battery isolation switch in the cockpit locker, then the battery positive terminal. The issue I was hoping to be addressed was that the current flow maximum through a short length of smaller gauge wire, connected to a much greater size cable, is still capable of tranferring the current needed between a conventional breaker and the larger cable, whose function is merely to reduce line friction losses. The issues of overcurrent, on a massive scale, is one I am familiar with, and addressed with the Class T fuse. Only Gord seems to have picked up on this. A large cable on a long run has less line resistance than a smaller gauge. Connecting a jumper cable from the large gauge seems the equivalent of a short length of smaller gauge directly to a battery terminal, leaving aside the overcurrent issues. So, have any of you ever seen or used such a jumper?
__________________
Roy M is offline   Reply With Quote
Old 30-07-2007, 18:18   #20
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 13,056
I don't read anything that indicates "and addressed with the Class T fuse. Only Gord seems to have picked up on this. " No prior mention of that Class T fuse at all that I see, did I miss it?

What I was anticipating, is that if your autopilot feed wire should short out to ground--from the 4AWG positive cable itself, by chafe or any other reason--then it could weld any conventional 30A breaker into the closed position, causing thebreaker to fail.

There was no mention of anything else to protect that line, nor any presumption of a fuse back at the battery.

If you are convinced that the battery main fuse is sufficient to protect against that scenario, and you are just using a 30A breaker to protect the autopilot, that's something else again.

The 10AWG drop from the 4AWG cable to the autopilot itself is very similar to the obsoleted "fusible link wire" that used to be common on alternators. An 18-24" long piece of wire, sized two gauges smaller than the main wiring, would be used instead of a fuse. In case of overload the fusible link wire blows (literally) and while they were jacketd with special fire-resistant insulation and sometimes sleeved as well, they've gone out of style as a fire hazard. They're still available, though. Obviously from 4AWG to 10AWG you're not quite doing the same thing--you're three sizes up.

AFAIK there are no connectors besides terminal blocks or cable lugs to fit a 4AWG cable, so a "proper" connector from 4AWG to 10AWG will either mean using a mechanical connector of some kind, or a bit of old fashioned wiring. You could literally insert and inch of the 10AWG into the 4AWG and then place a swage over them, binding them together. Or improvise any other way that gives you a solid connection. I can't see there's any problem with any robust way you connect them, as long as it is solid and keeps you happy.
__________________
hellosailor is offline   Reply With Quote
Old 30-07-2007, 19:19   #21
Registered User

Join Date: Sep 2006
Location: Keswick, ON Canada
Boat: Islander 36
Posts: 81
Quote:
Originally Posted by Roy M
I need to connect a #4 wire to a DC 30 amp breaker for my autopilot drive unit. The current drop will be less than 3% using that wire size for the twenty-something feet the duplex wire will travel from panel to the unit.
Roy,
While using the biggest conductor is a good idea .... are you sure that #4AWG tin plated wire having resitance 0.264x10-3 per 1000ft will have the voltage drop of 3% when subject to inrush current of 15A? The 15A is the "peak drive motor output" of a Raymarine S1 autopilot. Since the inrush lasts for several milisecond only I would rather calculate the voltage drop for steady state current plus 20% safety factor. For the same equipment the steady current is 6A. If you use 6A + 20% = 7.5A then the ~3% voltage drop limit (for 20ft circuit length) would be achieved for the #10AWG cable. I am talking about 0.35V loss.

Chris
__________________
Rodz is offline   Reply With Quote
Old 30-07-2007, 19:52   #22
Registered User

Join Date: Sep 2006
Location: Keswick, ON Canada
Boat: Islander 36
Posts: 81
Quote:
Originally Posted by Roy M
I need to connect a #4 wire to a DC 30 amp breaker for my autopilot drive unit. The current drop will be less than 3% using that wire size for the twenty-something feet the duplex wire will travel from panel to the unit.
Roy,
While using the biggest conductor is a good idea .... are you sure that #4AWG tin plated wire having resitance 0.264x10-3 ohm per 1000ft will have the voltage drop of 3% when subject to inrush current of 15A? The 15A is the "peak drive motor output" of a Raymarine S1 autopilot. Since the inrush lasts for several milisecond only I would rather calculate the voltage drop for steady state current plus 20% safety factor. For the same equipment the steady current is 6A. If you use 6A + 20% = 7.5A then the ~3% voltage drop limit (for 20ft circuit length) would be achieved for the #10AWG cable. I am talking about 0.35V loss.

Chris
__________________
Rodz is offline   Reply With Quote
Old 30-07-2007, 20:15   #23
Registered User
 
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Freya 39 cutter- Terra Nova
Posts: 3,652
Quote:
Originally Posted by rtbates
IF you don't know how to use a piece of heatshrink for support, yea, don't solder. If on the other hand you DO know how to use heatshrink as a wire support, then by all means solder. The 'rule' of not soldering must be a hold out and meant for the average person who really shouldn't try to use a soldering iron. I've been soldering wires at terminals, many involve systems that are subject to much greater stresses than any boat will ever see. Think SPACE and DEFENSE. One such prototype was a guidance system mounted in the nose cone of SAM missles.

I've begun to believe that when it comes to electronics and the AYBC or whoever wants to set up rules for boats and electronics, they must be stuck in the analog age.
Yo Randy,

NOWHERE on any of these missiles will you find two vastly different-sized wires soldered together because they didn't have the proper terminal on hand to do it right.

So...

I stand by my recommendation:

Do not solder.

Best is properly crimped on, correctly sized terminal for the #4 cable directly to the circuit breaker. Some cruisers perhaps will not have access to the correct terminal, but can either modify another (sized for #4), or use a terminal strip/block to secure the connection.

While it is possible to obtain an excellent soldered connection under the clean-room conditions provided by aerospace manufacturers, it is wise to use crimped connections, and follow standard practice for yachts in this case. And it will be easier for someone who later has to maintain this system in the field.

best, andy
__________________
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
Old 30-07-2007, 21:42   #24
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Don't forget that the fuse is there to protect the wiring only. It must be sized for the smallest wire in the cct.
__________________
The Blue Dot Campaign. This Changes Everything.
DeepFrz is offline   Reply With Quote
Old 31-07-2007, 10:04   #25
Senior Cruiser
 
senormechanico's Avatar

Cruisers Forum Supporter

Join Date: Aug 2003
Boat: Dragonfly 1000 trimaran
Posts: 5,832
Where's EngNate when you need him?

Steve B.
__________________
senormechanico is offline   Reply With Quote
Old 31-07-2007, 10:42   #26
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 13,056

Has this been a trick question or a test designed to weed out the landlubbers from the real seagoing electricians?

Obviously, the only valid answer is to strip back eighteen inches of the cable insulation, carefully separate the strands of wire, and then rebraid the 4AWG down to four separate neatly braided bundles of 10AWG without cutting or breaking any of the strands. All four get re-insulated with adhesive heat shrink tubing, and the three unused runs gets secured in a separate cable cover, secured per ABYC spec for future expansion.

I undestand Brian Toss and the folks at RigRite are going to be offering special splicing fids for those who haven't worked with power cables before, and can't find tinned-wire fids in their local chandlery.

__________________
hellosailor is offline   Reply With Quote
Old 31-07-2007, 11:45   #27
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,592
Images: 240
Repeating myself - the proper terminal [u]is available[/b] for the job.
Why not use it?
For instance, the Ancor #230253 (or #210253)
Ring Terminal for #4 AWG wire c/w #10 Stud Hole (breaker screw terminal).

Goto: ancorproducts.com/Products/Connectors/pdf/38.pdf
http://www.ancorproducts.com/Product...ors/pdf/38.pdf

Crimping provides a solid mechanical connection, resistant to “cold joints”, strain relief when using double crimp nylon connectors, and resistance to breaking under fatigue. Crimping, with the proper tool, is virtually fail-safe (fool proof).
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 31-07-2007, 12:44   #28
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 13,056
Gord, when Ancor says "10, 4.8mm" for the ring terminal, does that mean the entire ring--or just the hole in it--is 4.8mm wide? And what's the "10" supposed to mean, that it fits a #10 screw??

Then of course, there's the question of what kind of crimp fitting is this, that is supposed to be crimped on 4AWG without...what kind of special crimping tool?!

That's my biggest problem working with battery cables, it is awfully hard/expensive to find "proper" crimping tools. I'm thinking of just having some nice hex crimp shapes ground into a lopping shears next time around.
__________________
hellosailor is offline   Reply With Quote
Old 01-08-2007, 03:38   #29
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,592
Images: 240
Quote:
Originally Posted by hellosailor
Gord, when Ancor says "10, 4.8mm" for the ring terminal, does that mean the entire ring--or just the hole in it--is 4.8mm wide? And what's the "10" supposed to mean, that it fits a #10 screw??

Then of course, there's the question of what kind of crimp fitting is this, that is supposed to be crimped on 4AWG without...what kind of special crimping tool?!

That's my biggest problem working with battery cables, it is awfully hard/expensive to find "proper" crimping tools. I'm thinking of just having some nice hex crimp shapes ground into a lopping shears next time around.

Yes, the #10 is the breaker screw size, which requires about 4.8mm, or 0.189 inches (< 3/16") Diameter hole in the ring terminal.

Yes, it’s expensive to be properly equipped to perform high-quality professional installations. Some vendors will let you use their crimpers, if you buy the lugs (terminal) and cable from them.

Heavy Duty Lug Terminal Crimper #702040 (#8 AWG to #4/0):
http://www.ancorproducts.com/Product...ers/pdf/96.pdf

I don’t recommend the “Hammer-Vice” type tools.

Double Crimp Ratchet Tool #701030 for smaller wires (#22 - #10 AWG):
http://www.ancorproducts.com/Product...ers/pdf/99.pdf
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 01-08-2007, 03:44   #30
Provocateur & Raconteur
 
knottybuoyz's Avatar

Cruisers Forum Supporter

Join Date: Nov 2005
Location: Iroquois, Ontario
Boat: Bateau.com TW31 Modified
Posts: 3,583
Images: 87
Quote:
Originally Posted by GordMay
I don’t recommend the “Hammer-Vice” type tools.
Why?
__________________

__________________
Yours Aye! Rick
~^~^~^^~^~^~^~^~^~^~^~~^~^~~^~^~^^~~^~^
"It's not the boat "you built" until you've sworn at it, bled on it, sweated over it, cried beside it and then threatened to haul the POS outside and burn it!"
knottybuoyz is offline   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
Yanmar Starter Is Intermittent Tropic Cat Engines and Propulsion Systems 58 03-07-2014 16:54
Grounding Inverters & Chargers GordMay Electrical: Batteries, Generators & Solar 11 13-03-2011 18:50
Wire rope on a roller furling headsail. KaptainKen Deck hardware: Rigging, Sails & Hoisting 13 17-03-2007 08:44
"Ohm's Law & Boats" GordMay Construction, Maintenance & Refit 27 20-12-2006 19:59
hot wire tauras Health, Safety & Related Gear 17 02-08-2004 00:22



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 09:49.


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.