Quick electrical questions

[JeffM]

After 3 seasons with a little detachable combination dingy light, I got me shiny new 6-LED side lights from Duckworks.  Duckworks has a nice article on aligning them, but now to hook them up...  Um, I figured to hook them directly to one of my deep cycle batteries, simply disconnecting them when I want them off.  Am I right in thinking I need nothing else-- no fuse, etc?  Also, how do I connect stranded wire (which the lights have) to solid copper wire?

[JeffM]

Uh...yeah, Ray: just yankin' your chain.  By the by, these lights draw maybe a quarter amp total, so what should I look for in a fuse?  I don't expect to use DC for much else on the boat.  and thanks!

[Ken_Potts]

Jeff - Are the lights rated for the voltage of the battery?  I know the answer is yes, the only reason I ask is because my LED lights from Duckworks run on 3 volts (and LEDs typically run on low voltage).

Ray - Why are soldered connections bad on boats?  Is it a mechanical failure (vibration) thing?  If so, it seems like there would be no more of a problem with a soldered connection than a mechanical connection at a terminal block...

[Ken_Potts]

With the proper splice the wire won't be loose and with the proper fuse that wire won't get hot  ;D

I understand the mechanical stress of making the stranded wire into a solid wire with solder, though.  I can see why a terminal block might be favorable from a fatigue point of view.

Isn't engineering fun stuff?  

[PAR]

The reasons solder isn't used with general device connections on boats, are corrosion and fatigue resistance. ABYC doesn't ban solder. It just can't be used as the support on that end of the wire. This seems logical, but is all too common.

Look at the back of an instrument panel and you'll see lots of attachments, with very few "strain relief" arrangements employed. If these are soldered connections, they'll fatigue and break. This is quite common on powerboats where vibrations can be high.

ISO 10133 doesn't mention solder and AYBC 11.16.3.7. makes their recommendations fairly clear.

Battery connections typically are soldered for example, with the recommendation being solder commuting 1.5% of the diameter, into the strands.

[Ken_Potts]

I'll just have to make sure that my electrical connections aren't critical to the safety of the vessel.  If the wire for the blender breaks I'll have to drink it "shaken, not stirred"

Yes, I'm talking about a battery that is too small to burn the boat down (mostly I'm just kidding).

[Bikermouse]

I'll just have to make sure that my electrical connections aren't critical to the safety of the vessel.  If the wire for the blender breaks I'll have to drink it "shaken, not stirred"

Yes, I'm talking about a battery that is too small to burn the boat down (mostly I'm just kidding).

I've seen 6-8" flames shooting up from a shorted starter circuit on a motorcycle.  It was a YTX4-BS, which is a 4 AH battery.  You sure yours is too small to start a fire?

[Ken_Potts]

You sure yours is too small to start a fire?

Yep - The blender was just a joke.  I have a zero amp-hour battery on my boat...

[PAR]

I don't solder Ray, having replaced too many 50's and 60's era electrical systems with soldered connections. You'll find most europen builders do solder, but use untinned wire (why?), where as in this country we crimp and use tinned wire. Europen systems seem better designed and have good strain relief everywhere (for the most part) American manufactures have limited strain relief and systems that seem designed by monkeys with some electrical training. The only time I've found this not to be the case is on vendor installed equipment, which typically exceeds the manufacture's quality and standards. Of course custom builder don't usually suffer from this.

[Greg Luckett]

I work for Whirlpool in its Tech Center doing product development and testing.  Bad crimps account for a large percentage of "rapid oxidation" events therefore we test for this extensively.  ABYC does not like solder because it will crack/break under mechanical stress, but then so will crimps, and many hand crimping jobs are very poor quality.  This is why I do not think much of the ABYC thinking on this subject.  As mentioned by PAR, strain relief is the real key.  Check out the NEC or CSA codes.  Those Canadians and European codes are far more stringent on strain relieving. If I make a connection using solder, I can be very sure it is not going to develop a high temperature due to a poor connection.  No connector of any kind carrying current should be installed with strain on the connection via its wiring or otherwise, or eventually it will fail as a result, overheat, and lead to damage.

[Greg Luckett]

Did I mention I also do lightening strike simulations on appliances too.  That can get really exciting. ;D

They won't let me add gasoline to anything yet, but I keep hoping. ;D

[Greg Luckett]

Yep, you are right Ray....in an ideal world.  Crimps in appliances are made the same way, with similar specifications, or via automated crimping machines.  It is the reality that bad crimps are more common and worse than soldered connections.  Strain relief is the key.

[Tom Lathrop]

Crimping seems to be the most recommended method of making connections on boat wire.  As some have pointed out, the main argument against soldering connections is vibration caused by poor strain relief.  Maybe the thrust should be to promote proper strain relief, which is not well understood by many amateurs.  I would consider poor crimps to be as bad as poor soldering on a boat.  Who has a really good (and expensive) crimping tool for all the different connections needed on a typical boat?  Crimps also need tinned wire and tinned connectors to meet their potential (pun intended) in the marine environment.

Good strain relief can be had by placing a section of heat shrink tubing over and a bit beyond the connection, bending the wire in an arc to insure that no tension can be placed on the connection and anchoring the wire a few inches from the connection with some kind of tie down.

Ray is correct that the main fuse is to protect the wire and not the fixture on the far end.  However, if the wire is properly sized for its use, a fuse to protect the equipment will automatically be well on the safe side for the wire.  Otherwise there will be way too much voltage drop in the feed wire.

Solid wire has no place on a boat.  Tinned wire is preferred but most boats out there are wired with untinned wire.  The sheath on ABYC tinned wire is also much better than any ordinary plastic covered wire.  Any connection should be avoided like the plague in the bilge of a boat.  If it can't be avoided,  then it should be soldered, covered with a sealant and encased with heat shrink.  A good crimp should be ok here, but I like a good solder joint.  Been doing this for 60 years and have my own ideas.  

 

[lbrewer]

I think electrical systems are one of my weakest areas in boatbuilding (and other endeavors).  I am following this with much interest.  There seems to be agreement with everyone that strain relief is a really major issue.  I understand why, but I probably haven't paid enough attention to it in the past.  I don't think I've ever seen, much less used, a ratcheting crimp like Ray referred to.  I do know that I have never been satisfied with electrical connections I've made with crimps, terminals and crimping tools that I've bought at auto parts stores.  I hope this thread continues to expand.  I've plenty of room to learn on this one.

Larry

[Greg Luckett]

About the only thing an auto store crimper is good for is a hammer,  and it sucks at that too.

A proper crimper is not all that big an expense.  Well under $50.00.  The cheap ones are not worth buying at all.

I could not agree more.  I use either the Ideal or the Kline....maybe the same company now...for 10 gauge or smaller, but the ratcheting ones for anything 10g or bigger.  That is the one that cost the bucks for a decent one that works well. I usually just borrow one from work.  The last time I priced one of those, about two years ago, its cost was in the $150 to $200 range, but I do not recall the details.

[Tom Lathrop]

Klein tools are fine but there are others.  You can make perfectly acceptable crimp connections with the cheap tool on the right side too.  I think $100 to $200 is way to much for a little used hand tool like this.  Th Klein at $23 is certainly worthwhile for most of us.

[Greg Luckett]

Klein tools are fine but there are others.  You can make perfectly acceptable crimp connections with the cheap tool on the right side too.  I think $100 to $200 is way to much for a little used hand tool like this.  Th Klein at $23 is certainly worthwhile for most of us.

I agree with you about the costs versus usage. I have two of the Kleins, and an Ideal brand which I like a bit better as it is slightly wider and makes a better crimp. If you use that cheap one, and it is thinner, it will pinch the stranded wire, reducing its mechanical strength and also is more likely to create a high current area, ergo a hot spot.  Based on my own experiences in the testing labs, I would be worried about any crimp made with one, especially if it is a high current draw circuit.  That would be anything above about 5 amps at 12VDC.

Incidently, has anyone besides me been using MTW wire on boats?  Specification wise it meets or exceeds the marine grade stuff and cost less and is easier to find.  What do you think Ray?

[Greg Luckett]

What is MTW wire?  Never heard of it.

Machine Tool Wire. Some links to explore:

http://www.alanwire.com/awscripts/makspecs.cgi?ntype=MTW

http://www.wiringproducts.com/contents/en-us/d261.html

http://www.mikeholt.com/forum/Forum1/HTML/004436.html

[JeffM]

Cool, Greg!  Now I'm thinking of throwing my light cord from the box store into a drawer and ordering a spool of MTW to go with the Duckworks fuse panel I'm gonna get.  I confess the rest of the discussion seems a bit esoteric for my little application.

[Tom Lathrop]

OK Jeff,  But do yourself a favor and fuse between the battery and the panel.  Many people neglect this figuring the panel si fused.

You really want to protect the wire to the panel too.

And that is where you would like one with an AIC rating consistent with the battery size you are using.

Ray,

That is good advice but I think that some may not understand what you mean by "protecting the wire".  What I would mean by that statement is that, should a short occur in the wire, the primary fuse will blow before the wire heats to the point that a fire might result.  A fuse at the far end, like in the main panel, will not serve that purpose.

At the low voltages available from boat batteries, the wire is generally sized based on voltage drop and not it's capacity, as it might be at the higher voltage in a home.  If you make the primary fuse about double the maximum draw expected with all equipment on that circuit operational, you should be safe from wire short troubles and not blow the primary fuse from end equipment problems.