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Connect two different sized wire together?

29K views 28 replies 13 participants last post by  Maine Sail 
#1 ·
Any suggestions on how to connect two different sized wire together?


We are installing an Air Breeze wind generator.


Sunny San Diego!
We have the mast up and have ordered 8 awg wires for the run to the batteries as they run is over 30'.

This conforms to the Air Breeze specs.

The wires coming from the Air Breeze look to be #10 or# 12.

I think the neutral and ground get connected together and then the natural and battery negative get run to the batter positive and battery negative.
We were thinking that putting a #10 eye solder less term end on the Air Breeze and then the same on the 3 8 awg cable. Then bolting the wires together. This does not seem ideal. They are running down an aluminum pole and will have about 8 " of slack inside the pole so they could be against the side. We could put a hose over the connections and other insulation methods but again this seems less than ideal.

Some new eyes on this and any idea welcome!

Thanks,
Chip
 
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#5 ·
Strip about 3/4 to 1" back on each wire.
Add 1" piece of self gluing heat shrink tubing to one end.
Fan the ends of both wires.
Wrap each end around the opposite wire.
Tug gently to seat.
Cover with heat shrink and heat it.


No solder necessary.

Alternatively, use heat shrinkable butt connectors sized to the larger wire, and strip double the length on the smaller wire and fold it back on itself.
Crimp.
Heat and shrink the covering to seal.
 
#6 ·
The wire sizes (AWG8 vs. AWG10 or 12) aren't all that different. One approach that might work well for you, providing a strong, solderless, water tight connection, is based on the use of good adhesive heat-shrink butt connectors plus additional adhesive heat-shrink tubing.

1. Use high quality yellow butt connectors, like the Ancor ones sold at West Marine;

2. With your wire strippers, carefully pare down the AWG8 to AWG10 size (which the yellow butt connectors are designed for);

3. Slip some appropriate sized adhesive heat shrink tubing over one wire;

4. Crimp on the butt connector using a proper crimper for heat-shrink type connectors (which don't damage the heat shrink);

5. Shrink the connector; and

6. Slip the additional heat shrink tubing over the entire connector and wire ends, and heat shrink.

This will provide a strong water tight connection.

The use of solder probably isn't a good idea as solder will likely increase the propensity of the wire to break due to wire movement. With very few exceptions, electrical connections on a boat should not be soldered. Good crimps are way better.

Bill
 
#8 ·
chip

some of these ideas to snip the 8 down in size and to make a somewhat physical connection are dangerous if you hope to pass any amount of current across that marginal connection. It will become a high resistance (hot) short and will impede the current flow.

How are you going to know that the strands you cut away on one end are still in use on the other end? You need an electrical connection that is made of a physically stout connection that is not loose, impaired or faulty by design.

buy the appropriate "bug" or "lug" dependent on the size wires or a terminal strip for that wire you want to use and do it correctly. Anything else is going to fail in short order and you will spend a lot of time,money and blame trying to find where the problem is.
 
#13 ·
Clearly, MaineSail has the best solution, provided that:

1. the OP is willing to purchase a minimum of 10 step-down butt connectors; and
2. that he has the proper crimper for AWG8 heat shrink terminals. Very few people do, and you've got to be careful not to damage the heat shrink covering.

chip
some of these ideas to snip the 8 down in size and to make a somewhat physical connection are dangerous if you hope to pass any amount of current across that marginal connection. It will become a high resistance (hot) short and will impede the current flow.

I agree it's important to make a very good connection, but I don't agree that it can't be done right.

How are you going to know that the strands you cut away on one end are still in use on the other end? You need an electrical connection that is made of a physically stout connection that is not loose, impaired or faulty by design.

This is a cute argument, but electrically inaccurate. All the strands in the bundle are pressed together under great pressure at the terminal connections. We're talking DC current here -- a maximum of 11-12 amps @ 15-16VDC -- current will flow thru the entire bundle, more or less equally. Hey....most electrical connections work like this...plugs, terminal strips, circuit breakers, etc. Only a few strands actually make physical contact with the connector, but the DC current permeates the entire bundle.
......
In the OP's case, there are other considerations, since he wants to run the wire thru a tube and, presumably, keep the splice as thin as is consistent with a good, strong connection.

The other option someone mentioned above will work, too (use larger butt connection, e.g., AWG8 and double the AWG10 wire on itself), but that would result in a larger connection and would also require a proper crimper.

I certainly agree that however it's done, DO NOT solder the cables or use wire nuts, or "twist them together".

Just for the heck of it, here are a couple of pix showing the result of the solution I originally posted (and I don't at all want to say this is better than MaineSail's solution):

Marine Antennas

Pics are at the bottom of the page...click on each pic twice for full resolution.

Bill
 
#10 ·
First off if you want it to last do it right the first time. List of materials , soldering iron or torch , solder, glue or melt type shrink wrap , ox_gaurd (never do marine wiring without it can get it at any hardware store). To answer your ? on wire sizing the larger gauge is to make sure proper current is supplied to wind gen as the wire run maybe have a drop in current due to length . Cheers and strong winds
 
#12 ·
@ MS. Why would you not solder a joint like the one described. A solder joint is surely better for current then a potentialy loose crimp and for and outside connection . I do like it when people do it that way cause its good job security for me. Lol . Cheers and strong winds
 
#14 ·
Bill

you might want to do some homework on your "facts" ....the ability of that wire (yes made of strands) to carry current is directly related to the surface area of the strands, and thereby the wire. There is a lot of science in how many strands are laid up, how they laid and in terminations so that the wire is truly 100% functional. By you removing and altering it's makeup, you have in fact reduced it's ability to carry current. Further the current travels in the "skin" of the strands, and if you remove those strands, again the capacity to carry current is diminished.

current flow in the wire is the same whether DC or AC, one only changes directions every 60 cycles, the other doesn't.

wire size DOES make a difference, and while you may say the size does not matter (see post #6)...altering the diameter (really circular mils) reduces the capacity and characteristics of the wire...in this case removing the strands of a #8, effectively reduces it to function as a #10 or #12, now with a flaw.

Having seen and repaired quite a few "poor connections" and having been an electrician for many years, and trained in both low voltage splicing as well as HV splicing I was offering the benefit of my experience.

Your solution is half baked at best, and dangerous if not well done. You and the OP are surely free to do the splice any way you want, but I guarantee that you will have problems down the line using your process or some of the "non-mechanical" solutions proposed here
 
#15 · (Edited)
Well, Dave, we're just going to have to agree to disagree.

To keep it short:

1. in a DC circuit current (electrons) flow throughout the wire, not just on the surface. This is not a radio frequency circuit.

2. AC circuits do in fact differ in that the electrons don't really flow....they influence neighboring ones.

3. Removing a few strands from the end of an AWG8 wire, and crimping it properly in a butt connector, does not render it effectively an AWG10 wire throughout its length in terms of its DC current carrying ability.

4. The issue here is voltage drop anyway, not current-carrying ability per se. AWG8 is specified because of the longish run between the panels and the batteries.

I would challenge you -- or anyone else -- to measure a perceptible voltage or current difference at the battery end of the AWG8 wire carrying an 11-12A DC load between two different setups: one connected at the other end to an AWG10 wire using butt-reducers; or one using the method I've outlined above.

Any EE's wanna pitch in?

Bill
 
#16 ·
1. in a DC circuit current (electrons) flow throughout the wire, not just on the surface. This is not a radio frequency circuit.

Bill
I do like to see credible refferences for bold statments.

a. wire manufactures show the same rating for stranded and solid wire of the same guage.
b. stranded wire is thicker for any given guage, to get thesame cross sectional area.

Higher frequencies are different, but this is DC. Even at 60hz the skin effec thickness doesn't matter for cables under 1/2-inch.
American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies
Skin effect - Wikipedia, the free encyclopedia

For practical purposes, urban legend started by folks trying to sell monster audio cables.
 
#17 ·
Your right-not too different

Ok I did not realize the wires were so close to each other. I went to Marine Exchange and looked at the wire and saw (we ordered the wire over the web) size was not that different. We bought some connectors to use and we have the good heat shrink with the glue in it. We may need to get a few more connectors a size up for doubling up some wire. We have a hydraulic crimping too we got at Harbor Freight we can use for this job. We bought it for the anchor windlass connectors and thought it was a onetime use but we still have it. We actually gave it to a family member but borrowed it back :)
Any way we have been doing so much work with battery cables I just thought this wire was heavier like a 4 awg for some reason.
We will crimp the wires and not cut any strands down. May have to double over the #10 but will see. Let you know how it goes. The reason for the larger wires is for the longer run and we do not want to defeat that.


This pic shows the connectors we got so far. There is a on\off switch we need to wire also and through a 50 AMP fuse on the battery to 8 awg wire.
 
#18 ·
You might want to check the review for that hydraulic HF crimper. The one I saw wasn't designed for electrical connections. They were selling it for that, but the dies are actually for crimping steel cables and completely the wrong size for electrical connectors.
 
#20 ·


Maine, since when does a plain oval shape die count as a proper crimp for anything?

Chip, is it at all feasible to simply remove the thinner wire from the airgen, and run the 8AWG cable all the way into it? That also eliminates the need to splice completely.

The HF tool may be the only one of its kind on the market and it sure LOOKS good, but if you find the thread discussing it...there's some question of exactly wtf they are selling and apparently even that varies from lot to lot.

Of course, folks have been known to simply use a vise and "swage" the hell out of battery lugs when there's no fancy $200 crimping tool around.
 
#21 ·


Maine, since when does a plain oval shape die count as a proper crimp for anything?
It is very commonly used on heat shrink yellow, blue & red crimps. That one will to 8GA too..

An oval heat shrink crimp die did this..:)



And this is a cut away of a crimp made by my $1200.00 AMP aerospace certified crimp tool. Looks oval to me...;)
 
#22 ·
You know, I've always wondered about those cutaways. Sure, it LOOKS like the copper strands have been smoothly and uniformly compressed. But is that from the crimp, or from the action of the saw or cutoff wheel, neatly smoothing and polishing them?

The closer we look, the more error we create?
 
#23 ·
Tested crimping tool

Ok once again I was mistaken. The wires we need to use are #6 not #8 :)

We did some testing with our Harbor Freight hydraulic crimping tool. We first bought it for one job. That was to crimp 2/0 cables from our windlass to batteries after we did a refit of the cables. We had to use the 00 dies in the tool to make that crimp. So we figured the dies would be different for the #6 cables but now we think not.


The wires #6 red\black

OK the stripping was not so great as I busted some strands but we did not have much to work with on that tool.


We tried the #6 dies in the tool and the crimp looks real good and it can not be torn apart, at least by me. We tried the #8 dies but it crimp looks too flat (right).


We used #6 cable and #6 butt connectors.


We also tried two #10 wires together into one # 6 but connector and they fit real nice. We did not do a crimp, seemed a waste of a connector.



We also tried a #10 wire bent over in two and it fit real nice in the #6 butt connector.
We will need to wire the green (ground) and white (neutral) wires together at the Air Breeze so that was one test.
We will need to wire a #10 black wire from the Air Breeze wind generator to the #6 black to battery negative so that was another test.


We also need to wire in a switch and a 5/16 battery eye to fuse terminal.
Need to purchase more # 6 terminal ends and some heat shrink with glue.
So it looks like this all works out. Now to do the job!
 
#24 · (Edited)
Tool

OK, yes I had read some reviews about the Harbor Freight tool and die sizes. It does do a nice crimp and on a 2/0 size was the only one we could really afford. As we use it rarely and it does a nice crimp it seems OK.
I do release that our anchor windlass is a critical system and checked the crimp out and it was great.
This die says 8 AWG and that would mean electrical wire would it not, or is cable sized the same?


The Air Breeze is not critical and this crimp is solid. It beats hitting it with a hammer and the tools shown do not seem to go up in size to #6.
We usually order our cables from GenuineDealz.com - Marine Electrical, Boat Wire & Cable, Custom Battery Cables and have them do the crimp. In this case we cannot have them do the crimping.

I will hate it if the anchor windlass crimp fails for some reason. We will keep an eye on it. We have a few crimps to make on our solar controller as the cables #4 need to be cut for a fuse and a fuse block.
That should be the end of the crimping we need to do. We were not planning on taking this tool cruising, 9 moths from now. May re-think that or get another one?
Whay would these crimps fail?
Thanks
Chip
 
#25 ·
Wired

OK did the Air Breeze wind generator wiring from the #6 cables to the Air Breeze #10 wires.
The need for the #6 wires is because the wire run is over 30'.
The #6 connectors worked great for this.
Now to find my darn heat gun!



Heat shrink needs to be moved into place and shrunk.


#10 to #6


Shrink the heat shrink and it is ready to mount!
Thanks for all the imput.
Chip
 
#27 ·
Note that soldering is not forbidden by ABYC, just having no other form of strain relief on a soldered connection IS.

You can solder two wires together and then form a loop in the wire, and apply cable ties.
Just to clarify..You can not do that and meet the ABYC standard.

Wire twisting, Western Union splices etc. do not count under ABYC E-11 as a "mechanical connection" to which you can then apply solder and call it a day....
 
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