8GA to 4GA connection help

[bobkat]

I am doing the wiring on my Profish 700 Windlass with a lot of help from many people on this site especially Tuna Joe and his great pics!. I have to connect 8Ga wire which comes from the windlass to 4 GA wire that will go to the switch, breaker and then to the battery. I have found butt joint heat shrink connectors but nothing that would have 4GA on one side and 8GA on the other side. Does anyone have any ideas? Thanks for all the help.
Bob

 

[grouperjim]

Bob:

It has been awhile since I wired my Lewmar 700. If I recall correctly, I pared down the 4 gauge (peeled back and cut the excess copper strands) to fit the 8 gauge butt connector. I then heat shrinked the entire connection.

I know just enough about electricity and wiring to be dangerous.......so don't take my advice to the bank.......a subject matter expert will chime in I'm sure.

 

[DaleH]

While I have never done with that size wire, here's what I do when joining two different sizes. Say if I had a 16-AWG and wanted to connect it into a 10-AWG wire as the main run. I use the number 10 butt connector. Crimp the one side to the 10-AWG side, 10 conn to 10 wire.

Take 1" piece of 10-AWG and trim back insulator as needed. Trim back 16-AWG as needed. Cut off a 'few' of the size 10 individual strands at a time so that when you put it AND the 16-AWG into the bigger connector, you get the 'same' fit as a regular, stripped 10-awg wire does into the connector.

Use adhesive-lined heatshrink and I force 3M 5200 into ends of all critical butt connectors and ANY that goes into the bigle or may see water. Your heatshrink should be as long or longer than 3 times the length of the butt connector, IMHO.

Sometimes if the connector diameter requires you to use a 'large' heatshrink size, say like 3/8", then I may put a 1" piece of 1/4" or 5/16" HS onto EACH wire end first. These help seal the ends of the larger diameter HS over the connector to the wire size.

With the weight of those wires, make sure that run is supported so they don't bounce or chafe.

If you haven't bought the HS with adhesive in it, go to www.bestboatwirecom for best prices.

 

[DaleH]

If I recall correctly, I pared down the 4 gauge (peeled back and cut the excess copper strands) to fit the 8 gauge butt connector.

Ouch ... you just killed the ampacity rating of your 4-AWG wire ... :shock: !

 

[TopShot25]

I found a way better price on heat shrink tubing at, http://www.cabletiesandmore.com/america ... p?cPath=25

I have not purchased any yet so I can’t say what the quality is.

 

[dougmacf]

Dale, et al,

I don't want to seem like I'm hijacking this thread, but the discussion brings up some related questions in my mind. I'm also a little weak on DC theory/wiring etc. so these questions may seem obvious to you.

1. Why would you (Lewmar?) run 4 ga. from the power source, through the switch and then some (unknown) distance along in the direction of the windlass and then switch to 8 ga. in the middle of the line? Cost of running 4ga. the entire distance? Unless the power is being split up at the splice point to other devices, or runs through some type of resistor or other power drain, then isn't the 8 ga. either big enough to carry the entire load or not, in which case it should be 4 ga. all the way?

2. If the 4 ga. loses it's ampacity at the butt splice by "shaving off" some of the strands, won't it effectively be the same loss within the next 1/2 in. or so as the power runs through the splice and the 8ga.?

Believe me, I'm not trying to nit pick, it's just that, as I said, I don't fully understand DC circuits and I'm trying to learn along the way...

Slainte,

Doug

 

[bobkat]

Doug

I am far from an expert on wiring but I think I can answer your question relating to the 8GA/4GA situation. The windlass that I installed is the Lewmar Profish 700 which is popular with many Parker owners. The windlass has a red and black wire coming from the housing and running about 24 in. into the area of the anchor locker. From there to the batteries via the breaker and switch, the length of the run back and forth, dictatesthe AWG size wire that you should use. That calculated (there are calculators that figure this out) to a distance that required I used 4GA wire. I cannot run it directly to the windlass as I stated because those wires are sealed within the housing. As for the loss of ampacity etc. that occurs when trying to connect these 2 different gauge wires together, I will defer to those in the know. I will also try to get input from Lewmar during the week and post their response. A previous thread by Tuna Joe details the installation in detail with great pics. Hope this helps.

Bob

 

[Jersey Jim]

The ideal connector for different wire sizes is a "mechanical bug". It's an electrical splice that you just lay the stripped ends into and crank down with a wrench. The strands are subjected to compresion of a sliding piece of metal, and not twisting of a bolt that damages the strands. Several electrical Mfgrs. make them such as Burndy, Thomas & Betts (T&B), 3M. Any electrical supply house will have them, maybe even Lowes or Home Depot. If you want the connection waterproof, first wrap with 3m rubber splicing tape. You stretch this tape first and then wrap the joint several inches up the wire. It will soon mold/melt together on itself and will be impossible to unwrap. Be sure to tighten the connector first and even wait a while and retighten after the copper strands settle and loosen. This rubber splicing tape offers supperior dielectric properties for high voltage insulating as well (not perinent here) but also a good mechanical "cushion". Finally, wrap the rubber with your typical 3m pvc black electrical tape. I'll attach a pic if I can find one. They make these bugs from very small to very large, above and below what you are looking for. Good luck with the install.

 

[Jersey Jim]

I'll try to offer an explanation as short as possible why a short run of smaller wire is acceptable coming out of a device, but not for long runs.

First, to understand resistance and the American Wire Gauge (AWG) standard, where 10-ga. wire is sized such that 1000 feet equals 1 ohm of resistance. For each 3 gauge sizes smaller or larger, the resistance doubles or halves. Therefore, 7 gauge is .5 ohms per thousand feet, and 4 gauge is half of that (0.25 ohms per thousand feet). This doesn't sound like much resistance, and I certainly don't know how many amps a windlass draws (hopefully someday I'll need to know), but the 8-ga. wire supplied by the winch will safely handle 40 amps continually. To determine how much voltage-drop will be wasted across the wire, first understand that current is the same in the entire loop to the winch. That means if 40 amps is flowing through the breaker, there will also be 40 amps flowing through the positive, negative wires and switch. If the entire run (positive and negative) wires total 50 feet for example, then the resistance in 50' of that .25 ohm per thousand will be .0125 ohms. (50'/1000'=.05) (.05x.25 ohms per thousand=.0125 total ohms). When you multiply .0125 ohms by 40 amps, you get 0.5 volts. This means that your windlass does not receive 12 volts, but 11.5V which will operate better than voltage somewhere in the 10 volt range if 8 ga. were used. These voltage drops will be even more severe if greater than 50' is used, or if the motor draws more than the 40 amps I estimated. This is why a motor can get away with being supplied and even operated with a couple of feet of smaller wire. The voltage drop deducted from the 12 volts (wasted across the wire) is very negligible for short runs, but not 50 feet. I hope I explained this well enough without involving too much theory.

 

[bobkat]

Hi Jim

Thanks for all of you excellent information for my project. That was the last "piece of the puzzle" that I needed to complete the wiring . Before you had answered my question, I was all set to buy something that is called a high amperage post connector, pictured here. Just as a point of information, what do you think of this connector? Also, I have calculated that my run will require about 70 feet of wire.Therfore, I am looking at a voltage drop closer to 7.5V. According to both Lewmar and Parker #4AWG is fine for the 2520 model Parker. Thanks again for taking the time to answer my posts!
Bob

 

[Jersey Jim]

Bob:
I assume you meant a voltage drop of 0.75 volts, not 7.5 volts. The high amperage post displayed has three short comings that I see. First, in order for the high current to pass from one conductor to another, it must pass through 3 junctions. Two of them being "wire strands to ring terminal", and the third junction is the stacking of the two ring terminals on the post itself. Second, the connector needs a mounting surface in order to support it, unlike the mechanical bug that splices the two conductors in-line with each other. And third, albeit a mounted device and in less need of insulating, humid air can begin infiltrating the three junctions. If rubber splicing tape is applied to the bug first, or mastic sheets, the mechanical bug splice is completely waterproof, not to mention that the only junction is the strand-to-strand contact of the two wires that relies on no compression of a ring terminal crimp. I'm sure if you use the high-amperage post it will look professional, mechanically sound, and trouble free for many years. The bug however, if applied properly, will be maintenance free with no voltage drop increasing over the years as the 3 junctions begin to corrode. Either way will give years of good service.

Jim

 

[bobkat]

Jim

Yes, that was a typo 0.75V is what I meant. And I am definitely going with the bug connector and self fusing tape since as you say it will provide both no future maintenance and no further voltage drop. Thank you again. I should have the windlass completely wired this week!
Bob