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Type of cable lugs and their differences?

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DIY systems usually require some cable crimped with lugs at the end. So this should be kind of common knowledge I guess.

I see two common pure copper tinned lugs and I'm wondering what are the differences.

The first one is usually designed as SC. I.e. SC50-8 is a 50mm2 (AWG 1/0) lug with 8mm hole in it. They look like this:

1664208683184.png

The other one is the JG. I.e. JG50-8. These look like this:

1664208823450.png

There are other types too. I.e. OT50-8. Like the one below:

1664208917280.png

I'm not considering the 3rd one at all. I don't think I would be able to crimp them with the hydraulic crimper I have.

Are there any major differences between the 1st and the 2nd (SC and JG) type? The JG type is more expensive and not so common. One advantage is that it is close-ended, so it may reduce oxidation and this can be a plus for car connections where dirt and salts may get to the lug. But I'm not sure if this is an advantage for DIY solar systems.

What's your opinion on this? Are there any preferred types of lugs?
 
Unless you're using it in a mobile or harsh environment, I would think the first should be just fine.
 
The closed end variety seems pretty widely available and reasonably priced. I don't see much point in taking the risk on the open end leading to oxidation over time.
 
The neck-down barrel between wire end and terminal flat has resistance. First, make sure you don't buy cheap thin wall gauge lug. Second, the totally closed neck-down area will have a bit lower terminal resistance.
 
The JG type is not only close-ended but is called a "long lug" in the shops here. The tube in the back is definitely longer and it looks like it can be crimped in two places. The flat part is twice as thick compared to the SC type.

Compared to the SC lugs - the JG is heavier and looks a lot more massive.
 
Style 1 and 2 are both acceptable. I used ones that more closely resemble your first option but with a smaller hole.

It’s called an inspection window. One one side, it allows the installer to ensure the cable is pushed up all the way in, and also it allows an inspector to quickly visually verify as well.
Obviously an inspector would never be a case for DIY, but at minimum it’s nice from an installation standpoint.

E33F2EAA-F18D-4414-9B32-37C8BD6A0FB7.jpeg
 
I found out this and it provides some insights on the type of lugs and proper crimping.

That's a decent article.

I would argue that an inspection port is unnecessary. If you measure the interior length of the lug and cut your insulation appropriately and cram the cable into the lug, it's in there all the way and it's a good connection. Do enough crimps and you get a good feel for how much insulation to strip off. A small amount of cable showing beyond the lug isn't the end of the world since you're going to cover it with heat shrink tubing (with adhesive, of course).

Further, are you covering the inspection port with the heat shrink tubing? If not, then that's a way for moisture to get to the cable and start the corrosion process.
 
That's a decent article.

I would argue that an inspection port is unnecessary. If you measure the interior length of the lug and cut your insulation appropriately and cram the cable into the lug, it's in there all the way and it's a good connection. Do enough crimps and you get a good feel for how much insulation to strip off. A small amount of cable showing beyond the lug isn't the end of the world since you're going to cover it with heat shrink tubing (with adhesive, of course).

Further, are you covering the inspection port with the heat shrink tubing? If not, then that's a way for moisture to get to the cable and start the corrosion process.
I agree an inspection port is not needed. It’s pretty easy to tell if you’ve pushed your wire in all the way.

My favorite part of the article was that they mentioned the hole size for where you mount it to your terminal. That was another reason I chose what I chose, there were at least 4 hole sizes for a given wire lug size to choose from. So it didn’t matter if I was mounting a 1/0 cable to a 1/4” post, 3/8”, 5/16”, etc, I had the exact correct lug for the application.

And yes for me and my application, I did cover the inspection hole with adhesive lined heat shrink.

610AEEFA-749B-4566-AFC8-A8224B066758.jpeg
 
My favorite part of the article was that they mentioned the hole size for where you mount it to your terminal. That was another reason I chose what I chose, there were at least 4 hole sizes for a given wire lug size to choose from. So it didn’t matter if I was mounting a 1/0 cable to a 1/4” post, 3/8”, 5/16”, etc, I had the exact correct lug for the application.

Yeah, the coverage of the lug on the mounting surface is important. I've tried to emphasize that in posts I've made on the subject of cable lugs. The more contact that can be made between the cable lug and the terminal, the better the connection.
 
I agree an inspection port is not needed. It’s pretty easy to tell if you’ve pushed your wire in all the way.

My favorite part of the article was that they mentioned the hole size for where you mount it to your terminal. That was another reason I chose what I chose, there were at least 4 hole sizes for a given wire lug size to choose from. So it didn’t matter if I was mounting a 1/0 cable to a 1/4” post, 3/8”, 5/16”, etc, I had the exact correct lug for the application.

And yes for me and my application, I did cover the inspection hole with adhesive lined heat shrink.

View attachment 113917
This "inspection port" wouldn't fly on a marine install, it would be identified as a way for corrosion to enter the connection instead.

I'm pretty sure your inverter manual specified a molex part number for the lug. Look it up. No inspection port. At least that's what I saw on a 48V model.

I own selterm lugs in 1/4", 5/16", 3/8" (all 2AWG), and I use every size in my system. They physically look similar to the Molex part number specified by Victron and they're UL listed.

I do wish the selterm lugs fit my 2AWG flex whip Class M welding cable a little better--or maybe I'm just a little confused about why I'm needing to pump the crimper extra. My TEMco TH0818 hydraulic indent lug crimper takes about 19 pumps instead of the suggested 7 pumps to make a crimp, but they're crazy strong, and making the crimp is effortless. When I put the wire in the lug, there isn't extra room, but the ultra fine stranding seems to compress more than average wire.

EDIT: The top of that lug having been cut off flat/square... I'm guessing you're using a larger wire and lug than is recommended by the device you're connecting to.
 
That's a decent article.

I would argue that an inspection port is unnecessary. If you measure the interior length of the lug and cut your insulation appropriately and cram the cable into the lug, it's in there all the way and it's a good connection. Do enough crimps and you get a good feel for how much insulation to strip off. A small amount of cable showing beyond the lug isn't the end of the world since you're going to cover it with heat shrink tubing (with adhesive, of course).

Further, are you covering the inspection port with the heat shrink tubing? If not, then that's a way for moisture to get to the cable and start the corrosion process.

What type of adhesive and how to apply? Or is that adhesive lined tubing?

Thanks.
 
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This "inspection port" wouldn't fly on a marine install, it would be identified as a way for corrosion to enter the connection instead.

I'm pretty sure your inverter manual specified a molex part number for the lug. Look it up. No inspection port. At least that's what I saw on a 48V model.

I own selterm lugs in 1/4", 5/16", 3/8" (all 2AWG), and I use every size in my system. They physically look similar to the Molex part number specified by Victron and they're UL listed.

I do wish the selterm lugs fit my 2AWG flex whip Class M welding cable a little better--or maybe I'm just a little confused about why I'm needing to pump the crimper extra. My TEMco TH0818 hydraulic indent lug crimper takes about 19 pumps instead of the suggested 7 pumps to make a crimp, but they're crazy strong, and making the crimp is effortless. When I put the wire in the lug, there isn't extra room, but the ultra fine stranding seems to compress more than average wire.

EDIT: The top of that lug having been cut off flat/square... I'm guessing you're using a larger wire and lug than is recommended by the device you're connecting to.
good point, and makes sense in a marine usage environment. Mine is for an RV so not applicable but good note for those working in that environment.

Regarding your fitment "issue" with your 2awg lugs and your fine strand (welding) cable, I ran into similar issues with my Panduit lugs which are also UL listed, but then I realized they actually have a different lug spec'd for fine stranded hight count cables which fit better (larger I.D.) I'm not familiar with Selterm but maybe they have something as well.

For what it's worth, I don't think this is required, I could make the tighter fit options work, just took a few extra minutes per lug.

and no, it is the correct wire/lug for my application. it is not "cut off" square but is as the lug was designed. It's simply how all of there larger lugs are.

Here you go, pick a lug, any lug ;)
B6598C8F-570B-434B-96F6-B611866EFF93.jpeg
 
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A few pictures are more than hundreds of words. The JG type is made from a thicker tube compared to the cheaper SC type. SC and JG are the types you can find on Aliexpress.

No measurements yet (failing to find my caliper), but the difference is noticeable. I'll go ahead with the JG type.
 

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