4GA cable question

Sneaks

Active member
I posted this in my build thread a few days ago, then realized that probably not everyone looks at build threads regularly (or at all), and even less would be interested in an old VW bus thread. Thinking this might be a more logical place to ask this, if it isn't, please guide me to where I should. Thanks!

This pertains to my '79 VW Bus that I'm building out, stock motor, stock 70A alternator, batteries located in factory positions on either side of the engine bay.

I have questions... my crimping supplies showed up today. I have a 150A surge\80A constant isolator kit with 4GA primary wires between the isolator and the batteries. I got a heavy lug crimper tool that can do up to 0GA so I've got that covered, but then I realized I'm not sure how I should cut the cables? Definitely not gonna get done with a pair of dikes or linesman pliers :). We carry bolt cutters on our ambulances, I could borrow one to cut it but those really are more "mash it until it succumbs" vs "cutting," awesome in a get-it-done-NOW situation but not the most elegant. Would a grinder with a cutoff wheel be just as good or should I go with the big cutters or is there something else I should consider using?

The kit says to tap into the ignition but I'm thinking the alt light wire would be a better option as it would only connect them when the alternator is putting out juice instead of combining them as soon as I turn the key? This is how the Westfalia-installed relays were wired up. Yes? No? I can jump from battery to battery if I need to in a no-start, dead main battery situation so having them combined for that purpose isn't a big need. On that, I assume since the two batteries will both be grounded to the chassis, that if I need to do that for a no-start situation, I would only need to jump positive-->positive and not both poles?

The kit has 20' of the 4GA, I'm only going to need about 5' to combine the batteries. I have a fuse panel I'm going to install under the sleep platform. I was going to use 10GA (have 100' of red and black) from the house battery to the panel, but would it make sense to use the 4GA since I have it, even if I don't anticipate much draw? I plan on connecting LED interior lighting, the 100w lights up front, a Coleman cooler, small water pump, and a few 12v outlets for small electronics to the house battery through the fuse panel. I do have a 1500w inverter that will be wired separately direct to the house battery, I've calculated that 10GA would be ok if I keep the run under 4', which I plan on mounting about 18" from the battery, so within the "safe" rating for the max 60A draw. Should I use the 4GA for that too to be safe? Thanks to anyone who replies!
 

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Sneaks

Active member
Thanks, appreciate the replies. Yes, cutting 4GA can be an issue when you are on the small side (5’2”, 118lbs) and limited hand strength (carpal tunnel), so thank you for the alternate options. Any drawback to using it as much as possible?
 
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Alloy

Well-known member
These will give a nice clean cut. //uploads.tapatalk-cdn.com/20191017/bcafb07b27fbb7125b6f6781e8312503.jpg


Sent from my iPhone using Tapatalk Pro

I have 2 pair of the above cutters but I find them to big and the bevel to be too much so they loose the edge easily.

These are what I use.

 

Sneaks

Active member
A second thanks, that explanation makes sense and answers my question.


Sent from my iPad using Tapatalk
 

DaveInDenver

Expedition Leader
Any drawback to using it as much as possible?
No performance downside to using big cable but you should watch the mechanical strain it might put on whatever you're connecting to.

For example there exists #10 ring terminals for 4 AWG cable but I'd be skeptical that just any random device or fuse block with #10 terminals can handle 4 AWG hanging from it, so watch routing and support the cable.
 

Alloy

Well-known member
Thanks, appreciate the replies. Yes, cutting 4GA can be an issue when you are on the small side (5’2”, 118lbs) and limited hand strength (carpal tunnel), so thank you for the alternate options. Any drawback to using it as much as possible?
Using it as much as possible will fill wire runs a knock outs quickly. Fore example 2- #10 (30amps) wires in a duplex cable take the same amount of space.

In addition to what DaveinDenver says...careful the weight/tension of the wire does not cause screws to back out.


No performance downside to using big cable but you should watch the mechanical strain it might put on whatever you're connecting to.

For example there exists #10 ring terminals for 4 AWG cable but I'd be skeptical that just any random device or fuse block with #10 terminals can handle 4 AWG hanging from it, so watch routing and support the cable.
I've used 4ga to #10 tinned lugs many times on runs of 40ft (20' of + & - ) at 30-40 amps onto Blue Sea 100-250A buss bars. Buss bars with #10 screws take up less space.
 

Photobug

Active member
Thanks, appreciate the replies. Yes, cutting 4GA can be an issue when you are on the small side (5’2”, 118lbs) and limited hand strength (carpal tunnel), so thank you for the alternate options. Any drawback to using it as much as possible?
The cost and effort to run a larger gauge wire is a real consideration. As you have brought up just the effort to cut the wire becomes a consideration, then crimps, support, location etc. Run the biggest wire you can to bring power to a new location then the appropriately sized/fused wire from a distribution point. It would be silly to run 4ga for some LED lights when 18 gauge might be appropriate.
 

DaveInDenver

Expedition Leader
The cost and effort to run a larger gauge wire is a real consideration. As you have brought up just the effort to cut the wire becomes a consideration, then crimps, support, location etc. Run the biggest wire you can to bring power to a new location then the appropriately sized/fused wire from a distribution point. It would be silly to run 4ga for some LED lights when 18 gauge might be appropriate.
Would just play devil's advocate and mention that if you're going to do something might as well do it right once. Inevitably you run a 12 AWG wire because all you ever think is it'll be a few lights. Then you add a fridge. Then a solar controller. Then a ham radio. Before you know it you're tearing it all out and doing it over. If you already have the cable and tools it's not going to hurt to have the overkill. The difference in cost isn't tremendous.
 

Sneaks

Active member
I won't multiquote the hell out of the responses, I do appreciate the feedback and knowledge, especially different and opposing viewpoints as it gives me both sides to consider. I hadn't considered the strain on connections (working in IT, I don't know why I didn't think...), the plan is to keep things horizontal as much as possible and keep things secured with a little slack near contact points, just to be safe. Wire run space, fortunately, isn't an issue. Will be coming up through the spare well 6" above the house battery, then under this 11"x8" sideboard.

IMG_50972.png

Would just play devil's advocate and mention that if you're going to do something might as well do it right once. Inevitably you run a 12 AWG wire because all you ever think is it'll be a few lights. Then you add a fridge. Then a solar controller. Then a ham radio. Before you know it you're tearing it all out and doing it over. If you already have the cable and tools it's not going to hurt to have the overkill. The difference in cost isn't tremendous.
This was the reason I asked, I was trying to be proactive. I've already been thinking solar, and my 2m/70cm just arrived yesterday in the mail. I've been "that PO" and done stupid\lazy\ignorant hacks when I was younger, trying to grow up a little :D. Again, thank you all for your input, I'll try really hard not to do anything stupid :D
 

Photobug

Active member
Would just play devil's advocate and mention that if you're going to do something might as well do it right once. Inevitably you run a 12 AWG wire because all you ever think is it'll be a few lights. Then you add a fridge. Then a solar controller. Then a ham radio. Before you know it you're tearing it all out and doing it over. If you already have the cable and tools it's not going to hurt to have the overkill. The difference in cost isn't tremendous.
We are on the same page on this. Notice I said pull the biggest wire you can to move power to a new location. In my case I would use larger than 4 gauge but for a jump across VW engine compartment I think 4 ga would be fine. I just see no need to oversize branch lines. As an example of my belief in overkill I am currently wiring a subpanel in my storage shed, with 125 amp subpanel, just in case.

To the OP: If you live near a harbor go check out the chandleries (marine supply stores). When I lived in San Diego I rewired a boat's electrical system using a chandlery's crimping equipment. It had nice heavy duty stuff that could cut through heavy cables and make solid crimps easily.
 

DaveInDenver

Expedition Leader
We are on the same page on this. Notice I said pull the biggest wire you can to move power to a new location. In my case I would use larger than 4 gauge but for a jump across VW engine compartment I think 4 ga would be fine. I just see no need to oversize branch lines. As an example of my belief in overkill I am currently wiring a subpanel in my storage shed, with 125 amp subpanel, just in case.
Indeed. Absolutely agree, no reason to use 4 AWG for short branch runs to the end device unnecessarily adding weight and taking up space. But it won't hurt anything if he does.
 
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shade

Well-known member
We are on the same page on this. Notice I said pull the biggest wire you can to move power to a new location. In my case I would use larger than 4 gauge but for a jump across VW engine compartment I think 4 ga would be fine. I just see no need to oversize branch lines. As an example of my belief in overkill I am currently wiring a subpanel in my storage shed, with 125 amp subpanel, just in case.

To the OP: If you live near a harbor go check out the chandleries (marine supply stores). When I lived in San Diego I rewired a boat's electrical system using a chandlery's crimping equipment. It had nice heavy duty stuff that could cut through heavy cables and make solid crimps easily.
Good idea on using a shop's tools for free. Just make sure you're borrowing an electrical crimping tool, not a swage tool made for steel cables.
 

Sneaks

Active member
I live in Maine but not near the coast. That being said, the rest of my family is up Down'east, one cousin is a lobsterman, another works at Ellis, a marine restoration company. I might have to do a visit, thanks!
 
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