Joinfworld Fused Power Distribution Block Car Audio 4 Way MIDI(Mini-ANL) Fuse Block 12V 0/4 Gauge with Ground for Auto UTV Boat Stereo Amp

What it is and who it’s for

The Joinfworld fused distribution block (model AFS‑30) is a compact, dual‑pole hub that lets you split both positive and ground in 12V systems, with built‑in MIDI/mini‑ANL fusing on the positive side. Think of it as a tidy way to run a single large feed from your battery or main breaker, branch it to up to four protected circuits, and return all grounds to a single, low‑resistance point. It’s sized for common car‑audio and powersports builds, accepts 0/2/4 AWG on the inputs and 4/6/8 AWG on the outputs (with ferrules included), and ships with six fuses (two each: 30A, 60A, 80A).

I installed it in a hatchback running a two‑amp system plus DSP and a small accessory relay. It replaced a mess of inline holders and ring terminals, and immediately cleaned up the bay and trunk wiring while making future changes much easier.

Build and design

The AFS‑30 has two mirrored sides: one positive bus with four fused outputs, and one ground bus with four unfused returns. The enclosure feels solid and appropriately dense; the terminals are beefy with large set screws, and the cover snaps on firmly. It’s not weatherproof, so while marine and UTV applications are within scope, I’d mount it in a protected location or in a sealed enclosure if spray or dust is expected.

A few design notes from my bench and install:

• The input blocks clamp down confidently on 1/0 (0 AWG) and 4 AWG. The included ferrules fit the output ports well for 4/6/8 AWG and make for clean, repeatable terminations.
• The red LED blow indicators sit across each positive fuse position. In practice, they light reliably when a fuse is removed or blown, making diagnosis quick with the cover on.
• It came with spare set screws and basic hex keys. The keys are serviceable for light snugging, but I switched to my own hardened hex drivers to avoid rounding. No torque spec is provided.

At 6.55 x 3.6 x 1.38 inches, it’s compact enough to tuck near a battery, under a seat, or on a trunk side panel. Mounting holes are easy to access with the cover off, and the footprint leaves room for gentle cable bends on 1/0 input.

Installation experience

Setup was straightforward:

1. Mounted the block on a plywood panel in the trunk using pan‑head screws and nylock nuts.
2. Ran a 1/0 positive from the battery breaker to the positive input, and a matching 1/0 ground to the chassis ground block and then to the negative input.
3. Terminated outputs using the provided ferrules on 4 AWG to each amplifier, 8 AWG to the DSP and relay.
4. Inserted fuses per branch load (80A for the sub amp, 60A for the four‑channel, 30A for the DSP and relay).
5. Verified LEDs: pulled each fuse in turn—an LED lit for each open circuit.

The clamping force on the set screws is strong and feels secure. I always prep multi‑strand cable by trimming cleanly, loading the ferrule, and using a proper crimper; you can get away without crimping ferrules if your set screw is torqued correctly, but a good crimp adds mechanical security. A small dab of dielectric grease on the copper helps long‑term corrosion resistance, especially in damp climates.

I do wish a one‑page diagram had been included for novice installers—polarity is obvious, but best practices (fuse sizing, ground layout, strain relief) aren’t spelled out. If you’re newer to 12V systems, take a minute to sketch your one‑line diagram and confirm your ampacity and fuse choices before tightening everything down.

Performance and day‑to‑day use

Electrically, it’s been uneventful in the best way. Voltage drop across the block is negligible at the currents I’m running. The single‑point ground return eliminated a faint ground loop I had with separated chassis points, and the system is quieter at idle as a result.

Thermally, after sustained listening at high volume, neither the block nor the surrounding cable exhibited concerning warmth. The mini‑ANL format is a sweet spot for car audio: easy to source, compact, and available in the 20–150A range. The included 30/60/80A assortment will get most two‑amp builds started, though serious builds may want additional ratings (e.g., 100A) on hand.

The LED indicators are more than a gimmick. Being able to glance at the block and instantly identify the circuit with a blown fuse saves time. I intentionally popped a 30A fuse with an overdrawn test load—the LED lit instantly and visibility through the cover was good.

Capacity and planning

A few practical guidelines I followed and recommend:

• Size your main input wire and upstream protection for your total continuous current, not the sum of max fuse ratings. Add headroom for transients.
• Match outputs to realistic device draw. Oversizing fuses offers no protection; undersizing causes nuisance trips.
• The input lugs accept up to 1/0 (0 AWG). If you’re working with 2/0 or larger, this block isn’t the right choice; step down near the source is not ideal.
• The ground side is a plain bus (unfused). It’s perfect for star‑grounding audio gear, but remember protection belongs on the positive branch near the source.

If you need 2/0 inputs, higher total bus current, or weatherproofing, you’ll be looking at a different class (and cost) of gear. For typical 600–1500W RMS car audio builds, the AFS‑30’s format feels right.

What I liked

• Clean, compact positive and ground distribution in one unit
• Solid set‑screw hardware with generous engagement
• Useful LED indicators for blown fuses
• Ferrules included for neat, reliable outputs
• Ships with a reasonable starter set of MIDI fuses
• Great value for bringing order to upgrades and future expansions

What could be better

• No installation guide or torque specs in the box
• Included hex keys are soft; use your own tools
• Not sealed; requires protected mounting in marine/UTV setups
• Tops out at 1/0 input; no option for 2/0 and up

None of these were show‑stoppers in my build, but they’re worth planning around.

Tips for a cleaner, safer install

• Use quality ferrules and a proper crimp tool; tug‑test each connection.
• Label each output circuit and note the fuse rating under the cover for easy service later.
• Provide strain relief—don’t rely on the set screws to carry mechanical load from heavy cable.
• Keep spare MIDI fuses in your glovebox. The included sizes cover many scenarios; consider adding 40A, 100A to your stash.
• Test LEDs by briefly removing each fuse after installation.

The bottom line

The Joinfworld fused distribution block hits a smart balance of capability, footprint, and price. It cleaned up my wiring, simplified troubleshooting, and provided a solid electrical backbone for a multi‑amp system—all without forcing me into oversized, high‑end hardware I didn’t need. It isn’t a cure‑all: there’s no weather sealing, the inputs cap at 1/0, and you won’t find pro‑grade documentation in the box. But judged on what matters—secure terminations, flexible wire sizing, clear fault indication, and tidy dual‑pole distribution—it performs like a dependable piece of kit you can build around.

Recommendation: I recommend the AFS‑30 for anyone assembling a mid‑power 12V system who wants a clean, fused hub for both positive and ground. It’s especially well‑suited to car audio, campers, and small marine or UTV electrical expansions where 1/0 main feeds and 4–8 AWG branches are typical. If your project demands 2/0 inputs, weatherproof construction, or extremely high continuous current, look at heavier‑duty blocks. Otherwise, this one offers strong value, reliable performance, and a cleaner install you’ll appreciate every time you open the panel.