I'm a quality/compliance manager at an industrial automation distributor. I review every BOM and panel drawing before it reaches customers—roughly 250 per year. In 2025, I've rejected about 3.5% of first submissions. The usual cause? A Weidmuller fused terminal block with the wrong fuse, a power supply that's undersized, or a network jack that nobody specified.
This checklist is for engineers, panel builders, and maintenance techs who need to put together a small control panel or add circuit protection. It's not a full design guide. It's the list I use when I'm checking someone else's work.
What Is Networks in an Industrial Panel?
If you're new to this, networks in an industrial panel are the data paths between control devices. In practice, they're copper or fiber connections, Ethernet switches, industrial jacks, and the cable runs between them. The phrase makes it sound abstract; it isn't. It's an RJ45 jack on a DIN-rail switch and a shielded cable from the PLC to remote I/O.
One further note on the word jack: people use it loosely. A jack is the socket, not the connector on the end of the cable. In a BOM, write down the exact jack and the mating plug. Otherwise, you get a carton of parts that don't fit.
There are also two types of networks in a typical machine: control networks like PROFINET or EtherNet/IP, and safety networks like Safety over EtherCAT. Both end at a jack. If you don't know which one you're building, the hardware selection changes completely.
The 6-Point Checklist
1. Confirm the Weidmuller Fused Terminal Block Family
The Weidmuller fused terminal block you'll see most often in 24V DC panels is the Weidmuller ZDK 2.5. According to Weidmuller's catalog as of January 2025, the ZDK 2.5 is a screw-connection fuse terminal block for 2.5 mm² wire, with a 5 × 20 mm fuse and published ratings around 250 V / 6.3 A. But check your exact part number—Weidmuller makes versions with and without indicator lights, and with different fuse links.
- Confirm the wire cross-section: 2.5 mm² is standard, but don't assume.
- Confirm the fuse size: 5 × 20 mm is common, but some variants use 5 × 25 mm.
- Confirm the voltage rating: 250 V is typical, but your application may need a higher rating.
2. Size the Fuse, Not Just the Wire
The most frustrating part of reviewing BOMs is finding a 'fuse terminal block' with no fuse rating on the BOM. You'd think the fuse rating would be obvious, but it's the first thing that goes missing. Pick the fuse based on the circuit's continuous load, not on what the wire can carry. For most control circuits, I use a fuse rated at 125% of the continuous load—check your local code—then verify it against the inrush of solenoids, contactors, or DC-DC converters.
For example, a small 24V DC relay coil might draw 0.1A and can use a 0.5A fuse. A solenoid valve can draw 1.5A inrush; it might need a 2A slow-blow. The ZDK 2.5 accepts standard 5 × 20 mm fuses, so you have room to match the fuse to the load.
3. Choose the Power Supply Before You Finalize the Fuse
Now look upstream. The supply has to feed all your fused branch circuits without tripping on inrush. If you're building a small panel with a PLC, a few sensors, and one Ethernet switch, the Platinum BP5450 from Weidmuller is a common pick. It's a 24V DC power supply rated around 5A, and the version I've specified has a DC-OK relay contact. That relay is worth paying for: it lets the PLC tell an operator 'the 24V rail is down' instead of leaving them guessing.
Before you commit, add up every load on the rail—including the network switch and external sensors. Then add 20% headroom. The BP5450 is fine for a small machine, but it won't save you if the actual load is 8A. Check Weidmuller's datasheet for your exact variant, because there are different terminal versions and input ranges.
4. Specify the Network Jack and Switch at the Same Time
Back to the question from the top: what is networks in a panel? It's an infrastructure decision, and it ends at a jack. For a DIN-rail cabinet, choose an industrial Ethernet switch and the matching RJ45 jacks before you route cable. Weidmuller has DIN-rail switches with RJ45 jacks and rugged connectors for field cables. If you're only connecting a PLC and HMI, an unmanaged switch might be enough. If you're running PROFINET or EtherNet/IP with multiple devices, go managed.
Check the jack's protection class. Inside a cabinet, an IP20 RJ45 jack is fine. For a washdown area or outdoor machine, you'll want IP67 connectors. And don't forget shielded cable—industrial networks typically need shielded RJ45 jacks to maintain signal integrity.
5. Verify the BOM Against the Actual Hardware
I've rejected BOMs where the line item says 'Weidmuller fused terminal block' but doesn't include the order code. There are dozens of terminal blocks in the ZDK family alone. Write down the exact part number. The same goes for the power supply and the jack. If you're buying through a distributor, give them the full Weidmuller part number, not just 'ZDK 2.5.'
And if you're worried that a small order will get ignored: don't be. I've ordered ten ZDK 2.5 blocks and one Platinum BP5450 for a prototype, and the distributor treated it like any other order. Small doesn't mean unimportant—it means potential.
6. Label the Fuse and the Supply
This sounds boring, but it saves time on the first service call. Use a thermal label printer or a permanent marker to note the fuse type, the fuse rating, and the supply voltage on the inside of the panel door. I've seen smoke from a mislabeled fuse more than once—note to self: always check labels before applying power.
Common Mistakes I Check For
- Writing 'fuse terminal block' on the BOM without a part number. If you don't know whether it's a ZDK 2.5 or a different family, the buyer doesn't either.
- Assuming a fuse terminal block includes the fuse. It often doesn't. Add a 5 × 20 mm fuse as a separate line item.
- Forgetting the jack. A panel with a managed switch and no specified RJ45 jack is a panel that stops at the switch.
- Choosing a power supply with enough watts but no DC-OK signal. The Platinum BP5450 has it; some budget supplies don't.
Two caveats. First, my experience is based on roughly 250 BOM reviews, mostly in food, beverage, and packaging machines. If you're in a sector with stricter approvals—marine, oil and gas, or medical—your standards are different. Second, this approach worked for me in 24V DC control panels with predictable loads. If you're protecting AC motor circuits or dealing with high-inrush loads, the ZDK 2.5 might not be the right family at all.
Don't hold me to the exact specs in this post. Use Weidmuller's published datasheets for your exact part numbers before you order. That's the checklist.
