Electronic Component Procurement Guide – How to Source Every Part

Any sourcing job has a few general criteria to watch for, regardless of component type. Some of them are obvious, others not so much:

• Quality 
• Availability 
• Application fit 
• Standards and regulations 
• Warranty and support 
• Cost 

Quality

This is the one your engineering team will care most about. Bad actors can cause:

• Circuit failure
• Poor performance of assembly
• Damage to equipment
• Danger to humans

Part quality problems most often come from:

• Bad batches: Variations in the manufacturing process can lead to inconsistencies across production runs. A poor-quality batch could result in circuit instability or shoddy performance.

• Counterfeits: The internet is a sea of low-cost fake parts that often compromise on quality. Accidentally ordering these imposters can lead to circuit failures and safety hazards.

• Obsolescence: Discontinued parts don't magically disappear the moment the manufacturer ends last-time buys. Using outdated components still on the market can render your design obsolete, affecting the performance and useful life of your product.

Availability

The waiting game isn’t fun, and it’s easy to lose.

Make sure the electronic components you’ve honed in on are available in the necessary quantities. Sometimes small-order lead times are short. Don't assume you'll get the same speed when you make a bigger order, even if it's the same part and manufacturer.

Order early and often if the parts are:

• Obscure
• In-demand
• Heading toward obsolescence

This approach makes replacements and expansions straightforward, limiting downtime and costly redesigns.

Another, more design-focused approach to shortages is substituting in an alternative part that offers similar functionality. You certainly shouldn’t throw safety or quality out the window, but settling for “close enough” might get your project out the door months sooner.

Tip: If your components tend to play hard-to-get, enlist the services of a distributor. Unlike a single buyer, a distributor has an extensive supplier network and a constant finger on the pulse of market changes.

Application Fit

If you’re building equipment whose failure could cause the loss of human lives or million-dollar machinery, don’t instinctively buy the cheapest wire or circuit protector.

When picking components, think about where and how your team will use them. For example, the intense heat of industrial furnaces or the freezing conditions in transportation refrigeration call for parts that can thrive in the extreme. In an energy facility with nonstop vibration, the components need to be mechanically tough. 

It’s also important that any new components play nicely with your current system. Talking to product experts or using simulation tools to see how your choices might hold up can save you headaches and money later.

To sum it up: Match your investment to the level of electrical performance, flexibility, and size you need. The results will be more durability and less upkeep – for both the part and the assembly. 

Standards & Regulations

The importance of certifications and standards largely depends on your use case and industry. Chances are you already have some marching orders for compliance – we’re talking about electricity, after all.

Electronic component standards usually account for:

• Safety
• Reliability
• Durability

If your company isn’t comfortable with selecting compliant parts, talk to an experienced distributor. If you can’t trust the component to do its job, how can you trust the full assembly to do its job?

Warranty & Support

This concept isn’t much different from a commercial electronic product like an iPhone. A warranty should reflect the maker's confidence in its product's durability and performance.

An electronic component purchase with a good warranty offers more peace of mind than a bad warranty or none at all. When sourcing electronic parts, weigh the importance of the component vs. the manufacturer’s warranty:

• Length – Reduces risk of incurring additional costs for replacements or repairs
• Coverage – Some warranties may cover only parts, while others include labor and even replacement services
• Terms – May include limitations on usage, environment, or maintenance requirements

Don’t forget your needs after the parts arrive. If your own operation lacks experience with the type of parts you need, check out the maker’s level of tech support. In big projects, after-sale services can soften the integration’s impact on your schedule. Give bonus points to sellers with full training resources and a maintenance program.

Cost

We were sneaky and waited until the end to include this.

Why? Because you already know upper management wants you to find cost-efficient parts.

Actually, there’s another reason: Too often, procurement specialists go for the cheapest component possible. This short-sighted strategy may introduce into your design:

• Counterfeit parts
• Low-quality parts
• Parts that aren’t the best fit for your application

All of these mistakes can result in having to reorder parts, rework designs, and redo the production stage. These “re-”s in turn lead to:

• Downtime
• Delayed launch
• Extra testing
• Poor reputation with customers

If that happens, guess what your short-term “savings” got you? More long-term cost.

Thinking long-term means accounting for all factors of purchase cost:

Most major manufacturers’ products come with a hefty price tag. You’ll have to decide whether the quality is worth the cost – for today and 5 years from now.

Overview of Cable & Wire Sourcing

While intricate layouts and fancy technology can make a product design sing, industrial cables and wires are just as crucial to performance, safety, and durability. 

With an absurd amount of variety available, it can be overwhelming to browse a manufacturer’s e-store.

Several factors contribute to the durability of a wire assembly, including its diameter and protective coatings. Today’s customers are demanding smaller and smaller designs, which makes the physical side of cable performance more challenging to manage.

Will your cables be at risk of being stepped on, run over, or cut? Two traits to watch out for are crush and cut-through resistance.

• Crush resistance – Use jacketing/insulation made of polyethylene, Neoprene, nylon, or thermoplastic rubber. Stick to steel conductors, fillers, & armoring.
• Cut-through resistance – Use jacketing/insulation made of nylon, TPE, fluoropolymers, or XLPE. Try nickel-plated conductors, polyimide tape fillers, & steel armoring.

Gauge matters to electrical performance, as thicker cables generally have lower resistance and can handle higher electrical loads across long distances. Select a gauge that can safely carry the current your application requires without overheating or losing voltage. 

Length is important too, but for more than just physical spacing of its connection points. A cable’s signal decreases as it travels, making excessively long cables a poor fit for applications that need low losses.

At the same time, your project may call for a cable with some mechanical flexibility. This means the product is usable in tight spaces without snapping due to bending stress.

Types of Industrial Cable & Wires

Given the complex needs of industrial assemblies, the vendor often has to correct the purchaser on the best cable type for their application. Even project engineers who don’t specialize in wiring can benefit from expert recommendations.

Once you know which industrial cable type you need, the next step is matching your application to a specific material and product. Some categories of cables serve dedicated purposes.

Power cables connect electrical equipment and machinery to power sources. Control cables transmit signals between devices and automated systems. Communication cables transmit data and signals throughout networks, connecting computers, PLCs, and other devices. And instrumentation cables send data recorded by sensors and measuring instruments.

Overview of Cable & Wire Labels

Industrial marks and labels might be small, but they can have a huge impact on your application. An effective and consistent labeling and signage system can make your operation:

• More productive
• More profitable
• Less of a hassle
• Safer & more secure

Those benefits are easy enough to understand, yet the seemingly endless types of labeling solutions can overwhelm a sourcer at first glance. While all wire marking solutions have the same universal benefits, each type best meets a certain range of applications. Selecting the best wire and cable labels comes down to safety, compliance, termination location, and material needs.

Types of Industrial Cable & Wire Labels

While there are many wire identification options out there, industrial electrical cable and wire markers fit into three main types:

Heat-shrink sleeve labels slip over the cable before termination. They allow users to slide them along wires or cables for optimal placement. Once you apply heat to affix the label, you’re stuck with that location. 

The heating process shrinks the sleeve to a predetermined size, typically 1/3 to 1/6 of its original diameter. For industrial labeling needs, it's crucial to select the appropriate diameter and type of sleeve. You can cut the length to size prior to heating.

Wrap-around labels are for use after termination. These labels are adhesive and wrap around the entire diameter of a wire. Available in preprinted and stand-alone forms, the material is typically clear polyester or vinyl, with a small, white area for marking by hand or printer. Special types of wrap-arounds are available for adding moisture protection, repurposability, or readability.

Flags can go on cables before termination to help ID them during installation, or after termination to provide permanent labeling. The material partially wraps around the cable and sticks to itself, forming a flag-like extension. This design is particularly useful for identifying cables in dense or hard-to-reach areas.

Tags also work either before or after the cable’s termination. The material makeup can be either plastic or metal. Tags’ main difference from cable flags is that you have to attach them with a tie or similar fastener. On the plus side, this makes them more durable for permanent labeling situations.

Overview of Fuses

Industrial fuses come in so many easy-to-find types that it’s common for two to look nearly identical. Problem is, they might function just differently enough to be dangerous. Worst-case scenario, this guessing game can lead to selecting the wrong fuse, putting people and expensive equipment at risk.

At least voltage rating is easy enough to nail down – all fuses are straight voltage-rated. A straight voltage rating means you can use the fuse in circuits with a nominal voltage up to its rated value between any two conductors. For example, an industrial fuse with a rating of 250 V is OK to use in a circuit where the line-to-neutral or line-to-line voltage is 250 V or less.

Overall, some buyers feel that fuses are simpler or more consistent sourcing options compared to mechanical overcurrent devices. If you’re not sure, ask a distributor with technical product expertise.

Interestingly, sizing an industrial fuse means taking both electrical and physical needs into account. The fuse’s voltage rating must comfortably exceed your application’s current level, or else it’ll blow needlessly. However, it must also fit inside the assembly without crowding other components, which could lead to heat buildup and other performance issues.

Start by calculating the maximum and minimum fuse ratings:

• Wattage / voltage = max fuse rating (amps)
• Max fuse rating * 1.25 = minimum fuse rating

Don’t use any so-called “10% rule.” Size the fuse for safety first, and keep the value well above the expected load. Balance this against the internal dimensions of the fuse’s intended home. Spec a fuse to a plausible maximum load to avoid overspending.

Finally, don’t forget to watch for these other factors when sourcing fuses:

• Current rating should be slightly above the circuit's normal current, but below the wire’s or device’s current capacity.
• Interrupt (breaking) capacity will need to be high if you’re working with a high-voltage application.
• A current-limiting fuse reduces the duration and magnitude of a fault current, minimizing equipment damage and protecting people.
• Corrosive & environmental threats are avoidable by picking a fuse with the right temperature rating, coating, fire rating, or build for your application.
• Speed comes in four tiers – ultra-rapid, fast-acting, time-delay, and dual-element – and should be selected based on how quickly you need circuit interruption.

Types of Fuses

Most buyers categorize fuses one of three ways: build, application, or operating characteristics. While it's tempting to go for the cheapest option in a given category, remember that a fuse is a safety device.

No matter the type of fuse, you’re buying it for one-time use. Once it does its job – stopping a current from harming the circuit – you’ll have to replace it.

Overview of Relays

Industrial relays are versatile electronic components that are just as handy for simple circuits as they are complex ones. If you use them in place of switches or high-amp wiring (when appropriate), you can save money and assembly space.

As is often the case, both electrical and physical traits matter when selecting a relay. Understanding a few basics will set you off on the right path.

• Mounting type will impact the space available in the installation, and how much heat buildup the relay will contribute.
  
  
• Switching type can be either normally open (NO), normally closed (NC), or changeover (CO). This impacts the relay’s speed, ability to handle current, durability, and more.
  
  
• Surge current durability refers to input surge current (or inrush current), the maximum amperage a relay contact can withstand for a specific load type. To keep your system safe and reliable, compare any potential relay’s maximum surge current rating with the application’s expected inrush current. Leave a little margin for error, just in case.
  
  
• Voltage rating is different on a relay’s contact side vs. its coil side. This is because the relay needs to switch and handle the load current, which may have a different voltage requirement than the control circuit. Most industrial-grade relays come in 24-, 48-, 120-, and 240-volt options.
  
  
• Operating environment factors that most affect relay performance include hot, cold, humidity, corrosives, and vibration. Specifically, trouble areas include manufacturing, oil, gas, and mineral applications.

• Isolation between control & load circuit helps protect sensitive control circuits (and people) from electrical threats on the load side. To meet this relay selection guideline, buy a product with enough dielectric strength and insulation to stop interference or damage.

• Multiple contacts are valuable in a relay if you want simultaneous control of several circuits or a specific sequence of operation. It’s more efficient to do this with a single multicontact relay vs. several single-contact ones.

Types of Relays

Each electric or electrical project might require a different type of industrial relay, contact configuration, or expectation for switching time.

Start your hunt by figuring out which type of relay provides the best combination of these and other factors important to your assembly. The three big ones are:

Electromechanical relays are a well-understood and reliable technology great for general use. Reed relays make sense when you need to combine fast switching in a low-power application. Solid-state relays are what you’ll need when the job requires precise and rapid control.

The more powerful the product, the more durable it is, too. Reed relays have a longer lifespan than electromechanical relays. However, SSR relays beat them both by virtue of having no mechanical parts to begin with.

Overview of Terminal Blocks

Terminal blocks are the professional’s alternative to soldering or taping, offering a convenient way to connect and terminate wires.

The most popular mounting solution for terminals is a DIN rail. This tends to simplify wiring setup and save space in the enclosure.

Along those lines, accessibility is an important feature in terminal block installations. In addition to keeping terminal footprint minimal, consider using screws as your fastening method. These connections are easier to modify and add an element of futureproofing to your assembly.

Besides the usual comparison points, a common way to start your terminal block hunt is to check how many circuits the assembly needs. This determines the number of poles the block must have.

(Tip: With terminal blocks, it’s entirely possible your engineering team will care about only one criteria: compatibility. Many prefer that all terminal blocks in an installation come from the same manufacturer.)

Types of Terminal Blocks

There are many ways to classify industrial terminal blocks:

• Connection method
• Wire-securing method
• By function

Let’s focus on the most common way – connection method. You can learn about the other categories at the button further below.

Barrier strips (aka single-row) terminal blocks are extremely common in the U.S. They consist of three main parts: a plastic or thermoplastic body, multiple terminals, and barriers separating them. A screw or clamp connects the wires, and sometimes a small enclosure or lid protects them.

IEC PCB mount (aka Euro style or wire-to-board) terminal blocks are a staple of, you guessed it, PCBs (printed circuit boards). They work by placing bare wires in the module, where housing and a clamp secures the strands. PCB terminal blocks can be single-, dual-, or multilevel (usually three or four) structures. You can mount PCB blocks either through the board or via pluggable pin strip mounting.

Feed-through terminal blocks feature two input sides (one on each side), where two distinct wires are fed through the housing. They use the screw-in method of connection, coming with predrilled holes. They come in single, dual, or multilevel modules.

Edge connector terminal blocks accept a circuit board edge into their housing. Putting them together matches the copper traces and screws the block into an enclosure. This means the block only needs one discrete female connector.

By understanding how each type works, you can ensure safe connections, make maintenance and troubleshooting easier, and streamline the overall assembly.