by Simcona on Jul 17, 7:59:01 PM
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When it comes to connecting electrical systems, there are DIY-grade solutions, and there are professional solutions.
Terminal blocks are the more sophisticated version of soldering or taping, offering a convenient way to connect and terminate wires.
There are many ways to classify terminal blocks; the most common ones are connection method and wire-securing method. By understanding how each type works, you can ensure safe connections, make maintenance and troubleshooting easier, and streamline the overall assembly.
Let&#;s run through each terminal block type you might come across in industrial projects so you&#;re prepared to design or source wisely.
- By Connection Type
- By Securing Method
- By Function
- Other Types
What to Expect in Any Terminal Block
Sure, you could splice or tape twisted wires together, but what if you have several wires that need joined nearby? Or several outgoing wires that need to connect to a single incoming wire?
In many electrical and electronic applications (like control panels), terminal blocks are a must for neat layout and quick identification.
All connection blocks have an insulating body that houses a current-carrying bar or strip and provides a base for the clamp. The blocks usually receive power carried via wire conductor from a larger source.
The most common mounting solution for terminals is DIN rail, as it tends to simplify wiring setup and save space in the panel or cabinet.
As for the specifics of choosing terminal blocks, it&#;ll depend on whether you&#;re using them for power distribution, control, or another function in the assembly.
Different products have different:
- Voltage ratings
- Current ratings
- Wire size/type
- Pole count
- Pitch
Terminal Block Styles by Connection Type
Barrier Strips
Easy to spot all over North America, barrier (aka single-row) terminal blocks consist of a plastic or thermoplastic body with multiple terminals separated by barriers. Terminals can use either a screw or clamp to secure wires (more on that later). Barrier terminals sometimes include a small lid or enclosure to protect the cabling.
Barrier terminal blocks provide individual wire termination points, allowing independent connections for each wire. As such, common uses include:
IEC PCB Mount
IEC PCB (printed circuit board) mount terminal blocks, aka Euro style or wire-to-board blocks, originated from IEC assemblies. These components work by placing bare wires in the module, where housing and a clamp secures the wire. IEC-style blocks are typically short PCB solder connections.
PCB terminal blocks can be single-, dual-, or multi-level structures (with the latter usually containing three or four levels). Pay attention when specifying PCB terminal blocks, as they come with one of two mounting options:
Feed-Through
Feed-through terminal blocks are at their best when they create multiple wire-to-wire connections. By managing a large amount of wiring, they conserve space and better organize the assembly.
This terminal block type features 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 for securing them into place.
Like their PCB mount cousins, feed-through blocks come in single, dual, or multilevel modules.
Edge Connectors
This type of terminal block works by accepting a circuit board edge into its housing. Putting them together matches the copper traces and screws the block into an enclosure. There&#;s no soldering necessary with this block type.
Some electromechanical designers swear by this block type because of their low cost of ownership. Since the circuit board itself serves as the male part of the connection, edge connectors require only one discrete female connector. Edge connectors are also pretty durable relative to their initial price.
Edge connectors are common in:
- PCBs
- Expansion slots on computers for peripheral cards
- Your old Nintendo game cartridges!
Terminal Block Types by Securing Method
You&#;ve probably already noticed a few different ways terminals can secure the wires they&#;re charged with protecting. There are others too &#; in fact, some buyers and manufacturers categorize terminal blocks by securing method rather than the buckets listed above.
Because there are several wire-securing systems, and some have an annoying number of alternate names, let&#;s walk through these categories as well:
Screw Terminals
This is the most common way to secure electrical wires in a device.
These terminals consist of a metal or thermoplastic body with a clamping mechanism that secures wires using screws. This design enables a reliable connection by tightening the screws, which compresses the wire against a metal contact within the block.
These terminal blocks accommodate a wide range of wire sizes and are suitable for commercial and domestic wiring carrying moderate electrical currents.
There&#;s also a physical aspect to their application: They can handle the physical stress of mounting multiple wires up to 250 kcmil each in the same area. Screw terminals are made of steel and other strong materials so they can support connection of heavy wires.
Spring-Cage Connection
You may know the spring-cage connection terminal block by one of its million or so alternate names:
- Spring-loaded
- Spring-clamp
- Quick-connect
Spring terminals work similarly to terminals that rely on screws. However, instead of tightening a screw to connect a piece of wire, a preloaded spring clamps pieces of metal together.
Most of these terminal blocks require the user to attach the wire to a ferrule via spring release before insertion. Some spring-clamp terminal blocks require a small screwdriver for attachment, though a specific torque isn&#;t necessary.
One reason spring-cage terminal blocks are popular is that they require less skill to use. They offer savings on assembly time, on top of having a reasonable sticker price. However, the connections are less secure than those using screws.
Common uses include:
- Small wires (they work particularly well here)
- Vibration-heavy environments
- Industries where wiring changes are frequent
- Controller interconnection in small spaces
Push-In
As if spring-cage connectors weren&#;t confusing enough, meet another close relative(s)! Push-in terminal blocks are non-ferrous metal components that come with their own set of alternate names:
- Push-fit
- Push-on
- Push button
Push-in terminal blocks also allow for a simple connection and fast installation. The user simply inserts the conductor into the clamping unit.
Just like spring-loaded types, push-in terminal blocks work best when the connecting wire has a ferrule. Where these terminal block types are different is the release method &#; push-fit release devices are attached right next to the wire insertion spot.
Popular use cases include:
- When you need 600 V capacity, but also a thin design
- Marine environments
- Chemical plants
- Applications with frequent changes &#; you can release the conductor tool-free
IDC
Insulation-displacement connector terminal blocks are also called IPCs (insulation-piercing contact). IDC terminal blocks are common in applications that call for mass termination:
This unusual technique involves mechanically forcing unstripped, unprepared wires into slots inside the block. The assembler then adds pressure, causing sharp metal contacts to pierce the insulation and create electrical contact.
Engineers use IDC terminal blocks as a cost-efficient means of making a high number of contacts. Installation is quick and eliminates the need for a separate wire-stripping operation.
This terminal block type was once a subpar fit for stranded wire, but nowadays you&#;ll find manufacturers offering IDCs for both solid and stranded wire.
Terminal Block Types by Function
There are many key electronic components that go hand-in-hand with terminal block use. They serve similar functions in:
- VFDs (variable frequency drives)
- PLCs (programmable logic controllers)
- I/O (input/output) blocks
- Sensors
Let&#;s look at some other special cases where the setup may look a little different.
Ground
Ground terminal blocks operate much like a screw terminal. However, instead of connecting wire-to-wire, the terminal connects an incoming wire to solid ground.
The wire terminates at the mounting location of the block. For example, in DIN-mounted ground blocks, the rail acts as a busbar and distributes ground potential to other ground terminals on that rail.
If you want to learn more, please visit our website Wired Terminal.
These connection terminals are widely available in single-, double-, and three-level format at vendors like Weidmüller.
Fuse
Fused-connection terminal blocks put overcurrent protection in-series, between the wire-in and wire-out spaces. This eliminates the need for external fuses, adding flexibility to your layout and current level.
Naturally, this type is ideal for designs that specifically need fuses for overcurrent protection. Certain versions are built for use in potentially explosive areas.
Multilevel versions are also available. Some manufacturers have even created variants with indicator lights so users can see the fuse&#;s condition.
Thermocouple
Thermocouple lead connections aren&#;t compatible with your everyday terminal blocks. Instead, they use special thermocouple blocks.
If a metal thermocouple wire touches a dissimilar conducting material inside a standard block, it creates unwelcome voltage. Thermocouple terminal block designers have come up with two options for avoiding that hazard:
Eliminating the metal connection strip, instead clamping leads together on both sides of the block
Using a connection strip, but matching its metal type to the wire&#;s
Power Distribution
Power distribution terminal blocks are notable for their need to carry high current levels. Even more so than other connection types, their primary goal is safety.
These blocks come in various sizes and materials to suit your application. No matter the type, they come with heavy-duty contacts that can withstand long-term vibration or load surges.
Molded Case Circuit Breaker
Molded case circuit breaker (MCCB) terminal blocks have a unique design, featuring two separate terminals that facilitate contact from either side of the block.
These terminal blocks are also safety-first, but are specific to MCCB applications. They improve contact resistance between circuits and reduce risk of electric shock or fire in:
Other Types of Terminal Blocks
Yes, there are even more ways designers, manufacturers, and purchasers sort out terminal blocks. Consider the value these features could bring to your assembly:
Pluggable Wire-to-Housing
Most terminal connections involve the wire going directly into the housing. Pluggable terminal blocks are the exception.
While they still include wires inserted into a housing, pluggable blocks add the benefit of modular housing you can insert directly into a circuit board. They use a plug and receptacle to form a quick connection.
Plug-in terminal blocks are valuable in cases that might require hot-swapping. Along these lines, they add convenience to assemblies that need frequent disconnection, as they keep users from having to disconnect wires individually.
Various Wire Orientations
Industrial terminal blocks are available in three common wire-entry orientations:
Horizontal (90°)
Vertical (180°)
45°
The physical dimensions of your overall design often determine which wire orientation &#; and terminal block &#; you should choose.
How to Select a Terminal Block?
In most industrial electrical assemblies, terminal blocks are an upgrade over sloppy solutions like tape and twisting. Terminal connections look professional and perform like a professional.
As you&#;re specifying them for your next projects, be careful. There are many types, and many more names. Some have the same characteristics, while others will give you very different results.
The top factors to watch for are:
Size
Current & voltage ratings
Layout
Number of circuits needed (indicates the # of poles the block will need)
Environmental performance
Futureproofing (ex.: screw connections are easier to modify)
Cost
Do they come from the same manufacturer (likely the only factor your engineers care about)
Watch out for a future blog post on choosing the correct terminal block from a distributor based on your application. For now, check out our current resources (get it?) or, if you&#;re ready to buy, browse a manufacturer list:
Terminals and connectors are implemented to connect wires and cables to pieces of equipment in an electrical system. They can be used for new installs or when replacing older connectors. If you have bent connectors, cracked terminals, burnt or cracked connectors, or any terminals with damage then it's time to replace them with something new. Not only will you find the terminals and connectors you need but we also carry all the proper tools needed to install any of these products. Most likely, you're going to need at least some wire crimpers . We offer the best types of crimp connectors out there. Seriously, OEMs come to us for our wire connectors. Now that we've covered the basics, let's look at what types are available.
We understand that no two jobs are alike and as such, a variety of parts and tools are needed to give the best possible solution. That is why Pacer carries a range of wire terminals and connectors. This way you find what you need when you need it. Each type of terminal or connector we carry is something we feel people need access to. Many sites will carry one or two types of electrical wire connectors but are they really offering solutions or just trying to make a sale? By carrying more than we need to, we are offering the greatest number of solutions and ensuring that you find what you need. Take a look below at some of the more popular styles we carry.
These connectors are designed for use where cable-to-cable circuits need to handle harsh conditions. One major advantage of environmentally sealed connectors is that they are field serviceable. No need to cut, strip, and re-terminate wires in order to repair a connection. With these electrical connector types, you simply disengage the locking mechanism, pull them apart, make your changes, and reconnect them. It really is that simple. This is one of many reasons you&#;ll find these in industrial applications.
This type of connector is used to safely connect one or more wires to another wire. There are a variety of styles depending on what the task at hand is. If you simply need to replace a section of wire, a regular butt splice will work. In some cases, you may need to connect two smaller gauge wires to a larger one. In that situation, you would want to use step-down butt splices. Utilizing butt splices reduces the number of wire connectors to crimp. Remember, pay attention to the conditions your connection will need to endure and use that to help select the right type of insulation for your project.
are the most secure type of tongue-style wire terminals. That fit cleanly over a stud and are held in place by the locking nut. The advantage of ring terminals is that they remove the possibility of terminal slippage you may find with other types of terminals. These are a common choice due to their durability and ease of installation. They are easy wire connectors to crimp. Depending on the application, you can connect multiple wires to a single ring terminal or connect multiple ring terminals to a single stud.
We carry these types of wire terminals in two options, locking and flanged. These are a useful type of electrical wire connectors in environments where you may need to make adjustments without having to fully remove a screw. When using forks to connect one or more wires to a stud, you want to be confident that it will not come loose. Commonly in an electrical environment, vibration can loosen holding screws. To combat this, we recommend flanged forks which snap around the stud creating a solid connection, or locking forks which grip the nut also creating a solid connection. This way you know that you've created a solid connection that will not come loose.
These wire terminals are designed for use where the electrical connection is intended to be connected and disconnected multiple times. This is why disconnects are a preferred choice when it comes to field serviceability. They offer superior holding force due to the indentation of the tab of the female part locking into the hole in the male part. This type of connector is known for being simple wire connectors to crimp. Their ease of use makes them a solid choice. Even though they are built for disconnection and reconnection, they are equally built for permanent placement. If you plan to leave them on as a permanent option choose the insulation type that best supports the environment where you will be placing them.
are commonly found in use with compression type terminal blocks. What this means is that many terminals blocks use screws to hold a wire in place. The issue is that many people have to deal with an electrical system that uses stranded wire not solid. When you tighten a screw down on a of tiny wires, the individual wires become frayed or weakened. This can lead to long term issues. The solution is to use a pin terminal in order to consolidate the wires into the equivalent of a solid wire. These are an effective choice when it comes to electrical wire connectors. Now when the screw tightens, the force is applied equally, and damage is avoided.
are similar to ring terminals in that they connect to a stud through a circular opening. Lugs, however, are much more durable and are usually meant for either larger gauge wire and cable or for harsh environments where corrosion is an increased risk. These are high-quality, durable electrical wire connectors. Think about it, you wouldn&#;t use a ring terminal to connect a car battery. You would use something specifically meant to handle a tough environment. When considering wire connectors to crimp, always factor in the level of protection needed. In order to be as effective as possible, lugs need to be tough and conductive. That&#;s why all the lugs we carry are made from high quality copper for the highest level of conductivity.
vary in their design much more than most other types of wire terminals. You have everything from snap-in connectors to twist-on electrical wire connectors and even some that require soldering. That&#;s due to the fact that coaxial connectors are used in a wide range of applications. This means that they need to be versatile to meet a range of needs. They are used in everything from radio transmissions and digital broadcasting to even microwave industries. These are specialized wire connectors to crimp and may require specialized tools. Before selecting the connector you need, make sure to be aware of the specific usage and the type of mating the connector will need to offer.
These connectors are used to create a permanent seal. That means that they have to be built with durability and longevity in mind. Compression seal connectors are used with coaxial cables, but their installation process is vastly different. Compression tools are used on these wire connectors to crimp them correctly which guarantees the permanent seal mentioned above. This keeps the electrical wire connectors from ever coming off or being pulled out. All Pacer compression seal connectors are made from machined annealed brass and coated with an anti-corrosion nickel plated finish.
This type of electrical wire connectors are used to connect a load to a battery. In order to give the highest level of conductivity, all Pacer battery posts are made from 131 contact copper. We use this type of copper as it is 95% pure making it highly conductive. Specialized tools may be needed to work with these wire connectors to crimp them correctly. One issue that plagues a lot of battery posts is that they can get corroded over time which causes a range of problems. To prevent this, each post is electro-plated with a bright tin finish. For an added layer of protection, you can add a boot covering to your post. This will help to extend the life of the connection.
When you work with terminal blocks, using the non-terminated end of stranded wires as a connection point will lead to fraying and weakening of the connection. You want to consolidate your stranded wires into one singular point of connection. This is where wire ferrules come in. They create a superior connection to a terminal block. By consolidating the wires into the ferrule, you minimize your risks of the connection fraying or coming loose. This, in turn, creates a stronger connection. These are simple wire connectors to crimp given you have the proper tools. When considering wire connectors to crimp, always factor in the tools required.
The insulation wire terminals carry has a significant effect on the environments they can handle and their overall longevity. Pacer carries many wire terminals in four insulation options; heat shrink, nylon, vinyl, and non-insulated. This way you can get the wire terminals you want in the insulation you need. Heat shrink offers a range of advantages which is why it is a popular choice. For starters, epoxy lined heat shrink creates a moisture-proof barrier that will prevent corrosion from damaging your conductors. This is especially important in marine environments. Heat shrink terminals also offer more flexibility and abrasion resistance meaning that will last longer than other styles in most conditions. Another benefit of heat shrink terminals is that they are translucent. This means you can easily visually inspect your crimp to make sure the connection is strong. Nylon terminals, in many cases, are can be double crimped. This is where the crimp on the wire is strengthened by a secondary crimp on the insulation. This gives the connection a stronger hold and longer life. Nylon terminals are semi-translucent which means that visual inspection of the crimp can verify the connection. Vinyl terminals are the most cost-effective insulated option. They are available in a wide range of styles and are a very common choice when looking at wire connectors to crimp. Non-insulated terminals are the least expensive, however, they offer the least amount of protection. One strong point of non-insulated is that the crimp is easy to inspect. In certain circumstances, solder can be added to strengthen the connection and create a better seal. All our electrical wire connectors are built with durability in mind.
Are specialized tools required to use these terminals & connectors?
When dealing with your electrical wire connectors, the electrical system, or its components, the correct tools are an absolute must. Without the proper tools, you run the risk of improper usage and eventually malfunction. Knowing this, Pacer takes steps to carry the tools for all the wire terminals or connectors we offer. This way you&#;re never left wondering how to use a particular item. Find the tool you&#;re looking for here. Of course, with such a variety of terminals and connectors, there is going to be a variety of tools to accompany them. We have taken steps to make the selection process as easy as possible so you can get the parts and tools you need and get your project completed. When looking at the right wire connectors to crimp for your project, always consider the proper tools.
What are terminal boxes used for?
Terminal boxes are used in a variety of ways such as field service where a range of terminals is needed on hand or in work trucks where quick access to terminals speeds up production. This makes them ideal for both new wire and existing terminal installations as well as when replacing parts. Terminal boxes have multiple compartments for various terminals so you can have forks, rings, splices, pins, and more, all easily separated and organized.
What compliance's do these terminals & connectors meet?
Pacer strives to offer the greatest amount of solutions possible. To offer solid solutions, they have to be backed up with evidence. That is why we put so much effort into carrying products that meet or exceed industry compliances. Below you will find a blanket list of compliances for each type of the connector or wire terminal we offer. You have to understand that compliances and standards can vary greatly from one type of wire terminal to another type of wire terminal even in the same group. All the electrical wire connectors we carry are built to last. We are confident of our products and stand behind the compliances they carry. Feel free to contact a Pacer expert with any specific questions you have about the compliances and standards our parts meet.
Coming Soon
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