How To Choose The Right Terminal Block For Your Project

A terminal block is a modular, insulated block used in electrical connections to join wires. It is much more efficient, and safer, than taping wires together, and easier than soldering. However, these blocks vary in size, structure, and design. So, how do you choose the right terminal block for your project?

There are several things to consider, to ensure better performance, practical efficiency, and of course, safety. Here are nine things to look at when choosing a terminal block, so you make the right choice.

9 Things To Consider When Choosing A Terminal Block

To simplify this for your future reference, we have categorized the factors into electrical, mechanical, and safety considerations.

Electrical

1. Current Rating

Your electrical requirements are the most important factors to consider particularly your current rating. If a terminal block operates at a current that is too high, overheating and damage to the connection will occur.

To avoid this, select a terminal block with a higher current rating than the system’s expected maximum current. 150% is a good bet.

2. Maximum Voltage

Voltage surges can damage the connection. To avoid this, choose a block with a maximum voltage rating greater than the maximum system voltage.

3. Wire Sizes

Wire and cable sizes are the measurements of their cross-sectional areas, indicated by gauge numbers, with higher numbers used for thinner wires. The wire size measurement units differ between North America and Europe. Ensure you understand the wire sizes you are working with:

• North Americans use the American Wire Gauge (AWG) to indicate wire size.

• Europeans indicate wires’ cross-sectional area in square millimeters.

Mechanical

4. Orientation and Fit

You can arrange terminal blocks in various orientations, for example horizontally, vertically, or at a 45-degree angle. The orientation you select depends on available board space, but should also offer the most accessibility to the block when in place.

The DIN Rail (metal rail used for housing) must also fit well within the available space, with enough clearance above and below. Take the bend radius of the wires being connected into account. Remember that accessories like jumpers, end covers, and end brackets must fit the DIN rail specs.

5. Block Structure

There are three primary terminal block structure types. These are single-feed-through, dual-level, and triple-level terminal block structures.

• A single-feed-through terminal block is ideal for simple wire-to-wire connections.

• A dual-level terminal block consists of two levels of connection terminal stacked on top of each other, allowing an increase in current capacity.

• A triple-level or multi-level terminal block consists of three layers of the connection terminal, which is ideal for situations where you need multiple wire connections.

6. Wire-Securing Method

The three main wire-securing methods to choose from are:

• Screw-in terminal blocks are suitable for stranded or multi-core wires. A fastened screw clamps the wire in place in the terminal block. Although time-consuming, it’s a reliable method for securing wires, and easy to disconnect when necessary. However, excessive vibration may loosen the connection.

• Push button-style terminal blocks are best for single-core wires. With this method, a push button opens a spring-operated clamp that holds the wire in place. This is a quick and easy method of securing wires, and it is more resistant to the effects of vibration.

• Push-in style terminal blocks, usually used for single-core wires, operate very similarly to the push button method. With this method, you insert the wire directly into the terminal block, activating a spring-operated clamp to hold it in place. This wiring method is quick and easy, and best for harsh industrial environments.

Safety

7. Compliance Ratings

Just as you check your electrical enclosures for NEMA ratings, you should check terminal block specs for UL or IEC safety standards. You should see one or the other, or even both. Ensure that your terminal block rating is compliant with your overall safety system requirements.

8. Quality

High-quality components are built for harsh industrial applications and are more likely to last. They’re also safer and more likely to comply with safety ratings. You can be more confident about compliance by purchasing all your components from reputable manufacturers or authorized distributors.

9. Customized Color Coding

Color coding can eliminate the need for labeling, offering identification at a glance and therefore faster diagnoses of connection faults in the future. Choose a color system that works for you. You can use different colors to identify AC or DC input/output, signify high current or voltage, etc.

Conclusion

When selecting a terminal block, consider current rating, maximum voltage, and wire size. Decide on the best block structure, orientation, and wire-securing method for your needs. Check for safety rating compliance, and consider color coding for easier identification.

And purchase only from reputable manufacturers or their authorized retailers/distributors. When you buy your electrical components and accessories from AEC, they are reliable, durable, and designed for the demands of the industrial environment.