Terminal Block Basics

Terminal_Block_Basics.pdf

We have all seen this type of wire connection: exposed twisted wires - Does it work? Yes. - It allows electricity to flow - It is NOT safe. It’s messy and unreliable. An improvement on that connection would be a wire nut and wires. We are all familiar with wire nuts. They are very commonly used to make electrical connections. - They provide much more safety - They are more secure. - Not terribly organized, but get they job done. An even better solution would be a terminal block. It functions no differently that the two examples I just showed you, except that: - Commonly used in industrial and commercial applications - It is much safer - More secure - Allows for more connections options - And gives us the ability to keep our wire much more organized.

Types of Terminal Blocks

There are several different types of terminal blocks that can be used to accommodate different situations, uses and applications. 

Single Level Pass through terminal block

Just like the wire nut, this type of terminal block is simply used to connect two wires together with a common junction point. This is helpful when a component needs to be disconnected or we simply want to isolate something within the circuit. These are the most common types of terminal blocks you will see in industrial applications.

Ground Terminal Blocks

Look and function and function almost exactly like most pass through terminal block with one exception. They are grounded. These blocks and a metal connection from where the wire is terminated all the way to the bottom of the block where it will clamp into the panel. This allows us to ground an electrical circuit without have to run a wire to the main ground connection on a breaker or surge protector

Fused terminal blocks

These functions in a very similar manner to the basic pass through terminal block with one exception. There is a fuse located in the terminal block. This fuse allows us to protect items that we are wiring so that they do not encounter to much voltage or current.

Multilevel terminal blocks

Just like with a basic pass through terminal block, the multilevel terminal block allows for an electrical connection, or junction point. The advantage to using a multilevel terminal block is that it can make 2 or 2 electrical connections in the same block.

Also, this block can incorporate fuses, and have the ability to be ground. So, in some cases these blocks can be a combination of all the other blocks we have talked about. Disconnect Terminal Blocks Similar to a fused block, the disconnect allows us to stop the flow of electricity by lifting this lever on the terminal block. Unlike fuse blocks, the are a more permanent solution, but will not provide any protection in the event of a power surge.

By doing this the metal will no longer be in contact and no electricity will flow. Safety is one of the main reasons terminal blocks are used. The connections points are very secure, and the design does not allow for short circuits or shock hazards to be a common occurrence. They are very durable. This is why they are the preferred connection method for industrial use. They can stand up to harsh environments. They give us the ability to isolate components, sensitive instrumentation, power, etc.

Transcript:

[0m:4s] Hello I'm Josh Bloom, welcome to another video in the RSP Supply education series. Today's video, we want to talk to you a little bit about terminal blocks. But to better illustrate what a terminal block is and how they actually work, we want to start with something that's probably a little bit more familiar to the people watching the video today.
[0m:19s] We simply have two wires that are twisted together. Does electricity pass through this? It absolutely does. Does it work? Yes, is it safe, not really? Is it going to be secure or hold together. Not really. If I give that a little bit of tug it's going to come right apart. Not a great connection, but it works. One step up from that, something that might be an improvement or a little bit better, we've all seen this before. Again, we have two wires, but this time we have a wire nut, commonly seen in your home or in any kind of commercial or industrial building. Same thing happens here. We have current passing through, electricity works, this is definitely much safer, it's going to be a lot more secure. So this will work. But today again, we want to talk to you about terminal blocks, which is going to be
[1m:2s] a more industrial type of connection. Just like with the other two connections, we have two conductors coming in. We have a connection point, it's very secure, it's safe, commonly used in industrial applications, and it is going to be one of the best types of connections that we can use for industrial control cabinets like you see here. So now that we have a basic understanding of what a terminal block looks like and is, I want to show you several different types of terminal blocks that are commonly used in the industry. We're going to start with what we've already seen, which is a single level pass through terminal block. In this type of terminal block we're going to have a conductor coming in this side and another conductor leaving this side. Just like with the wire nut, it's simply going to allow electricity to pass through, there's no way to disconnect power or to protect anything on either side of his terminal block. This is the most commonly used type of terminal block.
usually used to distribute power within a control panel, also can be used for signal connections. The next type of terminal block that you'll see commonly is a ground terminal block. Obviously looks very different as far as color goes from the single level pass through, but in shape and form very much the same. The major difference with a ground terminal block is it will ground connections within your industrial control panel. It also grounds the terminal block itself to the mounting or Dinrail on the industrial control panel. The next type of terminal block we want to talk to you about today is a fuse block. The fuse block, much like the single level, is going to allow electricity to pass from one side to another. The main difference is we have a fuse in this block. You can see the fuses on this little flap here. If I plug that in, that will now allow electricity to flow up and through that fuse. The other thing that's different about this terminal block is I can disconnect power by lifting this lever. So I have the ability to cut power in two different ways, by disconnect, or if that fuse blows if we have too much current electricity passing through. The next type of terminal block, we want to talk to you about today is a multi level terminal block.

[2m:58s] In today's case, we have a two layer, or a two level terminal block. The bottom layer, just like with a single level is just a pass through there's no ability to disconnect, refuse that connection. So we have one conductor coming in one side, simply going out the other. The top level is going to act much like the fuse terminal block. We're going to have one conductor going in we're going to have electricity coming up passing through the fuse and it will go out through the other side. Just like with the fuse terminal block, I can disconnect power by pulling the fuse out, or if we have too much current or electricity, passing through, the fuse will blow protecting any components that we might have connected to this terminal block.

[3m:35s] Now that we've talked about a few of the different types of terminal blocks, we want to discuss why we might use terminal blocks, and one of the biggest reasons is for safety purposes. When we have operators inside industrial control panels, we want to make sure we have very safe connections where we don't have any exposed wire or termination and terminal blocks allow us to accomplish that. Another reason we use terminal blocks is they're very durable, which is why they are used in industrial applications. And, one of the biggest reasons we use terminal blocks is for organizational purposes. As you can see here, we have an industrial control panel and you can clearly see that we have a lot of different wire terminations and things happening here. But what we do have is a very clean
organized way to identify the types of wires we have safe connections. You can also probably see, we have a lot of the different terminal blocks that we've already discussed in this video. First you can see here we have a single level terminal block also here. In this particular instance, this terminal block is allowing power to come through the top and out at the bottom and it is actually powering a few of the different components within this panel.

[4m:36s] The next type of terminal block that we've talked about was the ground terminal block. In this particular application, we have one main ground wire coming in and then we have several different components that have grounded on those terminal blocks.
[4m:49s] You can also see we have several fuse blocks in this panel. These particular blocks are distributing powers throughout the panel. So you can see here, we have one main DC wire panel coming in,
[5m:2s] and that is distributing power to several different components throughout the panel.
[5m:7s] Lastly on the bottom you can see here we have various different types of multilevel terminal blocks. In this case, the reason we are using multilevel terminal blocks, these are
connected to instruments that would be out in the field, and those instruments require two different types of wire. So we have a wire going out to the instrument and then we have a wire coming back into the instrument. So we require both of those levels on that terminal block. That saves a lot of room within the control cabinet. You can also see these terminal blocks are fused as well, so we can actually disconnect or protect those instruments that are wired. As you can see, we've covered many different types of terminal blocks and the different uses and applications for each one. As always, you can find any of the products seen in this video on our website. for more information or other training videos, please go to RSPSupply.com, the Internet's top source for industrial hardware.