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In order to make your own ethernet cables (or modify ones you have), you need quite a few tools to get the job done correctly.
If you’re crimping your own cables, you may have:
- A crimping tool
- An ethernet cable stripping tool
- RJ45 connector boots
- An ethernet cable testing device
In addition to the items above, you’ll also need RJ45 connectors (also called ethernet cable connectors) for any crimping job you do.
Of all the tools needed to crimp an ethernet cable, RJ45 connectors cause the most questions.
The most common question surrounding these connectors is if they can be reused or not.
In other words, if you remove a connector from one cable, can you attach it to another cable? Or if you remove a connector to shorten one of your ethernet cables, can you reattach the same connector to the end of it?
There’s good and bad news here.
RJ45 connectors cannot be reused once they’ve previously been attached to another cable. With that said, RJ45 connectors are very inexpensive, and you can buy them online or your local electronics store for an affordable price.
In this post, I’ll break down everything you need to know about why you can’t reuse RJ45 connectors, as well as your alternatives if you need to replace one.
How is an RJ45 connector attached to an ethernet cable?
In order to understand why RJ45 connectors can’t be reused, you first need to understand how they’re attached to cables in the first place.
RJ45 connectors are attached to cables through a process called crimping.
When you crimp an connector onto an ethernet cable, a few different things are happening at the same time.
The copper wires are joined to the RJ45 connector pins
The first (and most important) thing that happens during crimping is the copper wires inside the ethernet cable are joined with the metallic pins on the RJ45 connector.
Let’s slow things down here a bit.
Inside an ethernet cable, there are 8 copper wires.
These 8 wires make the ethernet cable work as intended. Data is sent through these wires from one end of the cable to the other in the form of electric signals.
The next piece of this is the RJ45 connector.
The RJ45 connector needs to take the electric signals from the 8 copper wires and transfer them to the device its plugged in to.
In order to accomplish this, you might notice that RJ45 connectors have metallic pins on them.
These pins transfer the electric signals from the wires in the cable to your devices.
For your information, if you look closely at the ethernet ports on your devices, you’ll also see metallic pins.
When these pins are in contact with the pins of the RJ45 connector, the electric pulses from the connector are able to travel to the ethernet port of the device.
The pins on the RJ45 connector and ethernet port basically serve as extensions to the copper wires in the ethernet cable.
So yeah, the pins are a pretty big deal. Without them, your ethernet cables wouldn’t be able to transfer their information to your devices.
The reason crimping is so important here is because the crimping process is what connects the wires in an ethernet cable to the pins of the RJ45 connector.
How ethernet cable wires and RJ45 connector pins are joined
As I mentioned, the crimping process connects the 8 wires inside the ethernet cable with the pins on the RJ45 connector.
It’s important to understand how that happens, because it gives us good background when answering the question if RJ45 connectors can be reused or not.
Let’s start with a connector that’s never been connected to an ethernet cable.
Here’s what it’ll look like:
Everything looks normal there, right?
As you can see, there are 8 pins. There’s one pin for each wire in the ethernet cable. Below each pin is a channel that each of the copper wires in the cable fits in.
When you look at the RJ45 connector from the side, you’ll notice that the gold pins on the connector are a little raised.
If you look a little closer, you’ll see that on the bottom of each of these pins is 3 prongs.
These prongs are used to pierce into the copper wires of the ethernet cable during the crimping process.
During crimping, a crimping tool is used to push the pins down into the wires beneath them.
After the crimping process, the pins won’t be raised like they were before.
On top of that, you’ll see that the prongs from the pin are now going into the wires beneath them.
This is what ensures a good connection between the wires and the pins on the RJ45 connector.
Ok, that covers the first part of the crimping process.
Now let’s talk about the other action that happens during crimping.
The RJ45 connector is clamped onto the sheath of the cable
The other action that happens during the crimping process has to do with the protective sheath of the cable.
When a connector is crimped onto a cable, it’s clamped onto the cable’s sheath. This action prevents the RJ45 connector from separating from the cable.
Here’s what it looks like after the crimping process:
As you can see, the pointed plastic piece has been pressed onto the cable. This makes it much harder for the connector to get ripped off.
If the connector and cable were only attached to each other by the connector’s pins and the wires of the cable, the connector could get ripped off the cable. This would cause the wires inside the connector would break.
Clamping the connector onto the outer sheath of the cable helps prevent this from happening.
Can an RJ45 connector be reused?
Now we have a good understanding of how RJ45 connectors are connected to ethernet cables through crimping.
With this information, we can clearly answer whether RJ45 connectors can be reused or not.
To put it simply, the answer is no.
Once they’ve been crimped, RJ45 connectors can’t be reused.
The main reason for this has to do with the pins on the RJ45 connector.
As I mentioned above, the pins on an RJ45 connector are raised before they’re crimped. These pins are pushed down and clamped onto the wires beneath them during crimping.
Once these pins are pushed down, there’s no way to clamp them on a new set of wires. In other words, the crimping process is irreversible when it comes to RJ45 connectors.
I actually learned this the hard way when I first got my crimping kit.
I wanted to see how my crimping tool worked, so I put an RJ45 connector into the tool and pressed down.
Upon removing the RJ45 connector from the crimping tool, I realized my mistake.
The pins on the connector were pushed down.
As a result, I couldn’t insert the copper wires from the ethernet cable as far into the RJ45 connector as I needed to. The pins that were pushed down were blocking the wires.
If you’d like, you can even test this for yourself. Use your crimping tool on an RJ45 connector that isn’t attached to a cable. You can actually see the pins of the connector being pushed down by the crimping tool.
If you look closely, you can see the 8 pins pushed down at the end of the connector.
The bottom line here is: once you’ve used a crimping tool on an RJ45 connector, it can’t be reused.
What should you do if you need an RJ45 connector?
Finding out that RJ45 connectors can’t be reused probably isn’t the best news.
It’s not all bad news, however.
If you need an RJ45 connector for an ethernet cable, you have a few good options.
Buy spare RJ45 connectors
If you’re going to be crimping your own ethernet cables, you’re going to need RJ45 connectors.
If you can’t reuse the connectors you have, what are you supposed to do?
You can find RJ45 connectors online or at your local electronics store. They’re inexpensive, and they usually come in packages with multiple connectors.
The best thing to do is buy a bunch of connectors so you always have some fresh ones on hand when you need them.
It might not be as easy as reusing the connectors you have, but it’s still pretty easy.
Buy new ethernet cables
If you don’t envision yourself crimping a lot of cables in the future, or you don’t want to keep an inventory of RJ45 connectors, you have another option.
You can just buy new ethernet cables when you need them.
This might be a good approach if you have a connector break and you just want to replace it, but it won’t solve your problems if you want to build your own custom ethernet cables.
On top of that, if you replace multiple ethernet cables just because they have a broken RJ45 connector tab, it’ll cost you more to buy replacement cables instead of buying a crimping kit and fixing them on your own.
If you need connectors, I recommend you just buy some spare connectors instead of buying brand new cables. It can save you money in the long run.
With that said, if you take good care of your cables and you don’t need any that are custom lengths, you can probably get away with just buying new cables when needed.
It all depends upon your unique situation and what’s best for your home network.
Let’s go over what we’ve learned today.
You can’t reuse RJ45 connectors after they’ve been crimped.
You can, however, buy replacement RJ45 connectors that you can use any time you need one.
If you have any questions about the information in this post, or you’d like to share your experiences with replacing ethernet cable connectors, please feel free to drop a comment below.
If this information was helpful to you, check out some of these other posts on similar topics: