Maximum Ethernet Cable Length
So, you bought that 1,000 foot box of Cat6 Ethernet cable and intend to run the entire box from your house to your barn or guest house. “This will be great!” you are thinking. “I can finally shuttle off that annoying relative to another part of my property and they can surf the Internet all day….without bothering me!” you tell yourself.
Don’t start packing up your relative yet. That idea won’t work.
You have to take into consideration the maximum ethernet cable length that can be run, and it does not matter what Category of cable you get because they all have a maximum length of ethernet cable.
Here is a quick table for your reference.
Huh. Seems like we have a common denominator—328 feet is the maximum “channel” length of an Ethernet cable run. So don’t get any ideas; Cat6A will have the same maximum length of ethernet cable as Cat6.
Before we go too far down the technical rabbit hole, we need to define what a channel is. An Ethernet channel is the complete end-to-end connection of a cable run from a router/switch to something you use like a computer. Of course, there are variations on this theme, but suffice it to say that from powered-device to powered-device the maximum ethernet cable length is 328 feet. This is assuming your ambient temperature is 68 degrees F or below, and you are using solid copper Ethernet cable with a conductor gauge of 22 to 24 AWG. More on the temperature and solid copper conductor things later.
There are ways to get devices connected that are much farther away, but they don’t make use of the same segment of cable channel.
The patch cable as a channel theme
Here is an example of a super simple channel, at maximum ethernet cable length:
In the above example, a very long cable with RJ45 connectors (also called plugs or ends) is attached to both ends of the cable. This example is two things:
- An Ethernet patch cable. By definition, an Ethernet cable that has RJ45 plugs on both ends is a patch cable.
- The Ethernet patch cable is functioning as the channel
For the typical DIYer, this is how most installations will look. A large number of people assume that a Ethernet cable has RJ45 plugs on both ends and this is how Ethernet cables are supposed to be connected to your stuff. Why? Well, most folks have not seen anything different.
The permanent link as part of the channel theme
The permanent link is typically seen as:
- Female keystone jack to female keystone jack (those things that mounts in your wall plate, looking for all the world like a big telephone jack)
- Patch panel to female keystone jack
Permanent links are typically used in commercial installations, or installations done by savvy DIYers desiring flexibility and clean looking installs. You see, permanent links are typically solid copper “structure” cable that runs inside walls, below floors, in your basement, and typically out of sight. The only thing you see is a wall mounted keystone jack at one or both ends.
A permanent link becomes a channel when you plug in an Ethernet patch cable into both ends of it, and at one end you have a smart TV or computer and at the other end you have a network switch.
Here is an example of a channel that contains a permanent link:
Wow! Ok, things just got more complicated. Take your imagination with me on this one. In this example above, there is a permanent link installed from your living room to your far bedroom where your WiFi is always horrible. You know that room I am talking about! At both ends of the permanent link are female keystone jacks. That link is “permanent” because you have no intention of ever moving it again.
From each keystone jack is an Ethernet patch cable connecting up a device that gets power. At one end, your patch cable is plugged into the WiFi router you got last holiday season. At the other end in the far bedroom, you have a second patch cable connecting the other keystone jack to your smart TV you got the holiday season the year before that.
Did the rules around maximum ethernet cable length change? Nope. From end to end, including the patch cables, how long can ethernet cable be? You are still limited to 328 feet. This means you can have variations like this:
In each scenario above, the maximum distance for a channel is used, and that happens to be 328 feet, assuming certain conditions.
Those certain conditions:
- The permanent link maximum is limited to 295 feet at 68 degrees F. This length gets shorter as ambient temperatures rise, and can be offset by using shielded cable to some extent. See Temperature's Effect on Ethernet Cable Length. The maximum of 295 feet is also assuming you are using patch cables with 24 AWG conductors. Again, permitted length gets shorter if you do something different.
- You should not use stranded patch cables longer than 75 feet, and you can read more here about why: Solid vs Stranded Ethernet Cable. In the case of stranded patch cable that makes use of 28 AWG conductors (ultra thin patch cable), you should not exceed 49 feet, even if the patch cable is serving as the entire channel as in the first example above.
You heard that right: Your entire connection from router to PC (for example) is limited to 49 feet if you use a 28 AWG patch cable. This will be discussed in a future blog.
- When using permanent links, your patch cables and keystone jacks need to be all of the same Category!
- To throw a wrench into this whole thing, your maximum length of ethernet cable can also be affected by EMI/RFI. Sometimes you need to use shielded Ethernet cable as discussed in Shielded vs Unshielded Cable. and you may need to reduce distances if your cable is subjected to heat above 68 degrees F as discussed in Temperature's Effect on Ethernet Cable Length.
Based upon the limits and other rules, you can see a huge number of ways to run Ethernet in your home or business despite the maximum ethernet cable length. Which path you take is often dedicated by budget, skill level, environment, and more.
So, there it is. A potentially confusing topic made easier to understand! HAPPY NETWORKING!
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