How to Wire A 110 Block Telephone Connector

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110 wiring blocks are commonly used for distributing telephone lines in homes and offices. If your home was built after 1990 there's a good chance you have a 110 block connecting your telephone jacks to your incoming phone lines. They're a bit complicated but knowing how they work can wind up saving you a lot of money. In this post we'll go over over the different parts of a 110 block and how to wire your phone system.

My phone company charges a $10 monthly fee for an inside-wiring maintenance fee. By knowing how to maintain my own phone lines I save about $120 every year. A 110 block is an integral part of many home telephone systems so it's important to know how they work.

Alternative Phone Distribution

110 blocks are pretty cool but wiring a 110 can be a bit complicated as you'll see. If you find the instructions below too difficult you can use a Leviton 1x9 Telephone Distribution Board instead. I used it in an previous article. It's a lot easier to install and punch down because you don't have to do any cross connects. You won't have as much flexibility as you do with a 110 block but for most residential installations it should work fine.

If you already have a 110 block installed or really want to use one, keep reading.

110 Block Components

A 110 block consists of a base that gets mounted on a wall (or panel) along with a number of C-Clips that allow you to make connections.

110 Block Base

The 110 Block base can come in a variety of different configurations. You can get them with or without feet or even rack mountable. They're also available in different sizes including 50, 100 and 300 pair configurations plus you can use multiple 110 blocks together if you need to. Each row accommodates 25 pairs of wires. The Leviton 41AB2-1F4 GigaMax 5E 100 Pair 110-Wiring Block Kit is a good choice for many home and small office installations. It comes with everything you'll need including the C-Clips and labels.

You start out by punching your premise (permanent) wiring to the posts in the base. Your premise wiring is the cables that run through out your walls such as the cables that go between your phone jacks and distribution point (green cables) and the incoming phone lines (gray) that connect to the telephone companies network interface device (NID).

Each wire gets punched down to one slot between posts in the base. The posts on the base aren't color coded except for a black marking for every 10th pair.


The base also doesn't create any electrical contacts. The posts just hold the wires in place.

To make a connection you use the connecting clips (C-Clips). C-Clips get punched down over the cables on the base post. C-Clips allow you to punch down more wires on the top of the C-Clip. The C-Clip creates an electrical connection between the wires punched down on the top of the C-Clip and the wires punched down on the base.

C-Clip come in 3, 4 or 5 pair configurations. Each pair on the C-Clip is color coded for each pair, blue, orange, green, brown and slate (gray). Since most twisted pair cable you'll be using is 4 pair you'll mainly be using the 4-pair C-Clips which have blue, orange, green and brown markings. These Leviton GigaMax 5e C-4 Clips work with the Leviton 110 block I mentioned earlier
. I was considering getting the ICC 110 Wiring Block but it didn't come with clips and wound up being more expensive after adding the clips.

Cross-Connect Wires

You obviously are going to want to connect your phone jacks to your incoming phone lines. To do that you use cross-connect wires. They're an untwisted pair of wires that you use to connect one pair of wires in one cable to one pair of wires in another cable. 

You accomplish this by punching down the cross-connect wires on top of the C-Clips for each line. In the image above there is a cross connect pair going from Line 1 in our incoming line to Line 1 on one of our phone jacks.

Wait! But we have multiple phone jacks and only one incoming line. How do you connect them all when you can only punch down one wire in each slot? In the more detailed example on this page we'll go over creating a bridge to attach multiple jacks to incoming lines.

Punch Down Tool

To insert the wires in the 110 block you'll need a special tool called a punch down tool. They come in impact and non-impact varieties. An impact punch down tool is better because it can apply more force with less effort on your part and gives the wire the right amount of force to press it into the connector without damaging it.

Punch down tools have interchangeable blades that commonly have a reversible blade. You can get a 110 blade that has a cutting blade on one end and a non cutting blade on the other or a combination blade that has a 110 blade on one side and a 66 blade on the other. A 66 block is an older style of phone block. They're still used but 110 blocks allow for faster transfer speeds and can be used for networking or voice.

A punch down tool can be a cut or non-cutting blade. The cutting blade will trim off excess wire as you punch down the wire. The non-cutting blade does not trim off the excess wire. It only pressed the wire into place. You'll need a non-cutting blade if you plan to daisy-chain some wires which is common in phone installations. We'll go over that in the example.

I use a Klein Tools Cushion-Grip Impact Punch-Down Tool VDV427-821. I really like it because of the round grip and long tip. It only comes with a combination 110/66 cut blade. For this project a non-cutting 110 blade like this Klien Tools VDV427-015-SEN 110 Terminate/Terminate-Cut Punchdown Tool Blade is also important to have.

110 Block Home Wiring Example

To really get a sense of how a 110 block works let's do an example for a fairly complex residential phone system that includes a home office. (You can use this wiring setup for a small office with 11 phones too.)

The home has 4 incoming phone lines. One main house line, 2 office lines and 1 fax line as follows:
  1. Home Line
  2. Office Line 1
  3. Office Line 2
  4. Fax Line
There will be 9 phone jacks installed throughout the home that are only connected to the home line (line 1). These will be installed in the kitchen, dining room, living room, family room, garage, basement, master bedroom, and the 2 other bedrooms.

Two jacks will be installed in the office. One with the fax line and one with 3 lines. The two office lines and the home line so you can answer the home line if you're working.

In total we have 4 incoming lines going to 11 jacks. This is a complicated setup but demonstrates how the 110 block is wired so you can use that knowledge for smaller or larger systems.

Step 1: Preparation

Run a cable from each wall jack to a central location were you have your structured media panel. This is also where the incoming phone lines will run to as well. Screw the 110 block onto your panel and make sure there's enough slack in the lines to reach the block and leave some extra if you need to make any changes down the road.

Step 2: Punch Down Incoming Lines

On the top row of the 110 block we're going to punch down the incoming lines from the telephone company starting from the left of the block.

Note: Wires are usually run down from the back or bottom of the block but to make it easier to see in this example I'm running them from the sides. Also, when you run your wires set up an anchor point somewhere that allows you to leave a loop of extra wire in case you need to make any changes in the future.

In a Cat5e cable you have 4 pairs of wires and each pair supports one analog phone line. Each line has a different color.
  1. Blue
  2. Orange
  3. Green
  4. Brown
Each pair has a white wire with a colored stripe and a solid colored wire. Example is white-blue and blue for line 1. The white wire is the tip and the colored wire is the ring.

If your incoming lines are using old style wiring there may only be 4 wires (red, green, black and yellow) capable of sending 2 phone lines. Red/green for the first line, black/yellow for the second line. For a 4 line setup there would be two 4-wire cables. 

Using the cutting blade on a 110 punch down tool start punching down the incoming lines starting from left to right in order for each line pair, blue, orange, green and brown. The white wire comes first followed by the colored wire as shown below.

This is the order all the wires will be punched down. White-blue, blue, white-orange, orange, white-green, green, white-brown, brown. If we had old 4 color wires it would be red, green, black, yellow, red, green, black yellow or some other combination. The most important thing is to have the incoming lines properly ordered for lines 1, 2, 3 and 4.

One thing to note. We don't need to have all lines from one source. There could be 2 lines coming from the phone company and 2 lines coming from a VOIP adapter or even all VOIP lines.

Step 3: Punch Down Premise Cables

Next we're going to punch down our premise cables. These are the cables that connect wall jacks in each room to the 110 block. 

We're going to punch these down on the first two rows of our 110 block using the same blue, orange, green and brown layout.

Row 1: Kitchen, Dining Room, Living Room, Family Room, Garage
Row 2: Basement, Master Bedroom, Bedroom 1, Bedroom 2, Office, Fax

The phone premise wires have green jackets based on my residential structured wiring jacket color recommendations. One 4-pair Cat5e cable comes in from each jack.

I added some text and orange boxes to help identify the different cable pairs because it's starting to get a bit complex now. Just remember to follow the blue, orange, green and brown layout with white wires in the pair first. At the end of each row there should be 2 empty wire posts.

When you've punched down all your wires double check to make sure everything is in the right spot then attach the cover, labels and punch down the 4 pair C-Clips on the top 2 rows. They make special 5 pair punch down tools but they're a bit pricey and not something you should need as a DIY'er. You can use your impact punch down tool placed in the center of the C-Clip to punch it down, then punch down each end for good measure.

Step 4: 110 Bridge

Right now we have all our jacks and incoming lines punched down but they're not connected to each other. If you picked up a phone connected to one of the house jacks you wouldn't hear dial-tone. 

We need to connect the jacks to the incoming lines. There's a problem though. Each slot of the 110 IDC connector can only accept one wire. We can't connect all our phones to the C-Clip mounted over the incoming lines. We'll need to create more spots to make connections by creating a bridge.

By daisy chaining 4 pairs of wires (blue, green, orange, brown) through the slots on the bottom 2 rows we can create 11 points that allow us to connect our 11 phone jacks. It's a little complex so we'll start with one pair at a time.

Phone installers will have spools of single pair cross connect wires in different colors but if you don't have those you can just strip the jacket off your Cat5E cable to get the 4 individual colored pairs you'll need.

Note: Try not to untwist the pairs any more than you need to, the maximum allowed for Cat5e is 1/2". For the illustrations I have the pairs untwisted because it's easier to see what's going on as well as easier to draw.

First the blue pair. One thing you'll notice is on many 110 blocks the base posts aren't color coded except for maybe some sort of marking on every 10th pair. This makes it a little tricky which is why I recommended installing the C-Clips on the first two rows after we already punched down the premise wiring. It gives you a frame of reference. After the blue pair is punched down in the bridge the remaining 4 pairs are easier so take your time to get the blue pair right.

Switch to the non cutting end of your 110 punch down blade and start punching down your blue pair wires in the first two posts, white-blue then white. Next loop the wires around, up and down every 8 slots to line up where the blue markers on the cross connects will go and punch them down after you verified their placement.

Repeat the process for the orange pair, punching them down on the two slots to the right of each blue pair you punched down previously as shown.

Finally repeat with the last two pairs and you should have your bridge wiring looking like this.

Verify everything looks right and trim off the ends with the cut side of the 110 blade. Then install the cover, labels and punch down the C-Clips over the last 2 rows.

Alternate 110 Bridge

The above bridge will allow you to send all 4 lines to each of your wall plates. You can also set up the bridge in a way that leaves more room for station cables if you want to add more wall jacks without adding another 110 block. In my situation I'm going to have 3 phone lines. One main house number and 2 VOIP lines that I use for work. My main line will go to all my phone jacks but I only want my VOIP lines to go to a few rooms.

I'm going to be able to punch down my incoming lines and 14 station cables the rest of the block will be devoted to bridges. Line 1 will have 16 pairs, Line 2 will have 8 pairs and lines 3 and 4 will have 6 pairs each.

I used some cut off portions of Cat5E cable so I could color code each bridge.

After I punch down the C4 C-Clips over the bridge wires and add the label strip to the 110 block it's a little more obvious what's going on.

Step 5: Connect The Bridge

All the work we've done so far and yet we still can't make a phone call. Seriously, stop and look at my older phone distribution post for an easier option.

Nope? Still with me? Okay, we have our bridge wired up but it's not connected to the incoming lines so that's what we'll do now. Using 4 pairs of cross connect wires (can just strip jacket off Cat5e cable) we're going to connect the first block on row 1 which has our incoming lines to the first block on row 4.

It doesn't really matter which bridge block we connect it to but it's nice to be consistent. We're going to connect all our row 1 blocks to row 4 eventually and then row 2 to row 3. That will keep the labels clear and make it easy to trace the cross connects in the future. For right now though let's just do the incoming lines using 4 different color pairs for the 4 incoming lines as shown.

Don't untwist the pairs any more than you have to. I did it just so it's easier to see. Run the wires around the outside of the block. Leave a little bit of slack to help trace wires but not too much. Try to keep it neat and looking good.

We now have dial-tone across the entire bridge for all 4 lines! Woohoo! Let's call all our friends and tell them! Hello? Hello? Ooops... We still can't make any calls. One last step before we can.

Step 6: Connect Jacks To Incoming Lines

It was a bit of work getting to this point but now you can see how flexible a 110 block is. We can connect 1, 2, 3 or all of our incoming lines to each jack fairly easily and make changes in the future. If we want to send line 1 to the kitchen, line 2 to the dining room and line's 1&2 to the family room it's simple to do. Let's start with the basics.

Home Phones

We decided to only have one home phone line since babies are born with cell phones these days. Each of the house phones will only have one line, the house line.

All we have to do to make that happen is connect a blue pair of cross connect wires between the blue slots in the jack's C-Clip to the corresponding blue slots on the C-Clip of one of the bridge clips. For neatness mirror the C-Clips so that row 1 gets connected to row 4 and row 2 gets connected to row 3.

First we're going to connect the Kitchen jack.

Starting from the left, white blue then blue on the Kitchen C-Clip to the corresponding slots on the 2nd Bridge C-Clip on row 4. The kitchen phone is now connected to Line 1, the house line. Let's test it out by ordering pizza. We'll be done with the rest of the phones by the time it comes.

Continue doing the rest of the jacks on row 1 of the 110 block. Split up routing the cross-connect wire pairs on both the left and right so it's neater.

Now do the home phone lines on row 2. The cross-connect wires will just go straight down through the center trough. I added arrows so you don't miss them in the mess of wires.


For the fax line we're going to do things a little differently. Like the home phones the fax is only going to get one line but instead of getting line 1 it's going to get line 4. That means we need to add a cross connect wire pair between the brown pair on the Bridge C-Clip (line 4) to the blue pair on the Fax C-Clip. That's because the fax is expecting the line to come in on line 1, the blue pair.


The phone in the office can handle at least 3 phone lines. We are going to connect the 2 office lines as well as the home phone line to this jack.

Office lines 1 & 2 are lines 2&3 in our 110 block but we want them to be lines 1&2 at the phone and the house line (line 1) to be line 3 at the phone. We can do this at the jack or we can do this at the 110 block. Since this article is about 110 blocks, guess where we'll do it? :)

Line 1 (blue) on the bridge goes to line 3 (green) on the Office clip
Line 2 (orange) on the bridge goes to line 1 (blue) on the Office clip
Line 3 (green) on the bridge goes to line 2 (orange) on the Office clip

We're finally done. Just in time too. Pizza's here!


  1. Fantastic explination and illustrations

  2. Is that old Soviet technology ?

  3. Can a 110 block be used with CAT 3 wire? We have a duplex with 5 runs per floor. All the RJ12 telephone keystones have been wired the same. Your Fax line example makes sense in this case for 5 runs. We installed two CAT 6 patch panels for the cable internet runs in both units but how would you suggest wiring a 110 block if a tenant requires Telephone Internet?

  4. Great reference! Thank you.

  5. Wow, great article! Nice job..

    Just wanted to drop in one of the things I like to do. I like to use the following 110 patch cords. I've only seen them from Panduit, not sure if others make them. For the home where people may not have a punch tool, or want to keep extra wire around, they are very nice. I just buy a handful and keep them hanging on the 110block. You just patch in whatever you want, one pair at at time. If someone needs to change it later, they don't need any special tools..

  6. Tom, I love your exlpainations and illustrations, thank you so very much for investing the time to make these for all us who are using them.

    I am wondering if you could post a picture of a completed alternate 110 block bridge which I prefer to do. I just want to make sure I can understand how to use the alternate bridge method correctly. I am fairly new to this, so I figured I would ask for some help from you. Thank you kindly, Jon

  7. Hi Jon,

    The regular bridge you alternate a different line so it would go blue pair, orange pair, green pair brown pair. You wind up with all the pairs having the same number of pins you can connect to premise wires (phones).

    Let's say you have 11 phone wall jacks you're installing. All of those will get line 1 so you can create a bridge with 11 (for extensions) and 1 extra (for jumper to incoming lines) for a total of 12 pin pairs connected in the line 1 bridge. You can even do a total of 16 so you have a few extra for the future. If you have a second line but you know it's only going to a couple of places (like a fax machine) you can make a smaller bridge of 4 (3 extensions 1 incoming) for that. Or you can do it with 16 for line 1 16 for line 2.

    The alternate way of making a bridge you can have all the line bridges have the same number of pin pairs or different. It's also easier to understand visually because all the lines for the bridge are grouped together.

    With the alternate bridge layout you keep the lines together so you basically wind up with as many bridges as you want. If you only have one phone line you can just do one bridge of lets say blue pair. If you want to set up for 2 lines you make 2 bridges and you can make them have as many pins as you want.

    For me my main line 1 was going to all the phones, the other lines were only going to some of the phones so to save space I created a big bridge of line 1 (blue) and smaller bridges for lines 2-4 and I used different colors for the pairs to help identify them as well as created a label to indicate them. It's helpful if the total number of pairs in the daisy chained bridge across all lines is in multiples of 4.

    The pictures are pretty much complete. The first picture shows the wires on the bottom of the 110 block. Then the second picture shows the block with the clips punched down and the labels inserted. If that's not clear I also have this video which describes how I did my alternate bridge on a 110 block and at the end I show how I test to make the bridge works.

    If you have a specific question I can answer that might be easier but hopefully the above helps.