| 6PxC and 8P8C are the "technically correct" terms used to refer to six pin and eight pin modular jack and plug hardware used for both voice and data connections. Six pin position hardware is commonly available that only has connection points (and pins) for two or four wires. Six pin hardware is correctly referenced as 6P2C (6 pin positions/2 connections), 6P4C, or 6P6C depending on how many connection points are available, or using the generic 6PxC designation for any six pin hardware. I am not familiar with any eight pin hardware that doesn’t support eight wire connections and every reference I know of uses the "8P8C" nomenclature. | |
Comparison of |
   
|
So, what jacks should you use and how should you connect the wires?If adding to an existing installation, the simple answer is "match the existing."For new residential installations, I recommend using 8P8C jacks with 568B configuration for data and dual 6P4C or 6P6C jacks for voice and DSL, with four-pair cable terminated as two RJ14 jacks, with pairs 1 and 2 on the first jack and pairs 3 and 4 on the second jack. Using dual RJ14 jacks lets two or more lines be connected so that they can be accessed most easily. For example: If two lines are available, at the wiring hub line 1 is cross-connected to pairs 1 and 4 and line 2 is cross-connected to pairs 2 and 3; a single line device connected to the first jack connects to line 1; a single line device connected to the second jack connects to line 2; two line devices can use either jack. For three or more lines, the cross-connects would be done as best suited your needs. Of course, if using a wiring block as your wiring hub, you can use different cross-connect arrangements for each jack according to your needs, as illustrated on my page about adding a third line. If you are using a fancy residential "structured media center" as your wiring hub, then your flexibility will be constrained by the options available on the bridging modules used in the center. Most structured media centers don't allow a great deal of flexibility when used with more than one line. There are more advantages to using blocks instead of a media center than just saving money. I generally recommend terminating as many pairs as possible on all jacks. That is a significant advantage if you decide to add more lines on previously installed jacks, because the wires will already be connected to the jacks. Believe me, it's frustrating to have to re-work all of the jacks in a home to add a second or third line. Connecting the unused pairs also provides additional strain relief for the cable and avoids having to decide whether to coil or clip the spare wires. That is why I only stock 6P6C voice jacks. Does all of that really matter? My answer is yes. Using the wrong terminology can lead to confusion and unnecessary expense. Want a longer cord for a two-line phone? If the package says RJ11, better make sure it really has 6P4C plugs and two-pair cable, or you might be making another trip back to the store. No big deal, except gas is getting pretty expensive. However the problem can get worse. Suppose you're setting up a small business in your basement and need three phone lines on three desks. You buy a three-line phone for each desk and you order three phone lines. Then you decide to have one of your employees oversee the jack and cable install because you're busy and can't be there when the install is done. You give the employee a note for the tech ordering the lines be connected to RJ11 jacks at three locations. If the tech doing the install has an order to install an RJ11 jack at three different desks, he'll naturally assume single line service (RJ11) at each desk. He might use two-pair cable from the demark to each location, since only one pair would be needed to support single line service and the tech probably has several boxes of old two-pair cable he's trying to use when possible. When he's done, everything will be done as per the order. However, when the three-line phones are connected to the jacks, they will each only have access to one line, each different from the other, and the intercom functions won't work, since they use frequency modulation of one of the voice line pairs to transmit the intercom signals. However, if the tech doing the install has an order to install three RJ25 jacks at three different locations, he should understand that all three jacks need all three lines and everything should work fine when he's done. And if not, you have a legitimate complaint with the tech. But, if the problem resulted from you requesting the wrong type jacks, then the tech is not a fault and you'll probably have to pay for the correction or do it yourself. If two-pair cable was used for the initial job, having the tech come back to change three RJ11 jacks to three RJ25 jacks would probably cost as much as the initial install, to say nothing of the time and frustration. What's the difference between RJ11 and RJ25? In this scenario, at least about $300 for tech time, 16 hours of lost productivity from the two people you just hired, a full day of lost sales, and a day of frustration. So the standard for jacks is that there are a lot of standards and you should pick one based on your preference and what type lines and equipment you expect to use. | |
|
One last note: JACKS and PLUGS: Jacks are "female" devices, normally found on walls or and on equipment. Plugs are "male" devices, normally found on line cords. Hopefully, the ramifications of confusing jacks and plugs when making purchases are obvious! | |
