What’s a bridge tap?

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Bridge tapping is a telecommunications connection where extra wires are run for future flexibility. However, it can cause interference and problems with high-speed data transmissions. A technician can determine if a home has a bridge tap and may need to cut the line to fix the issue.

A bridge tap is a type of telecommunications connection common in residential neighborhoods, where the telephone company will run more wires than necessary to add flexibility in the future when it needs to assign and reassign service. While this is convenient for the telecommunications company, it can cause problems for the customer, as bridged connections can cause significant interference, especially with high-speed data transmissions. Customers experiencing repeated problems with line interference that are not resolved with tactics such as filtering may wish to discuss the possibility of a bridge tap with a telephone technician.

When telephone companies draw lines to establish connections, their goal is to make it easier to service customers in the future. They can run a long telephone wire and use bridge tapping, if necessary, to connect various customers to that line as people move in and out of a community. Historically, multiple people were connected to one line, in the party line setup, where households shared a phone number. With multiple lines, the company can provide full service to a neighborhood and easily switch lines as needed to accommodate changes.

In a bridged configuration, only one house is connected to a given line, but significant interference can occur. The extra line length can generate interference, depending on the length and location of your active telephone connection. This can cause problems with services such as digital subscribed line (DSL) Internet service, which can be subject to interference. The line may also crackle or pop as people use the voice connection.

A bridge tap is often visible. Customers may be able to pinpoint the length of the line and can see that it runs continuously past the connection to their pole. On older utility poles it is important to be careful of older lines; when a line goes down, the phone company can put in a new one without removing the old one, in which case a tangle of wires can create a misleading look from the ground.

A telecommunications employee can determine if a home has a bridge connection. Physical inspection can reveal the wiring used at the pole and junction box, and line testing tools are also available. Customers experiencing chronic Internet connectivity and voice line issues may need to explore a number of causes before determining what is causing the problem. A telephone technician may suspect a bridged connection after ruling out several other common options and may fix the problem by cutting the line, rather than allowing it to continue past the family with service.

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