What is a "Bridge Tap" fault?

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If you have an NBN service, and there is a suspected fault, you might be advised that the service has been tested by NBN and the result is that NBN has detected a ‘bridge tap’.

A ‘bridge tap’ is the name of a type of fault that is returned when NBN’s equipment senses (via very sensitive and complex electrical measurement techniques) that there is an irregularity, abnormality or inconsistency on the physical cabling or wiring inside of your home.

The reason for the diagnosis can be pretty varied, but the most common cause is the phone sockets inside the house have been wired in a ‘star’ topology. In this configuration, all phone sockets are connected back to a single central location. While this configuration works well for traditional voice services, the electrical characteristics of such a wiring configuration can cause problems with newer technologies like FTTN (which rely on sending very high frequency, high bandwidth signals down sometimes very old copper!).

The result for services where a bridge tap is detected can be varied, and can include dropouts or poor performance, or other undesirable behaviour.

Regardless of the source or the symptoms, a ‘bridge tap’ diagnosis just indicates that NBN’s equipment has measured some sort of irregularity or abnormality in the physical wiring inside of your home, and it is the responsibility of the home-owner to repair this.

The easiest and quickest way to have this repaired is to get an ACMA-accredited cabler to disconnect all the sockets in your home, cutting-off any unneeded and unnecessary internal cabling, and leaving just the first phone socket for your NBN modem.

If this isn’t successful, you may need to consider having an ACMA-accredited cabler replace your internal wiring completely.

Want to know more? Our friends at All Point Communications have written a great technical article on bridge taps, which can be found here.

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