Your open meter is a critical piece of equipment and correctly used will save you and the company time and money and cut down on customer frustration. Following are typical uses:

The primary use of an open meter is to find the terminal or pedestal where the cable pair is open when a customer complains doesn't have dial tone. When the open meter is connected to the cable pair and properly programmed capacitance is converted to feet or meters, the field technician goes that distance, opens the terminal or pedestal and restores service. He may miss the location by a pedestal or a terminal, but a quick measurement puts him spot on.

Experienced technicians also use the open meter to identify the presence of water in a section of air core PIC. They then use a Time Domain Reflectometer (TDR) to determine where the water is in the section when doing thorough section analysis. This information helps the field technician to build a business case to get the cable section replaced.

They also use the open meter as a companion meter with the resistance bridge and the TDR to identify anomalies in a faulted section of cable that skews the information such as unknown laterals, load coils, slack loops, and gauge changes within the faulted section.

A skilled field technician can also identify a split cable pair with the open meter and then apply identification tone to determine the cable pair that is split with his cable pair.

Following are some rules to abide by when using an open meter:

- Open meters convert all capacitance to feet or meters including the capacitance of any lateral, bridged tap, pots splitter, filter, network, or build out circuit.

- When measuring the distance to an open cable pair and the tip and ring measurements are different, use the shortest measurement. The longer measurement is inaccurate.

- When measuring open cable pairs in non working cables with an open meter designed for measuring opens in working cables the measurements will be short of the actual distance to the open. This is because pairs around the pair that you are measuring build up a false shield that skews the measurement. For accurate measurements 12 other pairs within the sub-unit must be working or grounded.

- The ground that you connect to must be good and connected to the shield to give accurate measurements.

Keep the above information in mind when measuring open cable pairs and your success ratio will increase making your job easier.

There are several brands of good open meters on the market today. Most multi-functional test sets contain an open meter function. Different engineers have their own take on how to convert capacitance to feet or meters. Most brands do a good job, but because of different techniques different meters read subtly different. If you are considering purchasing an open meter for the first time or replacing old meters remember that if you base your decision on budget, you may make an expensive mistake. Keep in mind the E's: Experience, Expectations, Existing Equipment.

If you want to talk about available meters, feel free to call me at 831.818.3930 or email me at dmccarty@mccartyinc.com.