Article 14

Counting Cable Maintenance Hours

The fundamental goal of a cable pressurization system is to prevent service outages caused by moisture intrusion. The costs associated with achieving this objective vary, depending upon system designs, the type of cable pressurization equipment installed, and maintenance efforts. In today's cable pressurization environment there is a strong emphasis on controlling the maintenance hours associated with cable pressurization. That's why any discussion of labor hours inevitably raises some important pressure-related questions that need answering—questions such as:

  1. How many labor hours does it take to adequately maintain a cable pressurization system?

  2. Am I "gold-plating" one office at the expense of another?

  3. If I reduce labor hours by 20%, what happens to my pressure system? What happens if labor hours are increased by 20%?

In answering these questions, two common denominators come into play: sheath mileage and labor hours. Investigations have shown that a system can be maintained with 0.7 labor hours per sheath mile per month. An office with 100 pressurized sheath miles of cable, for example, could be maintained with 70 labor hours per month.

This 0.7 labor hours per sheath mile per month figure provides a "bull's-eye" at which to direct maintenance activities. It has also proven to be both a realistic and achievable target. But the 0.7 labor hour per sheath mile goal has also raised some additional questions. Richard, who has the Moncton Exchange in his area, was part of a team that spent about four years investigating the various options available to upgrade NBTel's cable pressurization monitoring system. Eventually, after doing a field trial with Flow Finders, the team selected the monitoring package offered by System Studies, which included PressureMAP, 289H LSS monitors, Dial-a-Ducers, High Resolution Transducers, and Flow Finders.

The Unknown Factor
Getting a handle on the hours associated with cable pressurization maintenance has always been tough. Total maintenance hours consistently have been an "unknown" in the management of a cable pressurization system. But without this knowledge, the pressurization budget has been easy to cut, resulting in build-up and letdown cycles. Without knowing what was considered optimum, an individual manager's decision to direct maintenance efforts would often result in a gold-plated district butting up to a district where cable pressure was non-existent.

Labor Hour Goals
Establishing a benchmark for directing labor hours is critical in maintaining an ongoing and efficient pressurization program. The first step toward this goal is to determine an accurate labor hour per sheath mile per month figure. As previously mentioned, 0.7 labor hours per sheath mile per month is considered optimum. This number is multiplied by the total pressurization sheath miles in a wire center to determine how many hours per month are required to maintain the system. It is important to mention that the 0.7 labor hour figure applies only to the maintenance of a system, not the building or construction of a pressure system. Labor hours will be understandably high when the system is being built. Consequently, labor hour per sheath mile calculations should not begin until the system is installed and operational.

In order to get a clear picture of what monthly cable pressurization maintenance should be, the labor hour count should include:

Obviously, the categories attributed to cable pressurization maintenance hours can be modified. For example, some areas contract out dryer maintenance, while in other areas transducer "opens" or pair trouble are counted as wire trouble, not pressure trouble. The key is to be consistent in measuring labor hours within a specific district or tracking area.

Analyzing the Data
One of the most frequently asked questions that arises when measuring cable pressurization labor hours is, "Once hours are being tracked, what does the information tell me?" First of all, it can tell you a great deal about the condition of the pressurization system if the total hours per sheath mile figure is compared with an index that reflects the quality of cable protection, such as PressureMAP's System Quality Index (SQI). The standard or optimum SQI value for an office is 80. Any number above 80 indicates gold-plating; a number below indicates that improvements are needed.

Note that a relatively large number of hours per sheath mile could be justified in an office that is considerably below standard, protection-wise. If an office has an SQI of 50, for example, it may not be unreasonable to spend 2.0 labor hours per sheath mile per month to raise the index. But if the index does not improve after a period of time, something else may be wrong. The office may require partial reengineering or maintenance training may be needed. In contrast, if you have an office with an SQI of 80, you don't necessarily need to spend 0.7 labor hours per month or more in the office. If both labor hours and the SQI are high, maintenance efforts should be curtailed.

When analyzing data it is also important to look at maintenance hours over a period of time. Management decisions based on a monthly analysis of labor hours are seldom accurate. Looking at labor hours per sheath mile on a month-to-month basis might indicate a trend, or flag a particular office for investigation, but it really only provides part of the picture.

For example, a major air dryer overhaul in a small wire center could substantially increase the labor hours for a particular month. Construction activity, resulting in a high number of pressure and flow alarms, will also adversely affect labor hours. When maintenance efforts are analyzed each month, these "temporary" situations will confuse the true assessment of maintenance production.

Also, a change of seasons, with the associated temperature variations, can have a drastic effect on pressurization dispatching. This is another reason why it is advisable to compare labor hour figures from a three month period with those of the same season from a past year.

The Issue of Size
Another major concern when totaling labor hours is the size of offices. People who have large offices say it's easier to maintain small offices. The cable routing is less complex, and it is much easier to access manholes in smaller offices. The people with the small offices complain about windshield time. Sometimes it takes hours to get from one job to another.

So, which is more difficult and should there be two index values? Examination reveals that there really should not be different bogies. We have found that a large number of hours per sheath mile usually points to inefficient use of labor hours. There is one exception, however. Offices with less than 15 sheath miles of cable generally use more than the 0.7 hours per month. Obviously, some wire centers are so small that by the time you get in the truck and fasten your seat belt, you've blown your hour allotment.

Before You Get Started
Recognizing the relationship between pressurized sheath miles and labor hours per month is important when building a new cable pressurization program or upgrading an existing one. By taking a "snap shot" of the number of pressurized sheath miles and the labor hours required to maintain the system, it is possible to project the number of hours that can be saved by initiating the new system. Check out the numbers below.

Labor Hour Calculations

In this situation, a savings of 160 hours per month or 1,920 hours per year can be projected if labor hour efficiency reaches optimum. On the other hand, it would be hard to justify undertaking a major pressurization project if the quality of the system were up to standard and it was being maintained with 0.7 labor hours per sheath mile per month.

Another advantage of taking an initial look at sheath mileage and labor hours is that you can prioritize your engineering efforts. By knowing which area or wire center is using the most maintenance hours per month, you can determine which one is in greatest need of updating.

Hopefully, the information presented above will help you to determine where maintenance efforts are required in your area and where labor savings can be found. Tracking labor hours per sheath mile per month and analyzing SQI data brings not only helps you concentrate and optimize your maintenance activity, it also provides valuable information for assessing possible equipment, training and reengineering needs.

If you would like additional information regarding labor hour efficiency, please contact us at (800) 247-8255, (831) 475-5777 or by email at

© 1996-2016 System Studies Inc. All rights reserved.
(800) 247-8255 | (831) 475-5777