Marne and Associates NESC and OSHA Newsletter addresses issues relevant to power and communication utilities.

In This Issue:

• Question 1: Overlashing a New Communication Cable
• Question 2: NFPA 70E and Utility Workers
• Live Web Seminar: Arc Flash Hazards and Fire Rated Clothing
• New Software Programs Available

We are overlashing a new communication cable to an existing cable and messenger bundle. The power utility is asking us to provide strength calculations. Is this required by the NESC?

Any addition or modification must meet the NESC requirements. Lashing an additional cable will reduce the clearance above ground. The additional cable will also add more weight to the line and increased surface area for wind loading. Clearance and strength requirements should both be checked carefully.

Pole strength can be calculated by hand, or by using software designed for calculating loading and pole strength, such as O-Calc. Figure 1 shows an example pole in the O-Calc program.

Fig. 1 - Screenshot of a pole setup in O-Calc

Do the arc flash requirements of NFPA 70E apply to utility workers?

The requirements of NFPA 70E do not apply to utility workers; however, the soon-to-be-released OSHA power worker rules do list NFPA 70E as one method to comply with the new OSHA arc flash requirements. Also, the NESC requires that all utilities perform an arc flash hazard assessment by January 1, 2009. The NESC, OSHA, and NFPA 70E also reference IEEE Standard 1584 for performing arc flash calculations.

If you're struggling with the different standards and codes related to arc flash hazards, you may want to check out our upcoming live web seminar, Arc Flash Hazards and Fire Rated Clothing, which discusses which standards apply to electric utilities.

Arc Flash Hazards and Fire Rated Clothing

Need help meeting the Jan 1, 2009 deadline for the NESC® arc flash rules? Join our 90-minute live web seminar which is offered once a month from August to December. More info.

New Software Available

Marne and Associates is now offering the following software available through our Code Store:

• O-Calc: a program for calculating structural loads from Osmose Utilies, Inc.
• Pull-Planner 2000: a program for cable pulling tension calculation and conduit system design from American Polywater Corp.
• IEEE 1584: an industry standard for arc flash calculations, including Microsoft Excel worksheets, from IEEE.
• SpanCheck: a free program for checking clearance above ground from Marne and Associates, Inc.