Marne and Associates, Inc.
Experts in Electrical Code
| NESC® and OSHA Newsletter | January 14, 2009 |
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Marne and Associates NESC and OSHA Newsletter addresses issues relevant to power and communication utilities.
In This Issue:
Applying the NESC to Day-to-Day Utility Work Applying the National Electrical Safety Code® (NESC®) to Day-to-Day Utility Work provides a general overview of each part of the NESC and focuses on practical examples and applications. The class includes time for questions and is rich with graphics. Understanding the NESC® rules is a must for personnel responsible for operating a safe utility system.
The first session of this four part series is scheduled on January 21, 2009; however, you can also begin in February and attend the first class when the cycle repeats. Question #1: What clearances are required by the NESC above ground for typical transmission line voltages (69KV, 115KV, etc.)? NESC Rule 232B and NESC Table 232-1 give clearances for lines operating up to 22KV phase to ground for an effectively grounded system. For lines operating at more than 22KV phase to ground, NESC Rule 232C contains adders for voltage and elevation. NESC Rule 232D may also be applicable. The required clearance above ground for a transmission line will depend on the voltage at which it operates and the elevation at which it is installed (See Fig. 1). McGraw-Hill's National Electrical Safety Code (NESC) 2007 Handbook Figure 232-21 contains an example calculation including these adders.
Question #2: Have the new/updated OSHA transmission and distribution rules been released? If not, do you know when they will be released? Changes to OSHA 1926 Subpart V and 1910.269 have not yet been released. They were originally intended to be published in 2008, but the record was reopened for comment so that some errors in the approach distance tables could be corrected. The most recent unified agenda shows the the record was reopened on 10/22/2008 and the comment period ended on 11/21/2008. The current status listed is "Analyze Record" with a date of Febuary 2009. We expect the OSHA rules for power transmission and distribution will be published this year.
Pull-Plannner 3000 is now available.
Pull-Planner™ 3000 for Windows™ (an update to Pull-Planner 2000) calculates cable pulling tension and sidewall pressure around bends using the pulling equations. Tension estimates are useful in designing conduit systems and planning cable pulls. Such planning can save time and money by minimizing splices, vaults, pulling set-ups, etc., while ensuring installation tensions that won't damage cable. NESC Rule 341A2 states that pulling tensinos and side wall pressures on supply cables should be limited to avoid damage.
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 The live web seminar series Applying the National Electrical Safety Code (NESC) Rules to Day-to-Day Utility Work is a four part series beginning in January adressing an overview of the NESC and the rules most commonly encountered in day-to-day work.  Purchase McGraw-Hill's NESC 2007 Handbook the NESC from the Code Store.  Marne and Associates also provides expert witness services relating to the National Electrical Safety Code and OSHA. |
If you have a question for our newsletter, please send an email to kirstin@marneassociates.com with a concise description of your NESC or OSHA question. We attempt to answer every question received, but the volume and type of questions limits us.
Disclaimer: The content of this newsletter should be considered general information only. It is not intended to be consulting engineering advice, legal advice, or an official interpretation of the NESC® or OSHA requirements.
The information and diagrams contained in this document attempt to show common situation where the 2007 NESC Code applies. They are intended to be used as visual aids to the reader of the Code and are not intended to be a replacement for the comprehensive nature of the Code as it is written.
The figures and/or photos used in this document were derived from McGraw-Hill's NESC® Handbook by permission of the publisher, McGraw-Hill Companies, Inc.
Copyright © 2008 Marne and Associates, Inc.
