Standard Interpretations - Table of Contents|
| Standard Number:||1910.137(b)(2)(i) ; 1910.269(a)(3); 1910.269(c); 1910.269(l)(1); 1910.269(l)(2); 1910.269(l)(3); 1910.269(l)(4); 1926.951|
Depending on the configuration of the system, an employee could be isolated from two of the phases on the pole by approaching one of the outside phase conductors and working on it from a position where there is no possibility of coming too close to the other two phase conductors.Scenario #2: A worker is in an insulated aerial device and approaches a multiphase primary distribution circuit from underneath the conductors. Once the rubber insulating equipment is installed, the worker will move into a position to perform tasks that will require him or her to be between the covered conductors. Although the conductors are covered, contact with either the rubber gloved hand, parts of the body covered with rubber insulating sleeves, or uncovered parts of the body is possible because of the close proximity of the conductors.
The use of tools and equipment results in a composite insulation system composed of the tool(s), equipment, and air gaps. When air gaps are in series, the resultant dielectric strength can exceed that of the tool or equipment itself, but it cannot be determined from direct addition of the material thickness and air gap sizes.Consequently, unless testing has been performed to determine the rating for a particular combination and configuration of insulation and air gap sizes, at least one of the air gaps or layers of insulation must be rated for the voltage between two parts for the insulation to be considered sufficient for the voltage involved. In short, in the absence of testing, the insulating properties of two individual pieces of insulating material are not additive. [ back to text ]
|Standard Interpretations - Table of Contents|
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