Electrician Gainesville GA
Currently, the alternative to a complete electrical systems analysis is utilizing NFPA 70E’s tables. The tables serve as a guide for equipment less than 600V in order to prescribe the proper PPE and set general flash protection boundaries. The NFPA 70E tables constitute a “blanket” approach to arc flash analysis but do serve a vital need: providing generalized information for equipment on which a hazard analysis has not been completed. This method is the direct application of Table 130.7(C)(9)(a) from NFPA 70E. It is intended to be a conservative application of the principles of Annex D, without the need for performing a complete arc flash evaluation and study. However, the tables are based on several assumptions:
1. For panelboards and switchboards rated 600V and less, the available fault current is 25kA, and the clearing time of the protective device is 0.03 seconds (two cycles);
2. For 600V class motor control centers and other such equipment, the available fault current is 65kA, and the clearing time of the protective device is 0.03 seconds (two cycles);
3. For insertion or removal of starter buckets in motor control centers as noted above, the available fault current is 65kA, and the clearing time of the protective device is 0.33 seconds (20 cycles); and/or
4. For 600V class switchgear containing fused switches or power circuit breakers, the available fault current is 65kA, and the clearing time of the protective device is 1 second (60 cycles).
Problem is that the assumptions listed above are not necessarily applicable to the systems you may be analyzing.
If the table footnotes are not properly observed the required PPE may be inadequate to protect the worker; too little PPE leaves workers inadequately protected, and is therefore undesirable. In the more likely case, the PPE requirements will exceed what is actually necessary, potentially causing heat stress, hindered visibility, and restricted movement.
Careful study of the footnotes will reveal also certain equipment configurations which necessitate a complete analysis. Finally, the 70E tables cannot utilize device-specific equations and therefore cannot accurately characterize the performance of all protective devices.
Here is some actual verbiage from two citations that a client in New York received from OSHA during an OSHA inspection of their small plant in NY. They are located basically “Out in the middle of nowhere” according to the client and they were shocked that the inspection occurred. They had no accidents, and had no involvement with OSHA prior to a OSHA representative showing up on their doorstep. The inspector walked through their plant an spoke with some employees back in August of last year. In January, the received three citations, with a short time period to resolve those issues to “Abate” the fines.
Here are the exact OSHA verbiages of two of those issues:
ITU is on the scene there today and throughout this week to resolve these issues for them…
They specifically site NFPA 70E and 1910.331 through 1910.335.
Citation 1 Item 2a Type of Violation: Serious
1910. 132(d)(1): The employer did not assess the workplace to determine if hazards were present, or were likely to be present, which necessitate the use of personal protective equipment (PPE):
(a) Throughout the facility, on or prior to 8/26/11: Hazard assessment(s) did not address electrical hazard(s) which may necessitate the use of personal protective equipment to protect employees from arc flash hazards. Arc flash hazards may be encountered during maintenance or similar operations.
Abatement note: The hazard assessment and personal protective equipment selection should be based on the recommendations listed in NFPA 70E “Standard for Electrical Safety in the Workplace”, Article 130, Table 130.7(C)(9) “Hazard/Risk Category Classifications and Use of Rubber Insulating Gloves and Insulated and Insulating Hand Tools” and Table 130.7(C)(10) Protective Clothing and Personal Protective Equipment.
Pursuant to 29 CFR 1903.19(d), the employer must provide certification to OSHA that this violation has been abated within 10 calendar days of the “Date by which Violation Must be Abated”.
Date By Which Violation Must be Abated: 02/20/2012
Citation 1 Item 2b Type of Violation: Serious
29 CFR 1910. 332(b)(1): Employees were not trained in and familiar with the safety related work practices required by 29 CFR 1910.331 through 29 CFR 1910.335 that pertained to their respective job assignments:
(a) Throughout the facility, on or prior to 8/26/11: For all employees performing electrical work on equipment where electrocution or arc flash hazards may be present.
Pursuant to 29 CFR 1903.19(d), the employer must provide certification to OSHA that this violation has been abated within 10 calendar days of the “Date by which Violation Must be Abated”,
Date By Which Violation Must be Abated: 02/20/2012
