Lately there has been a rash of incidents involving flashes and contacts with primary voltage. The incidents occurred due to improperly written switching orders or missed switching steps, none of which were recognized by the workers involved with the tasks. These types of errors have long been a problem and continue to result in numerous injuries and fatalities.
In April 2014, OSHA’s revised 29 CFR 1910.269 standard was published. This was the first revision to the standard in 20 years, and one paragraph in particular that was clarified was paragraph (m), “Deenergizing lines and equipment for employee protection,” which addresses system operations. As of the OSHA update, the employer is now obligated to appoint an employee to be in charge of the clearance issued by the system operator; this employee will have control over and oversight of all switching that affects the performance of the system.
Specifically, OSHA has promulgated the following rules.
If a system operator is in charge of the lines or equipment and their means of disconnection, the employer shall designate one employee in the crew to be in charge of the clearance and shall comply with all of the requirements of paragraph (m)(3) of this section in the order specified.
The employer shall ensure that all switches, disconnectors, jumpers, taps, and other means through which known sources of electric energy may be supplied to the particular lines and equipment to be deenergized are open. The employer shall render such means inoperable, unless its design does not so permit, and then ensure that such means are tagged to indicate that employees are at work.
Electric utilities must establish a clearance – also referred to as an “open air gap” – on all known sources of the system and source voltages. A clearance also should be used to disable all automatic switchgear to ensure that all system voltage has been isolated from the work area. This procedure is regulatory language and required to protect employees. Tags shall be applied to all open points to indicate that employees are at work and nothing shall be re-energized.
Many past accidents have occurred because multiple crews or companies were working on the same equipment without proper clearance, or because tags and system grounds were shared without proper coordination by system operations. In each of these accidents, circuits were inadvertently energized before all clearances and sections of feeders were ready. Crews may be working on a switched-out section and a circuit may be energized before all involved are in the clear. This is always a dangerous situation, and one that has involved many tree crews.
The updated 1910.269 standard now requires each crew to coordinate with the others and have one person control the clearance, or work independently of each other under individual clearances. The language very closely follows 1910.147, “The control of hazardous energy (lockout/tagout),” which deals with all types of energy, not just the electrical variety. In particular, paragraph 1910.269(m)(iv) closely follows the 1910.147 standard; the specific language can be found in the rules below.
If two or more crews will be working on the same lines or equipment, then:
The crews shall coordinate their activities under paragraph (m) of this section with a single employee in charge of the clearance for all of the crews and follow the requirements of paragraph (m) of this section as if all of the employees formed a single crew, or
Each crew shall independently comply with paragraph (m) of this section and, if there is no system operator in charge of the lines or equipment, shall have separate tags and coordinate deenergizing and reenergizing the lines and equipment with the other crews.
Overhead vs. Underground
When switching overhead, it is much easier to verify that all clearance points are properly opened and tagged because employees can see all the components of the overhead system. Underground distribution (UD) is completely different. With UD, employees are working at remote terminals of connection and isolation points. Every step has to be verified, and each terminal location should be checked for the absence of voltage before next steps are taken. Remember, a marked tag on a cable only means someone wrote something and the marker worked that day.
There are three recent incidents I’m aware of that, as I mentioned at the beginning of this article, were the results of missed steps or improperly written switching orders. In one incident, a substation had been completely isolated with multiple distribution feeder breakers switched out. The load was transferred by closing a normal open gang switch and isolating the feeder just outside the substation by opening switches on a UD riser pole. One was a switch on a UD riser, leaving the substation in plain sight of the substation breaker that should have been opened to prevent feedback from the distribution feeder into the substation. The feeder was energized by backfeed and fed all the way to the top of the breaker in the substation. An employee attempted to attach a system safety ground to the energized risers on the breaker without checking for the absence of voltage. Regardless of what someone says, always follow OSHA regulations. They are the minimum safe work practices.
The second incident was due to a failure to clear capacitors in a substation. This allowed feedback through a closed switch from a capacitor bank to a low-side bus that was supposed to be opened. The step to open and clear the capacitor bank was overlooked when the switching order was both written and reviewed. A failure to check for the absence of voltage before applying system grounds resulted in a flash and contact.
Another substation incident occurred when a station service transformer was not cleared. This is sometimes overlooked in larger switching orders involving substations.
Accuracy is Key
No employee is expected to make mistakes like the ones referenced above, but we are human and therefore fallible. So while there are many checks and balances when writing switching orders to help ensure no steps are left out, it still happens. Fortunately, even in the event of a mistake, if all other regulations are followed and no assumptions are made by any other employees, the mistake likely will be discovered before an incident or injury occurs.
Switching to obtain a clearance happens daily all over the integrated system. Most of these instances are uneventful. However, the recent increase of incidents indicates that mistakes are being made. This article is intended to raise awareness of the importance of safe switching practices and attention to detail.
In summary, the accuracy of the switching order is extremely important. Development, review and execution of the steps should be done with great care. Large and/or complicated switching orders require increased attention to all details of the order.
About the Author: Danny Raines, CUSP, safety consultant, distribution and transmission, retired from Georgia Power after 40 years of service and opened Raines Utility Safety Solutions LLC, providing compliance training, risk assessments and safety observation programs. He is also an affiliate instructor at Georgia Tech Research Center OSHA Outreach in Atlanta. For more information, visit www.electricutilitysafety.com.