The Lights are Out: Now What?
For the electrical worker in the field, this is all too common – a significant medium-voltage electrical fault event occurs, production lines are down, people are standing around, and management needs the facility back up and running as soon as possible. Time. Is. Money.
For a qualified electrical worker, especially when it involves medium-voltage equipment and systems, many aspects of NFPA 70E immediately kick into action. This article intends to highlight a few real-life 70E scenarios for the worker in the field….
Applying NFPA 70E to a Medium-Voltage Fault Event
Scene No. 1
What’s the Risk?
What’s the first thing you do – make sure it’s de-energized? Or is it more than that?
The answer can be found in [Key Point] Article 110 General Requirements for Electrical Safety-Related Work Practices. You need to assess the risk before any work begins.
The substation is dark, the sun is coming up, and the smoke is just starting to clear. There is general chaos around the substation: damaged equipment, loss of power, emergency systems are running, effects from the outage are felt throughout the plant, and members of upper management are starting to arrive to “lend a hand”….and you have just got to the scene as the person in charge of the remediation. Remain calm. Assess the risk. Map out the plan and recovery strategy in your mind and apply the rules and requirements of the 70E in your thought streams.
Key Point: Article 110.1 Priority.
Hazard elimination shall be the first priority in the implementation of safety-related work practices.
The 70E is very clear on this point – it’s at the front of the standard, and the intent is for you to plan all of your tasks and protect all of the employees working on or near the electrical equipment. OSHA 29 CFR 1910.333(a)(1) states, “Live parts must be de-energized before the employee works on or near them.”
To assess the risk, you need to apply several principles of safe work practices before you begin, principles such as:
1. Identifying the hazards and minimizing the risks
2. Establishing an electrically safe work condition
3. Protecting employees, both workers on the project and other bystanders
4. Planning all the tasks to be performed
5. Anticipating unexpected events and have a plan to deal with them
6. Ensuring the qualifications and abilities of anyone working on the project
7. Determine the condition of maintenance of electrical equipment
8. Using correct tools and appropriately rated portable meters
It’s clear that a risk assessment must be performed before troubleshooting and repairs begin.
Key Point: Article 110.5(H)(1) Elements of a Risk Assessment Procedure.
The risk assessment procedure shall address employee exposure to electrical hazards and shall identify the process to be used before work is started to carry out the following:
(1) Identify hazards
(2) Assess risks
(3) Implement risk control according to the hierarchy of risk control methods
So if you follow 110.5(H)(1), you should: identify the hazards, analyze the risk, and also evaluate the risk.
Remember, risk is not only the likelihood that an incident might occur, but also the possible severity of injury or [further] damage to equipment that could be a result of an incident. So the risk might have a high probability of occurrence, but the result could be a minor injury… or conversely… it might have a low likelihood of occurrence but present a possibility of severe injury. You have to consider what your scenario will likely bring about.
For example, are there high levels of risk, including both shock and arc flash hazards? Or does shock hazard create the greatest risk, with a minimal risk from incident energy exposure?
Key Point: NFPA 70E Annex F “Risk Assessment and Risk Control.” For further information and guidance on risk assessment, please refer to Annex F in the 70E.
Scene No. 2
Energized, De-Energized, or Electrically Safe?
We know power is out to the substation; after all, the rodent caused a large arc flash and fault event, and everything is shut down. The alarms tell us that, the noise – or lack of noise, tells us that, and the burned rat lying in the substation tells us that. And upper management has already reminded us several times and asked, “The power is out, and what are you going to do about it?”
But de-energization itself does not create an electrically safe work condition, and just because something is “de-energized”, it does not describe a safe condition. Also, remember those emergency alarms and annoying sirens – where is that power coming from?
What you must do, before any work begins, is establish an electrically safe work condition (ESWC).
The main premise for providing employees with an electrically safe work environment is to place electrical equipment in an electrically safe work condition, unless it is being used under normal operation.
So any time a piece of equipment has been deenergized, and electrical service or maintenance work is to be performed, Key Point: Article 120.5 Process for Establishing and Verifying an Electrically Safe Work Condition. This article in the 70E has a very specific process to establish the ESWC, which states:
Establishing and verifying an electrically safe work condition shall include all of the following1 steps, which shall be performed in the order presented1, if feasible:
(1) Determine all possible sources of electrical supply to the specific equipment. Check applicable up-to-date drawings, diagrams, and identification tags.
(2) After properly interrupting the load current, open the disconnecting device(s) for each source.
(3) Wherever possible, visually verify that all blades of the disconnecting devices are fully open or that drawout-type circuit breakers are withdrawn to the test or fully disconnected position.
(4) Release stored electrical energy.
(5) Block or relieve stored non-electrical energy in devices to the extent that the circuit parts cannot be unintentionally energized by such devices.
(6) Apply lockout/tagout devices in accordance with a documented and established procedure.
(7) Use an adequately rated portable test instrument to test each phase conductor or circuit part to test for the absence of voltage. Test each phase conductor or circuit part both phase-to-phase and phase-to-ground. Before and after each test, determine that the test instrument is operating satisfactorily through verification on any known voltage source.
(8) Where the possibility of induced voltages or stored electrical energy exists, ground all circuit conductors and circuit parts before touching them. Where it could be reasonably anticipated that the conductors or circuit parts being de-energized could contact other exposed energized conductors or circuit parts, apply temporary protective grounding equipment in accordance with the following:
a. Placement. Temporary protective grounding equipment shall be placed at such locations and arranged in such a manner as to prevent each employee from being exposed to a shock hazard (i.e., hazardous differences in electrical potential). The location, sizing, and application of temporary protective grounding equipment shall be identified as part of the employer’s job planning.
b. Capacity. Temporary protective grounding equipment shall be capable of conducting the maximum fault current that could flow at the point of grounding for the time necessary to clear the fault.
Note1 emphasis added.
As you can see from the information above, the 70E provides a great resource for the process of establishing an ESWC. Use it in the execution of your strategy to prepare the worksite for the remediation efforts on the 15 kV switchgear.
We have now completed two of the eight steps we had originally mapped out in our emergency project by specifically following guidance presented to us in NFPA 70E. Those original steps were:
1. Identifying the hazards and minimizing the risks (done)
2. Establishing an electrically safe work condition (done)
3. Protecting employees, both workers on the project and other bystanders
4. Planning all the tasks to be performed
5. Anticipating unexpected events and have a plan to deal with them
6. Ensuring the qualifications and abilities of anyone working on the project
7. Determine the condition of maintenance of electrical equipment
8. Using correct tools and appropriately rated portable meters
Stay tuned for future editions of NETA World as we go through the balance of these steps to get the facility back up and running.
As for the culprit in all of this, Mickey the mouse? He, unfortunately, is not doing too well. Electricity is a dangerous thing, man.
Stay safe out there, turn it off, and Test Before Touch!