Tyndale's NFPA 70E Made Easy:
120.6 – Process for Establishing and Verifying an Electrically Safe Work Condition
This section of NFPA 70E Made Easy covers 120.6 - Process for Establishing an Electrically Safe Work Condition (ESWC). There are 8 total steps within Section 120.6, which we cover in-depth below.
Note: The checklist provided by the 70E is a minimum standard. You must establish your own electrical safety program and procedures to de-energize equipment at your specific job site location, which could require more processes than mentioned below to ensure safety. Establishing an ESWC involves energized work; ensure full understanding of all energized work policies and procedures.
Step 1
Determine all possible sources of electrical supply to the specific equipment. Check applicable up-to-date drawings, diagrams, and identification tags.
A single piece of equipment, such as a transfer switch or motor control center (MCC) can have multiple power sources. You can’t just turn off one power source and begin working. To Use provided documentation (like one-lines, panel schedules, schematics, blueprints, or incident energy stickers) to ensure complete de-energization before beginning work.
Step 2
After properly interrupting the load current, open the disconnecting device(s) for each source.
To help visualize this process, let’s use an MCC as an example. You shouldn’t turn off the main breaker on an MCC without turning off the individual loads. Instead, you could follow this process:
- Turn off the individual branch loads
- Disable the main breaker
- Perform your work
- Restore power by turning the main breaker back on
- Gradually bring the equipment back online
Avoid operating a main switch under load – even if it's load rated –to minimize risk of damage to the switch contacts or risk of an arc flash.
Step 3
Wherever possible, visually verify that all the blades of the disconnecting device are fully open, or that drawout-type circuit breakers are withdrawn to the “test” or fully disconnected position.
This step is crucial. For instance, if you shut off a disconnect without visual confirmation that it’s off, lock it out, and proceed downstream to work, you risk serious injury or death. Additionally, opening a disconnect and visually confirming may require personal protective equipment (PPE) for arc flashes and shocks. If you can’t visually verify, then you must follow through with all your testing procedures.
Step 4
Release stored electrical energy.
You can release the stored electrical energy in the form of batteries, capacitors, or even inductance. Some equipment could take time before it’s safe to work on. Variable frequency drives and speed drives are good examples – if there’s not an electrical drain, you could be shocked by the capacitors on that equipment.
Step 5
Block or relieve stored nonelectrical energy in the devices to the extent that the circuit parts cannot be unintentionally energized by such devices.
There are several non-electrical energy sources, such as pneumatics and hydraulics. These systems often include a breaker that has been charged, but hasn’t been activated by pressing the ‘closed’ or ‘on’ button. This means mechanical energy is present, which could energize the breaker and must be blocked or released. Another example is a pressure switch that can close after a certain amount of air has leaked out.
Step 6
Apply lockout/tagout devices in accordance with a documented and established procedure.
Pay close attention to the phrase “documented and established procedure.” This means that it is your responsibility to develop and implement the lockout/tagout program at your facility. Learning a lockout/tagout procedure properly through an instructional video or online can be very challenging, if not impossible. The best approach is to visit your job site and create a program tailored to the specific equipment and the steps needed.
Step 7
Use an adequately rated portable test instrument to test each phase conductor or circuit part at each point of work to test for the absence of voltage.
You need to test each phase conductor or circuit part, both phase-to-phase and phase-to-ground, before and after each test. Ensure that the test instrument is operating correctly by verifying it on a known voltage source. This means that you must check A to B, B to C, A to C, A to ground, B to ground, C to ground – any combination that could have voltage present. You must also perform a “Live Dead Live” test before and after each test.
To summarize, this involves three steps:
- Verify your test instrument on a known voltage source.
- Test the specific area where you will be working.
- Recheck your instrument to ensure it is working properly.
You can verify your instrument using a wall outlet, a meter proving station, or any other approprite power source. You're allowed to use a permanently installed absence of voltage (AOV) meter at your specific work location, as long as a few rules are followed:
- The absence of voltage detector meter is permanently mounted and installed per the manufacturer’s instruction, and it tests all the terminals at the location where you’re working.
- The meter is listed and labeled for testing for absence of voltage.
- The meter tests all combinations of phases to ground.
- The meter self-tests before and after each AOV testing to verify correct operation of the unit.
It's important to note that when meeting or exceeding 1000 volts, it’s okay to use an approved non-contact testing device. However, direct contact is encouraged for lower voltages.
Note: The term “adequately rated meter” is frequently misunderstood.
Step 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: placement, capacity, and impedance.
We cover placement, capacity, and impedance in a future video about Section 120.6 8A. This step involves grounding the system for protection from induced voltages, lightning, and similar hazards, which is typically handled with a grounding cluster. However, grounding clusters do not apply to most workers who work at lower voltages, like 120V to 480V.
Bottom Line
According to the ESWC Policy, you must de-energize equipment whenever possible. That means following steps 1-8 of 70E Section 120.6, which includes physically removing any hazards by de-energizing them before beginning work. Keep in mind that additional processes might be necessary to ensure safety at your specific location. Therefore, you must establish your own electrical safety program and procedures to de-energize equipment.
Tyndale’s "NFPA 70E Made Easy" video series – hosted by Jason Brozen, Tyndale’s Lead Corporate Safety and Technical Trainer, a 28-year Master Electrician and an NFPA Certified Electrical Safety Compliance Professional (CESCP) – makes electrical safety accessible and understandable for all. The series delves into the intricacies of NFPA 70E, a vital tool since 1979 for establishing practical and safe workplaces. Recognizing its significance, we’ve created an entire educational resource hub dedicated to this essential standard, offering comprehensive insights and guidance.
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