Also if you have multiple VFD's in one cabinet and you are changing one but the rest are powered up would a wok permit be required?
Good morning Kristopher, It seems that you may have two different situations that you are asking about. As to your first question, NFPA 70E (2018) 130.2(B)(2) would apply. In most MCC buckets that I have had the experience of working on the line side to the breaker or disconnect is guarded and there are no exposed energized conductors or circuit parts but that there would be an increased likelihood of exposure to an arc flash hazard.
In reference to your second question, if there are exposed energized conductors or circuit parts within the restricted approach boundary then an energized electrical work permit would be required. In motor control enclosure that contain multiple VFD's or other motor control equipment one of the potential hazards is "look-alike equipment".
I hope that this is helpful to you.
The question and Answer:
1. Is the worker exposed to live (energized) parts? Example troubleshooting power to bucket. If exposed, a permit is required unless the procedure has already been deemed routine.
2. Is this a routine application the worker has already been given authority to work on energized? If yes, no permit required
3. Are barriers or is a curtain available that prohibits the worker from being exposed once the door is open?
Hope this helps
Please provide references to what is deemed routine.
A critical piece of information missing from the discussion is identifying the scope of the work. This is where a lot of us get confused and can become an area of contention. As Steve pointed out, work that is performed within the restricted approach boundary (for shock hazards) requires a permit, or work performed where there is an increased likelihood of exposure to an arc flash hazard, UNLESS that work falls under the categories that are exempted from the permit requirement, such as
Testing, Troubleshooting, or Voltage Measurements
Thermography, ultrasound, or visual examination if the restricted approach boundary is not crossed
Access and Egress to or from an area, if no electrical work is performed and the restricted approach boundary is not crossed
General Housekeeping or non-electrical tasks where the restricted approach boundary is not crossed
Let's look at each of those a bit closer
Testing and Troubleshooting always give us a problem because these are terms that can be difficult to define, and many organizations have different ideas about what “testing” or “troubleshooting” allow, but generally (at least in my opinion and experience) neither of these tasks should involve a physical change to the electrical conductor arrangement or circuit part configuration. Voltage Measuring is a bit easier to define, and we can usually all agree that this is touching an exposed conductor or circuit part with a meter, but it is important to point out that it is these activities that often result in the most common accidental contact accidents in the industry. Particularly voltage measuring with the wrong meter can result in catastrophic equipment failures and arc flash exposure. Be sure you define this scope of work before you begin, but if you can agree that the work you are doing is in this category you can take the exemption from a required permit.
Thermography, ultrasound, or visual examination, but wait – it says specifically only if the restricted approach boundary is not crossed. Okay, but, “I thought if the restricted approach boundary isn’t crossed no permit is required in the first place.” I hear this a lot, and this is where knowing your terms and boundaries is critical. Obviously if the restricted approach boundary isn’t going to be crossed the work does not require a permit, FOR SHOCK RISK assessment purpose, so this clearly is in reference to that permit required instance when you have identified an arc flash risk. Exposed conductors or circuit parts that pose an arc flash hazard, from your risk assessment, require a permit, UNLESS you can say the scope of work is only Thermography, Ultrasound, or Visual Examinations.
Access to and Egress from, as well as General Housekeeping, are new to the exemption from a permit discussion and try to address those tasks we haven’t looked at in the past because we are generally focused on the electrical work, while it is clear that in many industries, qualified workers who are not performing electrical tasks may need to be escorted past a limited approach boundary to do the work they are responsible for, and we want to give the employer the ability to address that work, address and control the risks and hazard, without the requirement of a permit. From the brief discussion at the start here it is likely that this is not the scope of work that is of concern.
So, in conclusion, define your scope – if your scope cannot fit the limited types of work where an exemption is allowed, and you are clearly within the requirement of a permit from the risk assessments you have performed, you should be doing a permit. But, like I have said before, you should never be afraid of doing a permit, or concerned that doing a permit is somehow putting you in a “bad” or “wrong” place. The energized electrical work permit is another tool in your kit to help you address risks, control hazards, and help create a safe work condition, as safe as you can hope to achieve, for work activities that require exposure to electrical hazards.
Thank you all for the help
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