Replacing a breaker in a 480v 3phase panel that is part of a distribution cabinet. It is also a wireway for DLO cables that pass through the lower portion of cabinet to an adjacent meter section. The panel will be de-energized according to MOP. The DLO cables will continue to be energized during the replacement of breaker. The DLO cables do not have to be manipulated in any manner in order to replace the breaker. Does NFPA 70e still consider this working in an electrically energized situation? Please give reference.
Exposed Electrical Work
- Thread starter RedSafety
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The applicable section is 130.2 and defines two conditions for needing to establish an electrically safe work condition for systems above 50 V:
1. Working within limited approach boundary. Only applies to exposed electrical parts, so the pass-through conductors are excluded.
2. Interacting with equipment where conductors or circuit parts are not exposed but an increased likelihood of arc flash hazard exists. Since the conductors pass through the enclosure and are not being manipulated, the risk of arc flash is minimal.
1. Working within limited approach boundary. Only applies to exposed electrical parts, so the pass-through conductors are excluded.
2. Interacting with equipment where conductors or circuit parts are not exposed but an increased likelihood of arc flash hazard exists. Since the conductors pass through the enclosure and are not being manipulated, the risk of arc flash is minimal.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
what happens if he drops a tool on the DLO conductors while removing the breaker?
I said minimal, not nonexistent. Ultimately it's up to them to define their risk tolerance.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
I imagine it would have to be a very sharp tool... DLO insulation is fairly tough stuff.
alexfox1986
Member
- Location
- Manchester
- Occupation
- Electrical Engineer
Hi! According to NFPA 70E (2021 edition), even if the panel is de-energized, if there are energized conductors or circuit parts in the vicinity of the work being performed, it is still considered electrical work on or near exposed energized conductors or circuit parts, and the appropriate electrical safety practices and personal protective equipment (PPE) must be used.
Specifically, NFPA 70E defines an "energized electrical conductive work" as "work on or directly associated with exposed energized electrical conductors or circuit parts that are not in an electrically safe work condition." An "electrically safe work condition" is defined as "a state in which an electrical conductor or circuit part has been disconnected from energized parts, locked/tagged in accordance with established standards, tested to ensure the absence of voltage, and grounded if determined necessary."
Therefore, in your situation, even though the panel is de-energized, the DLO cables passing through the wireway are still energized, and the work being performed on the panel is considered work on or near exposed energized conductors or circuit parts. You should follow the appropriate electrical safety practices, including wearing the required PPE and following the established lockout/tagout procedures, to protect yourself from potential electrical hazards.
Reference: NFPA 70E (2021), Standard for Electrical Safety in the Workplace, Article 100 Definitions, Article 130 Work Involving Electrical Hazards, and Article 120 Establishing an Electrically Safe Work Condition.
- Location
- Bremerton, Washington
And thats very good advice. We often see a question and then no reply from the OP
alexfox1986
Member
- Location
- Manchester
- Occupation
- Electrical Engineer
Thank you for the advice!
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I thought the board software was set to close out old threads.
You're welcome.
It is but it's a year if there has been no activity.
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