Finger safe and Energized electrical work regarding the grounded conductor.

D

daniel fern

Member
I need help finding a resources regarding energized electrical work in regard to a “Finger Safe” disconnect on 415 volt buss duct. Some of the important details are.
The Neutral/ grounded conductor is not part of the 3 Pole “Finger Safe” Disconnect. It is just a lug. The disconnects are installed with the power off then reenergized and loads are connected with the power on. My question is- If the buss duct is fully energized with a load on it, does the neutral become an energized conductor due to imbalances or return path? There is high likelihood for the Neutral to short against ground while cables are being landed and torqued. By incidental touching of torque wrench against enclosure.
 
The ground conductor would generally not be considered an energized conductor.

What is the main concern here (other than the question about if the neutral/ground being energized but not "finger safe")? Is this an issue of management saying that since it is a "finger safe" disconnect that you don't need to treat it as energized work (i.e. less stringent PPE requirements, can go and work in the equipment while energized without doing an Energized Electrical Work Permit, etc.)? Because "finger safe" components have zero impact on whether you can say the work is Energized Work or not.

They merely impact the Electrical Shock Risk Assessment & Arc Flash Risk Assessment that you have to do when doing the Energized Electrical Work Permit. If the equipment to-be-worked-on/in has any energized conductors within it, and you are going within the Restricted Approach Boundary (i.e. inside the electrical cabinet), then an Energized Electrical Work Permit (and accompanying risk assessments) must be done no matter how "finger safe" the components are. This is in accordance with NFPA 70E Article 130.

Also could you please update your profile with location and occupation? It helps with answering your questions.
 
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NOT an energized conductor? You might want to clarify that!
It is true that - with the sole exception of corner-grounded delta systems - you do not put fuses on the grounded conductor. (This is also a good illustration of the difference between a "neutral" and a "grounded conductor"). But you most certainly DO interrupt the grounded conductor in hazardous (classified) locations.
Grounded conductors are almost always carrying some current. Not only is there the situation where multiple circuits share the same "neutral," there are plenty of light switches that let SOME current pass through when in the "off" position. That's the issue behind many LED's and fluorescent lights that can't work with ordinary dimmers.
More importantly, opening a shared grounded conductor will subject the "other" leg to double voltage. It's a good way to let the smoke out.
 
renosteinke said:
NOT an energized conductor? You might want to clarify that!
It is true that - with the sole exception of corner-grounded delta systems - you do not put fuses on the grounded conductor. (This is also a good illustration of the difference between a "neutral" and a "grounded conductor"). But you most certainly DO interrupt the grounded conductor in hazardous (classified) locations.
Grounded conductors are almost always carrying some current. Not only is there the situation where multiple circuits share the same "neutral," there are plenty of light switches that let SOME current pass through when in the "off" position. That's the issue behind many LED's and fluorescent lights that can't work with ordinary dimmers.
More importantly, opening a shared grounded conductor will subject the "other" leg to double voltage. It's a good way to let the smoke out.
Click to expand...
The OP called it both the Ground and Neutral. Hence my assumption that he is simply referring to an EGC (since it is being terminated on an open lug at the disconnect and not on a "finger safe" terminal). He also does not make any mention of this conductor being switched like the 3 phase conductors. He also makes no mention of this being for a classified or hazardous location. So most likely not a switched Neutral. Most likely a feed-thru lug. Which tells me it is an EGC.

But the terminals for the Neutral of a 3-phase wye disconnect would usually also be an unguarded & unswitched lug (I know they make 4-pole disconnects that do, but again it doesn't seem like OP has one of those). But that is on me for assuming (you know what they say about that).

If it is apart of a 3-phase wye system then that would of course make those terminals energized & current carrying conductors (since they are not lugs for the EGC but instead for the neutral conductor).
 
Terminology is important.
The OP says 416V bus, it is likely the source is a grounded wye.
The OP refers to a neutral conductor which might contact ground. It is likely the neutral point of the eye is brought to disconnect switch.

This sounds like a data center where they are making 4wire load side connections to a denergized(?) switch. In general a neutral lug is not considered an energized conductor, relative to ground, until the load has been added. Without a load there is not a complete current path.

If you do not make assumptions you cannot move forward in problem solving. For example I assume my readers know what 416V bus in a data center is.
 
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