Electric Panel & Disconnect Switch-Arc Flash PPE
Electric Panel & Disconnect Switch-Arc Flash PPE
(OP)
Hi All,
I did some research on this site looking some basic answers but could not get to the bottom of my dilemma.
In case of a 600V/480 V fused disconnect switch or an electric panel(240 V fed from 150 kVA TXF), if we have to just operate these equipment while these are encased and similar goes to a 600 V switchgear, Is it mandatory by NEC, CSA Z462, NFPA or recommended to wear proper PPE while operating this equipment.
I am sure a lot you guys look in to the electrical safety program in your facilities everyday. I am in consulting buisness and dont get to see a site everyday.
For example, a lighting panel in a office hallway, if it has a cat 3 energy, Is it ok for some body to operate it without a PPE may be for a Janitor.
I would appreciate an opinion.
Thanks
I did some research on this site looking some basic answers but could not get to the bottom of my dilemma.
In case of a 600V/480 V fused disconnect switch or an electric panel(240 V fed from 150 kVA TXF), if we have to just operate these equipment while these are encased and similar goes to a 600 V switchgear, Is it mandatory by NEC, CSA Z462, NFPA or recommended to wear proper PPE while operating this equipment.
I am sure a lot you guys look in to the electrical safety program in your facilities everyday. I am in consulting buisness and dont get to see a site everyday.
For example, a lighting panel in a office hallway, if it has a cat 3 energy, Is it ok for some body to operate it without a PPE may be for a Janitor.
I would appreciate an opinion.
Thanks






RE: Electric Panel & Disconnect Switch-Arc Flash PPE
It sounds like you (they) are using the tables, an actual Ei from an analysis may show a much lower hazard.
RE: Electric Panel & Disconnect Switch-Arc Flash PPE
It has a Cat3 .energy level. The suggestion is to install a current limiting fuse disconnect switch in parallel with the existing switch. So when a repair needs to be done
on the switchgear, the fused switch will be closed and the non-fused switch will be opened. So that while repair is being done the arc energy is less due to the fused switch.
What I am wondering is that; some body who will operate that non fused switch , Does he need to wear a PPE because that switch has a cat 3 arc level as well. If yes than there is no point in having this fused switch?
I would appreciate a word.
Thanks
RE: Electric Panel & Disconnect Switch-Arc Flash PPE
Chances are there are better solutions. But to answer your question, the same hazard would exist for operating the fused and non-fused switch because it is the fault current coming to the switch and the clearing time of the upstream breaker that determne the hazard level.
RE: Electric Panel & Disconnect Switch-Arc Flash PPE
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RE: Electric Panel & Disconnect Switch-Arc Flash PPE
RE: Electric Panel & Disconnect Switch-Arc Flash PPE
But if you are using the Table in NFPA 70E in lieu of doing a study, then there is a difference because the table is task-based, rather than hazard-based.
This is big inconsistency in NFPA 70E that creates a lot of confusion.
We all feel safer with the doors closed or covers on, and instinctively we know it is safer, but it is always good to remember that there is no testing done to determine how much safer. If there is enough incident energy released, the doors and covers can be blown off, unless the gear is arc-rated as Zog says.
We generally revert to the NFPA table for 120/240 V panels just because there is no other approach that makes any sense.
"The more the universe seems comprehensible, the more it also seems pointless." -- Steven Weinberg
RE: Electric Panel & Disconnect Switch-Arc Flash PPE
RE: Electric Panel & Disconnect Switch-Arc Flash PPE
So that means installing a fused switch in parallel with the non fused switch is ok and when ever a repair needs to be done on switchgear with doors open, the fused switch will be closed and non fused switch will be open.
Based on the current Arc flash analysis, I put a bus to simulate the energy level at the switch, the energy level is 3, So I should presume that it should not matter because all these switches have doors and can be operated without worrying about being blown off?
If arc flash is not a concern with doors closed, why we need remote racking device for breakers.
Iwould appreciate a word.
RE: Electric Panel & Disconnect Switch-Arc Flash PPE
I think you are mis-reading the comments made.
I'd suggest maybe hiring someone qualified to do an arc-flash hazard analysis.
"The more the universe seems comprehensible, the more it also seems pointless." -- Steven Weinberg
RE: Electric Panel & Disconnect Switch-Arc Flash PPE
First and foremost, you cant work on switchgear energized unless you have a justifiable reason to do the work energized.
Second, to operate the switches you are discussing (Fused or unfused) there is an arc flash hazard and you will need PPE.
Third, "energy level 3" makes no sense at all, you dont seem to be grasping the doors open/closed concept, the doors dont protect you, at least you have to assume they wont.
TPlease follow dpc's advice and hire a qualified engineering firm to do your analysis for you, or get the right training. We are glad to help but cant do it all for you.