What does the NEC & OSHA have to say about PPE when working on energized equipment?

Tommy1776

Member
Location
SC
Occupation
Electrician
Greetings Brother

What does NEC & OSHA have to say about what PPE is required when working on energized equipment.

Let's say a thermal scan was performed on a 480-volt breaker and one leg was showing very hot.
You have been tasked with tightening a terminal lug on the center phase of a 3 phase live breaker.

What PPE is required before opening the breaker door and breaking the plane of protection.
What NEC or OSHA PPE requirements are needed for the qualified electrician to perform work on an energized circuit?

OSHA
1910.333(a)(1)
1910.335(a)(2)(i)
1910.331(a)
1910.334(c)(1)
 

tom baker

First Chief Moderator
Staff member
The NEC is an installation standard, and does not cover this. NFPA 70E is the gold standard for electrical safety, it requires PPE appropriate for the task. My state is not under OSHA and does not use 70E, but I believe OSHA references 70E
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
You have been tasked with tightening a terminal lug on the center phase of a 3 phase live breaker.
And not remove the lug to inspect for damage? I see this 'task' as a big fail. Will the PPE be enough to protect the worker when the lug breaks off while being tightened? Plus, it's only a guess that a loose lug is causing the heat. 'Tightening' could result in over tightening. Fail #2.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I would bet that the tightening of the lug would not be permissible energized work. Such work is VERY rare, even though it is often done.
(NFPA 70E)110.3 Electrically Safe Work Condition.
Energized electrical conductors and circuit parts operating at voltages equal to or greater than 50 volts shall be put into an electrically safe work condition before an employee performs work if any of the following conditions exist:
(1) The employee is within the limited approach boundary.
(2) The employee interacts with equipment where conductors or circuit parts are not exposed but an increased likelihood of injury from an exposure to an arc flash hazard exists.

(NFPA 70E) 110.4 Energized Work.
(A) Additional Hazards or Increased Risk.
Energized work shall be permitted where the employer can demonstrate that de-energizing introduces additional hazards or increased risk.
(B) Infeasibility.
Energized work shall be permitted where the employer can demonstrate that the task to be performed is infeasible in a de-energized state due to equipment design or operational limitations.


Remember, if the facility cannot tolerate a planed outage to make this repair, how will they be able to tolerate an unplanned one if something goes wrong while attempting to make the repair on energized equipment?

In addition, tightening is not the correct fix. The lug itself and the lug connection to the bus must be looked at. One or both of those items may require replacement. If those are both ok, which is not very likely, the conductor needs to have the end cut off, insulation stripped and re-terminated in the existing or new lug.
 
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Josh111

Senior Member
Location
USA
As others have stated the NEC doesn’t regulate PPE or when energized work is allowed. OSHA does, and NFPA70E can be a good guideline to achieve compliance. I hope this is truly a hypothetical and not something someone is considering doing. And tightening a lug on a breaker while under the road is quite dangerous. I think it’s likely that you don’t know based on the scan alone whether or not the lug is stripped out or something else and you might find out by surprise in a manner that could at best result in you still having to shut the system down to fix it and at worst result in some type of serious incident occurring while you manipulate it. Even if you have PPE for this, you run the risk of causing catastrophic damage to the gear if there’s an incident.

As for the rules though, you have to demonstrate that de-energizing the gear would create a greater hazard, or that due to testing its infeasible. Then after that you can resort to the energized work, so long as all precautions including PPE and other safe work practices are employed and are effective at mitigating the hazard. It’s unlikely that you can clear any of these thresholds, based on what’s given here.

You might want to note that even for opening up the gear to do a thermal scan under load, you should be wearing proper PPE. That is, unless somehow you are able to do your scan from outside of the arc flash hazard boundary after someone else with proper PPE opens it up.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
As others have said, hidden defects can be catastrophic. I denied a live work permit to one of my guys replacing a snap in breaker. He called me back later and thanked me for denying the permit. When he shut it off, and pulled the old breaker out, part of the buss came with it. Definitely would have caused an arc flash!
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
Let's say a thermal scan was performed on a 480-volt breaker and one leg was showing very hot.
You have been tasked with tightening a terminal lug on the center phase of a 3 phase live breaker.

What PPE is required before opening the breaker door and breaking the plane of protection.
Then it should be de-energized, removed, inspected, cleaned, and re-torqued to proper specifications..
Just tightening a terminal lug isn’t the proper way to fix a hot spot.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
Everyone voted for de-energize interesting.
Lets modify the OP's scenario with some specifics; your going to work a 800A 480V MLO panelboard and its a 1980's era service with 6 mains, no arc flash labeling. The only way to de-energize is to call the local POCO.

Say your going to install a custom knockout for a new 2 inch conduit, replace a breaker or add grounding electrode bond to the neutral or something smaller, like installing a ko seal.

You can see three 25kVA pole pigs outside, so you have some idea of the transformer size.


No go back to his question:
What PPE is required before opening the breaker door and breaking the plane of protection.
What do you all typically wear? Or do you still just de-energize?
 

kwired

Electron manager
Location
NE Nebraska
Everyone voted for de-energize interesting.
Lets modify the OP's scenario with some specifics; your going to work a 800A 480V MLO panelboard and its a 1980's era service with 6 mains, no arc flash labeling. The only way to de-energize is to call the local POCO.

Say your going to install a custom knockout for a new 2 inch conduit, replace a breaker or add grounding electrode bond to the neutral or something smaller, like installing a ko seal.

You can see three 25kVA pole pigs outside, so you have some idea of the transformer size.


No go back to his question:

What do you all typically wear? Or do you still just de-energize?
Throw another wrench into the gears and lets say it is a corner grounded system but it is clear to you that over the years those that worked on it didn't understand there is a difference between grounded and grounding conductors?

Regardless you are supposed to wear appropriate PPE even if only to verify there is no voltage when you decided it would be best to deenergize to perform your main task.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Everyone voted for de-energize interesting.
Lets modify the OP's scenario with some specifics; your going to work a 800A 480V MLO panelboard and its a 1980's era service with 6 mains, no arc flash labeling. The only way to de-energize is to call the local POCO.

Say your going to install a custom knockout for a new 2 inch conduit, replace a breaker or add grounding electrode bond to the neutral or something smaller, like installing a ko seal.

You can see three 25kVA pole pigs outside, so you have some idea of the transformer size.


No go back to his question:

What do you all typically wear? Or do you still just de-energize?
Yes, I am going to get the power company to de-energize the service and if the customer doesn't like that, he can find some other contractor willing to risk his company and employees.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
Yes, I am going to get the power company to de-energize the service and if the customer doesn't like that, he can find some other contractor willing to risk his company and employees.
A wise man once said, "Remember, if the facility cannot tolerate a planed outage to make this repair, how will they be able to tolerate an unplanned one if something goes wrong while attempting to make the repair on energized equipment?" ;)
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
Thanks all for the clarification. 480V 800A MLO services are pretty common around here.

Last year one of our guys was in a similar situation, and I called a few outfits to see if they could make a proper arc flash study (no calls back), so I backed up his opinion to de energize.
We got some push back, but it was agreed and we called the POCO to de-energize, set up everything for a few weeks out.
When our crew got there the following day the 'plant electrician' had installed the knockout already.
I tried to chat with the managers but got the 'ok bye and close the door on your way out' vibe.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Thanks all for the clarification. 480V 800A MLO services are pretty common around here.

Last year one of our guys was in a similar situation, and I called a few outfits to see if they could make a proper arc flash study (no calls back), so I backed up his opinion to de energize.
We got some push back, but it was agreed and we called the POCO to de-energize, set up everything for a few weeks out.
When our crew got there the following day the 'plant electrician' had installed the knockout already.
I tried to chat with the managers but got the 'ok bye and close the door on your way out' vibe.
This type of issue is the reason behind the requirements in 230.71(B) for the 2020 code. That places the service disconnect in a separate compartment or enclosure.
 

Tommy1776

Member
Location
SC
Occupation
Electrician
Greetings Brothers

Thank you for the responses.

What is the proper PPE for working on energized electrical equipment?

Let's say a thermal scan was performed on a large air handler disconnect 480-volt breaker and one leg was showing very hot on the center Phase.


You have been tasked with tightening a terminal lug on the center phase of a 3 phase live breaker.


What are the NFPA or OSHA {PPE requirements} for the qualified electrician to perform safe electrical work on an energized circuit?

OSHA 29 CFR Part 1910 Occupational Safety and Health Standards

NFPA 70E 110.3 Standard for Electrical Safety in the Workplace
NFPA 70E 110.4 Energized Work.

Tommy
 
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Josh111

Senior Member
Location
USA
Greetings Brothers

Thank you for the responses.

What is the proper PPE for working on energized electrical equipment?

Let's say a thermal scan was performed on a 480-volt breaker and one leg was showing very hot on the center Phase.


You have been tasked with tightening a terminal lug on the center phase of a 3 phase live breaker.


What are the NFPA or OSHA {PPE requirements} for the qualified electrician to perform safe electrical work on an energized circuit?

OSHA 29 CFR Part 1910 Occupational Safety and Health Standards

NFPA 70E 110.3 Standard for Electrical Safety in the Workplace
NFPA 70E 110.4 Energized Work.

Tommy
All the responses here are relevant. Sometimes it takes real courage to approach your boss, customer, etc and say that you are sorry but you can not do this. From what most of us can tell of the scenario you have described here, the OSHA and NFPA 70E rules would be to not do this. So there's not really any good suggestions on how to do it in accordance with OSHA/NFPA rules.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Greetings Brothers

Thank you for the responses.

What is the proper PPE for working on energized electrical equipment?

Let's say a thermal scan was performed on a 480-volt breaker and one leg was showing very hot on the center Phase.


You have been tasked with tightening a terminal lug on the center phase of a 3 phase live breaker.


What are the NFPA or OSHA {PPE requirements} for the qualified electrician to perform safe electrical work on an energized circuit?

OSHA 29 CFR Part 1910 Occupational Safety and Health Standards

NFPA 70E 110.3 Standard for Electrical Safety in the Workplace
NFPA 70E 110.4 Energized Work.


Tommy
The references you list tell you that in almost all cases repairing that lug while the equipment is energized is not permitted.

Again tightening the lug is not the answer.

The equipment needs to be shut down and the lug examined to determine if it can still be used, and the connection between the terminal and the bus needs to be examined to make sure there has been no damage to the bus itself.
If the lug and bus are in good condition, you can re-terminate the conductor after cutting off the portion of the conductor that was previously in the lug and making a completely new termination. Note that it is not likely that a lug that shows excessive heat will be suitable for reuse.
 

kwired

Electron manager
Location
NE Nebraska
Thanks all for the clarification. 480V 800A MLO services are pretty common around here.

Last year one of our guys was in a similar situation, and I called a few outfits to see if they could make a proper arc flash study (no calls back), so I backed up his opinion to de energize.
We got some push back, but it was agreed and we called the POCO to de-energize, set up everything for a few weeks out.
When our crew got there the following day the 'plant electrician' had installed the knockout already.
I tried to chat with the managers but got the 'ok bye and close the door on your way out' vibe.
Did POCO shut them off at the time planned for anyway?
 

pv_n00b

Senior Member
Location
CA, USA
Everyone voted for de-energize interesting.
Lets modify the OP's scenario with some specifics; your going to work a 800A 480V MLO panelboard and its a 1980's era service with 6 mains, no arc flash labeling. The only way to de-energize is to call the local POCO.

Say your going to install a custom knockout for a new 2 inch conduit, replace a breaker or add grounding electrode bond to the neutral or something smaller, like installing a ko seal.

You can see three 25kVA pole pigs outside, so you have some idea of the transformer size.


No go back to his question:

What do you all typically wear? Or do you still just de-energize?
I do a lot of power studies on commercial service entrance equipment and in almost all cases there is no safe PPE to work on anything that exposes the worker to an arc flash on the utility side. Even working on the load side of the main breaker still exposes the worker to the line side and a possible arc flash from that area. So do the utility shutdown. It's a pain but it's the only safe way to do it.
 

mayanees

Senior Member
Location
Westminster, MD
Occupation
Electrical Engineer and Master Electrician
Greetings Brothers

Thank you for the responses.

What is the proper PPE for working on energized electrical equipment?

Let's say a thermal scan was performed on a large air handler disconnect 480-volt breaker and one leg was showing very hot on the center Phase.


You have been tasked with tightening a terminal lug on the center phase of a 3 phase live breaker.


What are the NFPA or OSHA {PPE requirements} for the qualified electrician to perform safe electrical work on an energized circuit?

OSHA 29 CFR Part 1910 Occupational Safety and Health Standards

NFPA 70E 110.3 Standard for Electrical Safety in the Workplace
NFPA 70E 110.4 Energized Work.

Tommy
If this is a case where it is truly more dangerous to turn power off then the process would be:
1) Fill out an EEWP which is located in 70E, Annex J. Filling out this form necessitates Shock Risk and Arc Flash Risk Assessments where the appropriate PPE will be determined. The form also spreads the responsibility of doing energized work to a whole group of people by requiring signatures.
2) Wear PPE as determined by the EEWP and make the adjustment using insulated tools. The restricted approach boundary will be crossed with the tool, but an extension could be used to minimize the arc flash incident energy exposure.

The EEWP would also review the job for better a determination of success associated with just tightening the lug.

In my opinion, if the lug is loose this is an easy fix. It's something I wouldn't have thought twice about 30 years ago but the way 70E is written this type of work can only be justified with an EEWP. The main thing is to make an accurate determination of the appropriate PPE, and in my opinion that's by using the Incident Energy calculations and not the PPE Categories method.
 

jap

Senior Member
If this is a case where it is truly more dangerous to turn power off then the process would be:
1) Fill out an EEWP which is located in 70E, Annex J. Filling out this form necessitates Shock Risk and Arc Flash Risk Assessments where the appropriate PPE will be determined. The form also spreads the responsibility of doing energized work to a whole group of people by requiring signatures.
2) Wear PPE as determined by the EEWP and make the adjustment using insulated tools. The restricted approach boundary will be crossed with the tool, but an extension could be used to minimize the arc flash incident energy exposure.

The EEWP would also review the job for better a determination of success associated with just tightening the lug.

In my opinion, if the lug is loose this is an easy fix. It's something I wouldn't have thought twice about 30 years ago but the way 70E is written this type of work can only be justified with an EEWP. The main thing is to make an accurate determination of the appropriate PPE, and in my opinion that's by using the Incident Energy calculations and not the PPE Categories method.

Yes, and, after the whole group has signed the form that spreads the responsibility of doing work on energized equipment, say a short prayer that you are not the one person in the group that they hand the torque wrench to.


JAP>
 
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