Code section for arc flash label

B

binwork91

Senior Member
Location
new york
Occupation
electrical engineer
Hi, I need some assistance with a code-related question.


Could you provide the code sections that address performing an arc-flash study only on equipment installed in compliance with the NEC, without any violations?


A building has an electrical system with some NEC violations. I would like to inform the building owner that these violations must be corrected first; otherwise, any new arc-flash labels cannot be considered reliable based on the current installation.

Thank you
 
Violation #1 - No Arc Flash Study!

They may require the study done first in order to safely mitigate the other violations. Just study it as-is and give them a report instead of stickers. Then do it over after the corrections are done and give them the permanent stickers.
 
From the 2023 NEC:
110.16 Arc-Flash Hazard Warning.
(A) General.
Electrical equipment, such as switchboards, switchgear, enclosed panelboards, industrial control panels, meter socket enclosures, and motor control centers, that is in other than dwelling units, and is likely to require examination, adjustment, servicing, or maintenance while energized, shall be field or factory marked to warn qualified persons of potential electric arc flash hazards. The marking shall meet the requirements in 110.21(B) and shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.

(B) Service Equipment and Feeder Supplied Equipment.
In other than dwelling units, in addition to the requirements in 110.16(A), a permanent arc flash label shall be field or factory applied to service equipment and feeder supplied equipment rated 1000 amperes or more. The arc flash label shall be in accordance with applicable industry practice and include the date the label was applied. The label shall meet the requirements of 110.21(B).

Informational Note No. 1:
See ANSI Z535.4-2011 (R2017), Product Safety Signs and Labels, for guidelines for the design of safety signs and labels for application to products.

Informational Note No. 2:
See NFPA 70E-2021, Standard for Electrical Safety in the Workplace, for applicable industry practices for equipment labeling. This standard provides specific criteria for developing arc-flash labels for equipment that provides nominal system voltage, incident energy levels, arc-flash boundaries, minimum required levels of personal protective equipment, and so forth.

Enhanced content:
The available short-circuit current must be known at the time of installation to comply with the interrupting requirements of 110.9 and 110.10. This information is necessary to determine the incident energy and working distance for compliance with NFPA 70E for future work on the service equipment. Section 110.16(B) specifies the information that a label is required to provide. The date that the label was applied is important because, over time, available fault current can change.

Two different arc flash labels meeting the requirements of 130.5(H) of NFPA 70E are shown below. On the left, the label provides the available incident energy and working distance. On the right, the label provides the arc flash PPE category.

23127083902-2023_Exhibit_110.9_LINK-ONLY.jpg
 
JoeStillman said:
Violation #1 - No Arc Flash Study!

They may require the study done first in order to safely mitigate the other violations. Just study it as-is and give them a report instead of stickers. Then do it over after the corrections are done and give them the permanent stickers.
Click to expand...

yes, but I want to have code section for reference.
 
TealHeals said:
From the 2023 NEC:
110.16 Arc-Flash Hazard Warning.
(A) General.
Electrical equipment, such as switchboards, switchgear, enclosed panelboards, industrial control panels, meter socket enclosures, and motor control centers, that is in other than dwelling units, and is likely to require examination, adjustment, servicing, or maintenance while energized, shall be field or factory marked to warn qualified persons of potential electric arc flash hazards. The marking shall meet the requirements in 110.21(B) and shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.

(B) Service Equipment and Feeder Supplied Equipment.
In other than dwelling units, in addition to the requirements in 110.16(A), a permanent arc flash label shall be field or factory applied to service equipment and feeder supplied equipment rated 1000 amperes or more. The arc flash label shall be in accordance with applicable industry practice and include the date the label was applied. The label shall meet the requirements of 110.21(B).

Informational Note No. 1:
See ANSI Z535.4-2011 (R2017), Product Safety Signs and Labels, for guidelines for the design of safety signs and labels for application to products.

Informational Note No. 2:
See NFPA 70E-2021, Standard for Electrical Safety in the Workplace, for applicable industry practices for equipment labeling. This standard provides specific criteria for developing arc-flash labels for equipment that provides nominal system voltage, incident energy levels, arc-flash boundaries, minimum required levels of personal protective equipment, and so forth.

Enhanced content:
The available short-circuit current must be known at the time of installation to comply with the interrupting requirements of 110.9 and 110.10. This information is necessary to determine the incident energy and working distance for compliance with NFPA 70E for future work on the service equipment. Section 110.16(B) specifies the information that a label is required to provide. The date that the label was applied is important because, over time, available fault current can change.

Two different arc flash labels meeting the requirements of 130.5(H) of NFPA 70E are shown below. On the left, the label provides the available incident energy and working distance. On the right, the label provides the arc flash PPE category.

23127083902-2023_Exhibit_110.9_LINK-ONLY.jpg
Click to expand...
This is arc flash and label requirement.
I like to see the code talking about arc flash label only for system without violation.
 
roger said:
I don't understand what you're asking if 110.16 is not what your looking for.
Click to expand...
110.16 only states that an arc-flash label is required, but it does not say that the system itself must be code-compliant.

I mean, you can perform an arc-flash study if you have OCPD, short-circuit, and feeder information. You can calculate the incident energy using this data, but the results will be unreliable if the system has code violations.

Therefore I need a code section clear state arc flash label is only for code comply system.
 
binwork91 said:
Hi, I need some assistance with a code-related question.


Could you provide the code sections that address performing an arc-flash study only on equipment installed in compliance with the NEC, without any violations?


A building has an electrical system with some NEC violations. I would like to inform the building owner that these violations must be corrected first; otherwise, any new arc-flash labels cannot be considered reliable based on the current installation.

Thank you
Click to expand...
I have not seen it in NEC yet, but I think NFPA 70E 110.2(B) can be applied. One can interpreted that if one or more NEC violation in such a way that render the equipment not in normal operating condition, then establish an electrical safe work condition is a must per NFPA 70E 110.2(B). In other words, no work is allowed on energized equipment that is not in normal operating condition. Since no work is allowed while being energized, then even there is an arc flash label on it, no one is allowed to work on such equipment while it is energized.
 
NFPA 70E goes into deeper detail with available fault current (AFC) calculations. You need to know your AFC before assessing the arc flash boundaries.

I hear you, though. You're wanting some other code or rule to address the existing equipment that you see is not to code. It might be an OSHA issue at this point because OSHA knows NFPA 70E exists and expects employers and owners of equipment to do their basic diligence.

NFPA 70E 2024

130.5 Arc Flash Risk Assessment.​

(A) General.​

An arc flash risk assessment shall be performed:
(1) To identify arc flash hazards
(2) To estimate the likelihood of occurrence of injury or damage to health and the potential severity of injury or damage to health
(3) To determine if additional protective measures are required, including the use of PPE
 
don_resqcapt19 said:
What code violation would make the results of an arc flash study unreliable?
Click to expand...
For example, improper OCPD, working clearance violations, and so on.


What is your opinion? Do you think NEC violations have nothing to do with the results of an arc flash?


Software will give your the label, incident energy number and so on. But is it reliable if there is violation?
 
Another concern is that arc flash calculations are based on data from tests.


Should those tests be set up in accordance with code requirements?


If compliance with the code is one of the test conditions, then the data would apply only to systems with no violations.

Correct me if I am wrong.
 
I see what I think is a hole in this thread. As far as I know, neither 110.16 or any other NEC section, requires a short circuit or coordination study. The labeling required is only the one on the right in post #2. So the OP's question doesn't have a code reference answer. As such Binwork91's obligation is to inform the owner that if they wish for energy potential warnings then any distribution equipment upstream of the panels in question must have a short circuit study done as well. It is NFPA 70E that discusses short circuit labelling.
 
binwork91 said:
For example, improper OCPD, working clearance violations, and so on.


What is your opinion? Do you think NEC violations have nothing to do with the results of an arc flash?


Software will give your the label, incident energy number and so on. But is it reliable if there is violation?
Click to expand...
I don't think the NEC has what you are looking for. But the things you mention in your example will definitely affect the results of your calculation. The owner needs to know what Arc-flash conditions actually exist - especially if they are embarking on a violation correction program.

Your calculation can only be as accurate as the info you are given, so when you say "improper OCPD" do you mean you were given the proper value but found out the existing condition was "improper"? You need to do your calculations based on what actually exists.
 
JoeStillman said:
I don't think the NEC has what you are looking for. But the things you mention in your example will definitely affect the results of your calculation. The owner needs to know what Arc-flash conditions actually exist - especially if they are embarking on a violation correction program.

Your calculation can only be as accurate as the info you are given, so when you say "improper OCPD" do you mean you were given the proper value but found out the existing condition was "improper"? You need to do your calculations based on what actually exists.
Click to expand...
It is an existing building with existing system. We sketched the complete existing system with all necessary information required for the arc flash study. The building doesn't have one-line or riser for us.
Everything included in the study is based on as-built conditions, which is why these violations cannot be corrected in a short period of time.
 
If the equipment is rated for the fault current, there is no other NEC violation that needs to be considered.

Arc Flash is only dependent on the OCPD clearing the fault. The impedance of improperly applied conductors is taken into account in the arc flash calculations. Improper working space issues maybe part of NFPA 70E Safe Work Practices but these distances are not considered in the Arc Flash Incident Energy calculations they don't impact the label.
 
binwork91 said:
For example, improper OCPD, working clearance violations, and so on.
Click to expand...
They have no effect on the arc flash calculation. Those things increase the danger if there is an arc flash event.
binwork91 said:
What is your opinion? Do you think NEC violations have nothing to do with the results of an arc flash?
Click to expand...
Not really...the arc flash calculations are based on the available current and the clearing time of the OCPD.
binwork91 said:
Software will give your the label, incident energy number and so on. But is it reliable if there is violation?
Click to expand...
Give me an example of a violation that changes the results of the arc flash calculation?
 
jim dungar said:
If the equipment is rated for the fault current, there is no other NEC violation that needs to be considered.

Arc Flash is only dependent on the OCPD clearing the fault. The impedance of improperly applied conductors is taken into account in the arc flash calculations. Improper working space issues maybe part of NFPA 70E Safe Work Practices but these distances are not considered in the Arc Flash Incident Energy calculations they don't impact the label.
Click to expand...
I am not sure what will happen if the OCPD does not perform as expected.

For example, if the OCPD cannot withstand the fault due to a low AIC, will it open the circuit faster or slower? In that case, is the TCC still valid for calculating the fault-clearing time?

Same idea for 208v fuse in 480v system.
 
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