NEC 2026 new arc flash hazard markings required

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T

TealHeals

Member
Location
Oregon
Occupation
journeyman electrician & licensed signing supervisor
NEC 2026 110.16 will require labels on non-swelling unit service and feeder equipment. The new language reads:
"In other than dwelling units, a permanent arc flash marking must be applied to service and feeder equipment such as switchboards, enclosed panelboards, and meter socket enclosures. The arc flash hazard marking must be permanently affixed to the equipment and cannot be handwritten in accordance with sec. 110.21(B), be clearly visible to a qualified person, and be installed in accordance with applicable industry practices containing the following information: (1) nominal system voltage; (2) arc flash boundary; (3) Available incident energy or minimum required level of PPE; (4) date the assessment was completed."

In my opinion, a sub-panel would not qualify as "service and feeder equipment" - would you agree?

I'm at a place that builds mobile/modular buildings and we usually install a sub-panel that later gets fed from a meter main or distribution panel, depending on where the building site is. I'm trying to wrap my head around this new NEC requirement to decide if we need to label our sub-panels or not. I welcome your opinions.
 
A subpanel would be required to have it.

And the person pulling the permit for the feeder to the modular building would need to do the arc flash assessment.

Or your engineered drawings would need to include upstream devices on the submittal for the arc flash assessment. Which is probably not going to happen.

But typically, the Arc Flash assessment is the last thing completed because conductor routing can change and therefore modify the label.
 
Retirede and 117 - are you saying that in order for me to calculate the incident energy, I need to know the AFC? This portion of my education is so rusty!
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don_resqcapt19 said:
This change that will have a huge impact on smaller contractors that do design and build installations as the contractor will now have to calculate this information or pay someone else to calculate it.
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I was hoping to set up a spreadsheet or use the calculator online; yet it seems everybody has a software program to push.
 
MyCleveland said:
Question for anyone that performs these calcs...is IEEE 1584-2018 the most current document that outlines the required calculation parameters?
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My understanding is that the IEEE 1584-2018 is commonly used and it has more data points than other methods. The NFPA 70E 2024 edition says, "IEEE 1584-2018 is a revision of IEEE 1584-2002 as amended by IEEE 1584a-2004 and IEEE 1584b-2011." <- this is in Annex D
This was a helpful, quick article going into more depth of IEEE 1584: https://electricityforum.com/iep/arc-flash/ieee-1584
 
TealHeals said:
My understanding is that the IEEE 1584-2018 is commonly used and it has more data points than other methods. The NFPA 70E 2024 edition says, "IEEE 1584-2018 is a revision of IEEE 1584-2002 as amended by IEEE 1584a-2004 and IEEE 1584b-2011." <- this is in Annex D
This was a helpful, quick article going into more depth of IEEE 1584: https://electricityforum.com/iep/arc-flash/ieee-1584
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Thanks
 
You guys! I might have been thinking about this while overwhelmed. The 2026 NEC is requiring:

1. The nominal system voltage
2. The arc flash boundary
3. The available incident energy or minimum required level of personal protective equipment
4. The date the assessment was completed

And it can't be hand-written. The cost for printer + starter supplies (ribbon and durable vinyl) is going to be ~ $3,000. I'm in Oregon, so I'll be curious to know which part of this upcoming 110.16 will be adopted/amended on the state level.

I can use NFPA 70E, Table 130.7(C)(15)(a) to determine my arc flash boundary* and PPE category**

* this satisfies item #2 in NEC 2026 110.16
** this satisfies item #3 in NEC 2026 110.16, the latter part of the "or" statement: The available incident energy or minimum required level of personal protective equipment
 
TealHeals said:
And it can't be hand-written. The cost for printer + starter supplies (ribbon and durable vinyl) is going to be ~ $3,000. I'm in Oregon, so I'll be curious to know which part of this upcoming 110.16 will be adopted/amended on the state level.
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a bunch of years ago I needed a bunch of labels for some big wastewater clarifier drives (Lube Specs) and I just designed some crap with Paint on my computer and sent them off to somebody and had them just make them for us and it was cheap as far as I remember. That had to be maybe 2008. As advanced as things have gotten in the past 18 years, I'm sure you can find any kind of label you want on Alibaba and have them on your doorstep in a week, even faster if you want to pay more
 
There is no reason to spend $1000s to print labels. There are lots of local printers that can print labels for cheap.
We used to use thermal printers and then add a UV when outdoors.

The labels information is only good for 3-5 years so you don't need forever labels.
 
jim dungar said:
There is no reason to spend $1000s to print labels. There are lots of local printers that can print labels for cheap.
We used to use thermal printers and then add a UV when outdoors.

The labels information is only good for 3-5 years so you don't need forever labels.
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Yes, the clear bra tape from 3M is fantastic stuff.
 
TealHeals said:
You guys! I might have been thinking about this while overwhelmed. The 2026 NEC is requiring:

1. The nominal system voltage
2. The arc flash boundary
3. The available incident energy or minimum required level of personal protective equipment
4. The date the assessment was completed

And it can't be hand-written. The cost for printer + starter supplies (ribbon and durable vinyl) is going to be ~ $3,000. I'm in Oregon, so I'll be curious to know which part of this upcoming 110.16 will be adopted/amended on the state level.

I can use NFPA 70E, Table 130.7(C)(15)(a) to determine my arc flash boundary* and PPE category**

* this satisfies item #2 in NEC 2026 110.16
** this satisfies item #3 in NEC 2026 110.16, the latter part of the "or" statement: The available incident energy or minimum required level of personal protective equipment
Click to expand...
How are you using those tables without knowing the available short circuit current and clearing time of the upstream breaker?
 
For the single-phase subpanels, 120/240 volt, that we're using on our mobile/modular buildings - those tables don't require me to use the info from the upstream breaker.
NEC 2026 110.16 is asking for the arc flash boundary and the available incident energy or minimum required level of personal protective equipment.
That information can be obtained from NFPA 70E, Table 130.7(C)(15)(a)
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