110.21 Marking

This section includes two first level subdivisions to address equipment markings and field-applied hazard markings.  Markings are important for safety of those interacting with electrical equipment.

(A) Equipment Markings

The provisions within 110.21(A) are those markings to help identify the product. These markings must be able to withstand the environment in which they are place. The organization responsible for the original manufacture of the product or the reconditioning of the product.  This organization must be identified via one of the following methods:

Manufacturer’s name


Other descriptive marking 

If reconditioned it has to be identified as being reconditioned and the date that it was reconditioned.

In addition, other important markings that must be located on the equipment include those important for the proper application of the product.  These include the following:




Other ratings as specified elsewhere in NFPA 70

If the product has been reconditioned, the original listing mark must be removed or made unreadable.  This section makes it clear that the original nameplate is not required to be removed.

The only exception is for industrial occupancies where conditions of maintenance and supervision ensure that only qualified persons service the equipment.  In this case the marking for reconditioned equipment is not required for equipment that is reconditioned by the owner or operator as part of a regular equipment maintenance program.

(B) Field-Applied Hazard Markings

Field-applied hazard markings are important for safety and include caution, warning, or danger hazard markings that are, for example, required elsewhere in NFPA 70.  This first level subdivision requires that these markings be durable and withstand the environment.  These markings are not permitted to be handwritten unless portions of the markings are vaiable or subject to change.

NFPA 70-2023 Changes

The public input that drove this change was the result of a task group formed by the NFPA Standards Council in Decision D#19-11. The task group focused on requirements that cover the use of reconditioned electrical equipment throughout the NEC. 

The changes during this cycle can be found Contents of (A)(2). Reconditioned equipment requirements were moved into a list format. The permission to make the original listing mark permanently illegible was also provided to appease the concerns of motor manufacturers.  The listing mark is commonly a part of the motor nameplate which even when reconditioned often remains with the motor.  Previous language could have been interpreted to require the nameplate to be removed because it has the listing mark.  Informational notes were added to add clarity.

Information note No. 3 was removed as the 2020 NEC Style Manual requires that Informational Notes not include requirements.  The word “may” located in that informational note was the contentious part of the sentence.

The changes found in 110.21(B) are editorial in nature.

This change helps in the application of motors because most motor nameplates include the listing mark.  Now they don’t have to remove the motor nameplate to meet the language that says you have to remove the listing mark.  Just make it illegible.