The History and Components of a Nameplate
Machine nameplates have a history dating back to their first use by St. Paul’s Stamp Works, which issued their first identification nameplate to a local company in the mid 1920s.
Much has changed since then. Nameplates are now a requirement for all consumer, industrial, medical, and high tech machinery worldwide. In the United States, the NFPA has issued formal nameplate content standards and new updates to nameplate requirements throughout the years.
What Information is Required on a Nameplate?
Nameplate information shall* include:
*The usage of shall in this case with regards to nameplate requirements per NFPA 79 means it is mandatory inclusion, not optional as should could imply.
- Manufacturer and serial number (model optional)
- Voltage, frequency, and phases
- Overcurrent protection size (Circuit breaker)
- SCCR (short circuit current rating)
- Full load and largest load current
- Electrical schematic number
|1. The full-load current shown on the nameplate shall not be less than the full-load currents for all motors and other equipment that can be in operation at the same time under normal conditions of use. Where unusual loads or duty cycles require oversized conductors, the required capacity shall be included in the full-load current specified on the nameplate|
|2. Nameplate must be plainly visible.|
A typical machine nameplate for a transformer.
A common example of an older electric motor nameplate.
Machine Nameplate Requirements According to NFPA 79
NFPA 79’s Chapter 16 Marking and Safety Signs section has clear guidance on the expectations and components required of a machine nameplate in North America, those of which include the following:
16.4 Machine Nameplate Data.
16.4.1 Control equipment shall be legibly and durably marked in a way that is plainly visible after the equipment is installed. A nameplate giving the following information shall be attached to the outside of the enclosure, or on the machine immediately adjacent to the enclosure: (1) Name or trademark of supplier (2) Model, serial number, or other designation (3)*Rated voltage, number of phases and frequency (if ac), and full-load current for each supply (4) Ampere rating of the largest motor or load (5) Maximum ampere rating of the short-circuit and groundfault protective device, where provided (6) Short-circuit current rating of the industrial control panel (7) Electrical diagram number(s) or the number of the index to the electrical drawings
16.4.2 The full-load current shown on the nameplate shall not be less than the full-load currents for all motors and other equipment that can be in operation at the same time under normal conditions of use. Where unusual loads or duty cycles require oversized conductors, the required capacity shall be included in the full-load current specified on the nameplate.
16.4.3 Where more than one incoming supply circuit is to be provided, the nameplate shall state the information in 16.4.1 for each circuit.
16.4.4 Where only a single motor or motor controller is used, the motor nameplate shall be permitted to serve as the electrical equipment nameplate where it is plainly visible.
16.4.5 Where supply conductor and machine overcurrent protection is furnished as part of the machine, the machine shall be marked “Supply conductor and machine overcurrent protection provided at machine supply terminals.” A separate nameplate shall be permitted to be used for this purpose
Nameplate SCCR Requirements
As mentioned in our blog Short Circuit Current Rating (SCCR) and Your Industrial Equipment , SCCR is a required nameplate item since the release of the 2005 NEC.
The short-circuit current rating (SCCR) is important to know when designing and installing an electrical control panel because of its role in over-current protection.
The SCCR is the maximum current (in amps) that an electrical device or control panel is able to withstand for three (3) VAC electrical cycles, or during the operation of an over-current protection device such as a fuse.
UL 508A, the standard for industrial control panels in the United States, provides the below instructions for determining the SCCR of a control panel:
1. Determine the SCCR of all individual power components and UL approved series ratings.
a. Examine all individual components and record their SCCRs.
b. If SCCR is not marked or known, use UL508A default Table SB4.1
c. Check and record any UL approved series ratings.
d. Note the minimum SCCR in the feeder circuit and each branch circuit.
2. Modify the SCCR of certain series combinations and record their SCCRs.
a. If current limiting fuses are used in the feeder circuit, compare the Ipeak of the fuse from UL 508A Table SB4.2 to the lowest rated SCCR component or minimum SCCR in each branch circuit.
b. The Ipeak of the fuse must be less than or equal to the lowest rated SCCR of any component or SCCR in each branch circuit.
3. The SCCR of the panel is equal to the lowest rated SCCR of any:
a Overcurrent protective device
b. UL approved series SCCR rating
c. Modified combinations from Step 2
d. Power component not affected by Step 2
Image Source: https://www.revereelectric.com/roller/UnilogBlog/entry/ul-508-and-nec-code
Nameplates and Inspection Requirements
When considering a third party electrical evaluation for a machine in your facility, it is important to ensure that nameplate is both visible and legible to a visiting inspector.
As listed above, the NFPA has an actual code addressing this exact scenario in section 16.4 entitled ‘Machine Nameplate Data’.
Let’s look into what this exact code specifies regarding visibility:
16.4.1 Control equipment shall be legibly and durably marked in a way that is plainly visible after the equipment is installed.
When seeking an inspection for your equipment that may not have a nameplate or an incomplete nameplate, a Lewis Bass engineer will request as much documentation and identifying materials as possible to establish a baseline for the machine to be tested against.
Once enough material has been collected to begin a formal electrical evaluation of the equipment, the machine operator will be expected to produce an accurate nameplate for future inspectors to take note of if the unlisted machinery happens to be moved or involved in an accident in the future.
A Lewis Bass Engineer Verifying Nameplate Data
Do You Need an Evaluation of Equipment at Your Facility?
Are you in need of an electrical evaluation for known or potentially unlisted equipment in your facility that may or may not have complete machine nameplates visible?