3rd Party Field Label Evaluation

Regardless of where you are located, we can perform your Field Label, safety sticker your equipment and produce the required report to the city quickly and efficiently.

Watch How We Perform Our Field Label Evaluations
Our FLE Label
Our Field Label Compliance Sticker

Why Would You Do Field Labeling?

Most cities require electrical field evaluations to protect the inhabitants of their city from disasters that can result from faulty electrical equipment. They are enforcing the NEC (National Electric Code) that states: All “conductors of electricity” must be “approved,” “identified,” “listed” or “labeled”. The code allows for a capable third party (LBIES) to perform an electrical evaluation of your product.

In addition:

  • It satisfies local and/or state electrical and building inspector’s requirements.
  • It protects your company, employees and building from potential catastrophes.
  • It assures safer and more reliable products.
  • It aids in defense of product liability action.
  • It is cost effective.
  • It gives the assurance that a product, process, or service conforms to all specified requirements.
  • To get an outside independent evaluation to ensure your money was well spent.

What is Field Labeling?

Field labeling is a safety review. Although its main area of interest is electrical, other important aspects of machine and operations safety are also covered in the labeling/permitting process. There are particular codes that are followed by all 3rd Party Inspectors, which do not vary.

These codes are as follows:

  • NFPA70 (The US “National Electrical Code”, which writes the rules for electricity)
  • UL 508A Safety of Electric Control Panels
  • NFPA 79/791 Safety of Industrial Machinery
  • ANSI Z535.4
  • OSHA requirements

What Does The Field Label Testing Look For?

Risk of Fire

  • Design/construction/voltage
  • Properly sized components
  • Appropriate non-combustible enclosures
  • Over-current/Overload protection & sizing

Risk of Shock

  • 30Vrms/60Vdc
  • Protection against accessibility
  • Appropriate enclosures
  • Articulated Finger Probe
  • Grounding

Risk of Mechanical Hazards

  • Pinch points/sharp points/Tip Hazard
  • Accessibility to moving parts – Crushing and Tearing Hazards
  • Appropriate Enclosures/Guards
  • Appropriate warnings and labels
  • Risk of High Current/Energy


  • Manufacturer/Model No./Electrical Ratings
  • Caution markings
  • Risk of Fire/Shock/Mechanical Hazards
  • Caution markings relevant to hazards within the installation site

What Is Evaluated In Field Labeling?

To ensure the electrical safety integrity of equipment, field evaluations focus on a number of key areas of the equipment construction.

The following summarize the fundamental methods of field evaluations:

  • Electrical Testing
  • Wiring
  • Over-current Protection
  • Lockout/Tag out
  • Labeling
  • EMO Tests
  • Other Hazards

Rules for Field Labeling

  1. Typically, products that are UL listed do NOT need a field label. BUT, if 2 or more UL listed tools are joined to perform a special action, the UL listing is nullified and the tools must be field labeled.
  2. Products that are custom built or one of a kind need a field label.
  3. If an Authority having jurisdiction (city inspector) says you need a UL or NRTL, they are saying you need a field label (see 1 and 2 above).

Field Labeling Testing Procedures

A breakdown of what is tested and the procedure followed are listed below so your team can determine if your equipment will meet all the codes.


  • Machine grounding is tested at numerous points on the equipment, including all exposed metal surfaces that enclose electrical components. Ground continuity testing is performed at 30 amps and is required to demonstrate ground resistance is less than 0.1 ohm at all points measured referenced to facility ground.
  • Surface leakage is tested to ensure that no more than 3.5mA of current exists on the exposed conductive surfaces of the equipment during non-fault operating conditions.
  • Input current is tested and the electrical design of the equipment evaluated to ensure the correct size of the main over-current device is employed. The electrical components and connections within the equipment are measured for acceptable heating to ensure that the electrical components are not operating at their stress levels during normal equipment operation.


  • Wiring methods are reviewed to ensure the requirements of NFPA 79 are met for conductor colors, incidental contact, segregation of control circuits and devices, ground conductors, labels, buttons, and indicators.
  • Isolation of hazardous voltages from earth ground as well as signal conductors are evaluated and tested through visual inspections and high potential breakdown testing to validate the visual inspection.

Lockout/Tag out

  • The equipment is examined to ensure that the facility feed conductors are provided with the correct clearances and termination points according to NFPA 70 and NFPA 79. The main disconnect handle and main LOTO provisions are examined for conformance to NFPA 70, NFPA 79, and OSHA requirements. The electrical enclosure(s) of the equipment is examined for suitability within the environment in which they are incorporated according to the conditions described in UL 508 and UL 50.
  • The full requirements of OSHA compliance for LOTO provisions on the hazardous energy on the equipment, as well as isolation for electrical energy are thoroughly reviewed. All of the energy that the facility provides to the equipment is examined and an evaluation of the ability to isolate all energy (process gasses, pneumatic gases, cooling water, process liquids, etc.) with lockable isolation features is done.


  • We identify all hazards on the system and review the equipment for Hazard Warning labels according to the potential hazards present on the equipment and ANSI Z535.4.

EMO Tests

  • Test the proper operation of any emergency stops for reliability and proper functioning.

Other Hazards

  • Special consideration is given to ground fault protection requirements on equipment that incorporates immersion heaters. Those systems that could create an unpredictable current path through liquid distribution lines are carefully evaluated to ensure that any faults in the heating system are mitigated before they become an electric shock hazard to personnel.
  • For equipment that uses flammable chemistry, the requirements to use electrical components that are listed for use in classified locations are examined in detail.
  • Where it is not possible to obtain components for classified locations, one of the requirements is that the equipment manufacturer has to produce the test reports that demonstrate adequate dilution of the flammable chemistry has been provided, and gives all pertinent information to conclude the evaluation.

Required Compliance And Safety Testing

In addition to relevant construction evaluations, the equipment will also be tested for compliance to safety requirements. The tests may vary depending on the type of equipment.

You can also learn more about what to expect during a field label evaluation from this blog here.

Some of the most common tests are:

Grounding Continuity Test:
Testing for proper grounding and bonding of the whole equipment.

Dielectric Voltage Withstand Test (Hi Pot Test):
Testing for adequate spacing between conductive parts. The test is performed between primary and ground and primary and secondary of the unit.

Input Current Test:
Measuring the input current of the unit during maximum load operation and evaluating the suitability of protection mechanisms such as fuses, circuit breakers, etc.

Strain Relief Test:
Measuring the strength and suitability of strain relief through push and pull tests.

Interlock Test:
Tests the suitability and performance of all interlocks giving access to live parts and moving components.

LBIES History of Field Labeling

In 1984 Lewis Bass International performed the very 1st Third Party Electrical Equipment Evaluation required in California. It was conducted on semiconductor tools for AMD – Sunnyvale, California.

Other cities adopted 3rd Party Evaluation requirements for all unlisted and custom equipment. It’s included requirements to industrial manufacturers, R&D, and medical devices. LBI was at the forefront and has evaluated thousands of different types of equipment.

Lewis Bass International Engineering Services is proud to continue offering this service to our clients as an approved Third Party Inspection Agency. We are known for being cost effective and minimizing turnaround time in completing the inspection(s) and getting the reports to the city so you can get equipment up and running.

Ready for a quote for field label services?

In a rush? Call us now at (408) 942-8000 for expedited service.

Lewis Bass International Engineering Services