3rd Party Field Label Evaluation

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.  We continued to do electrical evaluations for AMD and many other FABS,  When the cities spread the requirements to industrial manufacturers, R&D, and medical devices, LBI was in the forefront and has evaluated hundreds of thousands of all different kinds of equipment.  

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.  Because we have been doing Field Labels longer than anyone (we do over 2000 machines a year), we know how to get you through the process with the least amount of disruption to your company.

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

Rules for Field Labeling:

  1. 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 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)
  4. Table top tools or tools that roll do not need a field label

Why would you do Field Labeling?

Most cities require Field Labeling 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:

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.

Lewis Bass International Engineering Services provides this service.  We are an approved Third Party.  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.  Call our Customer Service Department at 408-942-8000.

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.



Lockout/Tag out


EMO Tests

Other Hazards

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. However, 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. 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.

What does the Field Label Testing look for?

Risk of Fire

Risk of Shock

Risk of Mechanical Hazards


Now that you know more than you ever wanted to know about 3rd Party Field Labels, let LBIES provide this service.  You now have all the information needed to help you understand about Field Labeling.  If you have any technical questions, please call 408-942-8000, and ask for any of our engineers and they will be glad to help you.  Call Lewis Bass International Engineering Services if you are not sure if your city requires Field Labeling or if you are not sure if the city you are sending your equipment to requires it.