Using a Third-party Field Equipment Evaluation as an Alternative to UL508A: Ensuring Electrical Safety and Compliance


Whether you're an OEM or a manufacturer, understanding the details of third-party field equipment evaluations as an alternative to UL508A can save you time, money, and headaches. In many cases, electrical panels on manufacturing equipment imported to the U.S. from other countries reach the end user’s site without an NRTL (or UL) marking. These panels will fail electrical inspections, and most of the time a licensed electrician will not even connect power to them. If that happens to you, a third-party field equipment evaluation can help get the project back on track.

In this in-depth guide, we'll take you through the process of performing a third-party field evaluation, providing you with expert-level insights and actionable steps to guarantee your electrical equipment meets the required safety standards.

Who Is Involved in a Third-party Equipment Evaluation?


A Nationally Recognized Testing Laboratory (NRTL) is a private-sector organization that is recognized by OSHA and meets the legal requirements in 29 CFR 1910.7 to perform testing and certification of products using consensus-based test standards. Equipment bearing the CE (Conformité Européenne) marking does not meet OSHA’s requirements as it is a manufacturer’s self-certification and not a third-party certification.

It is important to note that OSHA's acknowledgment of a NRTL does not constitute a bestowal of governmental authority; instead, it's a recognition of the organization's competence to carry out testing and certification of product safety within the scope outlined by its OSHA recognition.

Independent Field Evaluators

Field Evaluators are third-parties that perform equipment evaluations, and follow NFPA 791 (Recommended Practice and Procedures for Unlabeled Electrical Equipment Evaluations) to determine compliance. Field equipment evaluations must be performed under the responsible charge of a properly licensed Professional Engineer. Electrical Engineering and Electrical Safety companies offer this as a service. Unlike UL508A-listed control panels which are built in UL-listed shops, the field equipment evaluation takes place onsite at the final point of installation rather than in a shop setting.


The AHJ is the Authority-Having Jurisdiction. This is typically the local electrical inspector but could also be another party that has statutory authority. When it comes to field equipment evaluations, the AHJ uses NFPA 791 as a framework for inspections performed by Independent Field Evaluators.

OSHA requires electrical equipment in manufacturing or workplace environments to be labeled by an accredited Nationally Recognized Testing Laboratory (NRTL). An electrical inspector or AHJ will remove equipment from service if the electrical panels are found not to be labeled.

How to Get Third-party Evaluations

Selecting a Field Evaluator with a proven track record and expertise in evaluating equipment is crucial. They need to be a licensed Professional Engineer in the location where the equipment will be installed. If you don't know where to start, you can contact the State Department of Labor, the local Electrical Inspector, or an Electrical Contractor for recommendations.

Preparing for the Evaluation Process

Gathering Documentation

As you prepare for the evaluation, compile all pertinent documentation. This includes panel design drawings and panel component specifications. These documents will serve as the foundation for the evaluation process, providing a comprehensive overview of your equipment. The Field Evaluator will advise what other documentation may be required for evaluation and compliance.

Evaluation and Testing

The evaluation will take place at the installation site of the equipment. It will identify if the equipment is compliant with the applicable published standards, such as:

  • NFPA 70 2020 Edition (NEC)
  • NFPA 79 2021 Edition – Electrical Standard for Industrial Machinery
  • UL 508A – Edition 3 (2018) Industrial Control Panels
  • UL 1740 – Edition 4 (2018) Robots and Robotic Equipment
  • UL 61010-1 – Edition 3 (2012) Safety Requirements for Electrical Equipment for Measurement, Control, and Laboratory Use - Part 1: General Requirements

The main items which will be evaluated are:

  • Enclosure is suitable for the environment.
  • Enclosure is designed with appropriate ventilation.
  • Critical components are listed.
  • All the electrically live parts are enclosed within the enclosure.
  • All possible casualty hazards and any electrically live parts are guarded, or warnings are provided in accordance with the
  • Overcurrent protection provided is appropriately sized for the circuits and is of the proper rating and type.
  • Noncurrent-carrying metallic parts of the equipment have been checked and determined to be suitably bonded to the supply equipment grounding conductor.
  • Wiring will be inspected to ensure its voltage and temperature ratings and appropriate wire bending space was observed.
  • Any component or part of the equipment that was or appeared to be damaged will be checked and determined if it is acceptable for use.
  • Available fault current is below the manufacturer calculated SCCR.
  • The evaluation may also include non-destructive tests performed in the field. These tests may include testing the function of interlocks, light curtains, and emergency stops.

Compliance Report

Evaluation Report

Following the evaluation, the Field Evaluator will provide you with an evaluation report. This document will outline the results of the assessment, highlighting any areas of non-compliance that need attention. The report should include at least the following items:

  • Identification of the company performing the evaluation
  • Inspection location
  • Date of inspection
  • Project number and identity of person preparing the report
  • Specific equipment inspected
  • Standards used in the evaluation
  • Evaluation results of the construction of the panel
  • Performance tests conducted (if applicable)
  • Label number(s) applied
  • Controlled report number
  • List of compliance discrepancies

If the evaluation finds that the equipment complies with the referenced standards, the equipment is labeled and a detailed engineering report and statement of conformity is issued to both the end user and the AHJ recommending that the equipment be allowed to be installed and operated.

If the evaluation finds the equipment does NOT comply with the referenced standards, a list of deficiencies and potential corrective action will be proved. This information can be used as a roadmap for the end user to determine the proper corrections needed for each discrepancy. In some cases, it is prudent to contact the equipment OEM to ensure that any modifications do not void the equipment warranty. The Field Evaluator and the person correcting any discrepancies must be separate independent parties.

It is up to the end user to ensure that all discrepancies are corrected per the report and to request a follow-up evaluation by the Field Evaluator. During the follow-up evaluation, if all discrepancies are corrected, the evaluator will field-label the equipment and issue the compliance report to the end user and the AHJ recommending that the equipment be allowed to be installed and operated.

Keep Your Facilities Safe and Your Products Moving with Excel Engineering

Obtaining third-party field evaluation of your unlisted electrical equipment is an effective way to quickly satisfy the electrical inspector or AHJ and for you to ensure safety and compliance. As an independent field evaluator, Excel Engineering specializes in providing onsite third-party field evaluations for our clients to help keep their facilities safe and compliant with national and local standards.

Since 1990, Excel Engineering has helped our industrial manufacturing and OEM clients bolster their workforces and processes in a way that saves on labor costs, improves efficiency and safety, and ultimately produces a better bottom line. From electrical design and industrial automation to power systems studies and construction management, we have everything you need under one roof, and are just the right size to deliver on it day in and day out.

Contact us today to learn more.

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