UL considers an industrial control panel:
An assembly incorporating two or more pieces of industrial control equipment or related control circuit devices, provided with interconnecting wiring and terminals for connections in the field. To allow the installer to properly install the panel in accordance to National Electrical Code and other codes, electrical ratings and instructions are to be clearly explained on the panel. Installation can be completed in two ways: in an enclosure as “enclosed type” equipment, or arranged onto a mounting panel as “open type” equipment. For “open type” equipment, the assembly is installed in an enclosure provided by others, or at the installation site.
The UL Listing Mark on an industrial control panel provides evidence of third party certification to the municipal inspection authority and to the purchaser of the panel. It shows that the panel complies with an acceptable safety standard. The Listing Mark may be applied to a wide variety of designs — ranging from custom built, one-of-a kind panels, to standardized designs with only minor variations.
The UL Listing Mark on an “enclosed type” control panel only covers the enclosure and the components that are installed within the enclosure or to the enclosure at the manufacturer’s facility.
The UL Listing Mark on an “open type” control panel only covers the mounting panel and those components that are mounted to it at the manufacturer’s facility.
Please note that the UL Listing Mark does not include coverage for externally connected loads, even if provided by the panel manufacturer. Also, the UL Mark does not include coverage of any components shown on the wiring diagram that are indicated as being customer provided or as not being in the panel. If a complete equipment Listing is required, please contact us regarding our Factory Automation Equipment program.
General use industrial control panels rated not more than 600 volts and for installation in ordinary locations are specified in the Outline of Investigation for Industrial Control Panels, Subject 508A. The requirements in the Outline are based on the Standard for Industrial Control Equipment, UL 508, the National Electrical Code, NFPA 70, and the Standard for Industrial Machinery, NFPA 79.
An additional document is written for each individual panel builder and is intended to contain additional construction requirements and specific UL Recognized Components that have been found acceptable as a result of an engineering investigation.
You may find it helpful and cost beneficial to review the material contained in the UL 508A Outline to determine that your product conforms to these requirements. Copies can be obtained from comm 2000.
When UL receives your signed application form, along with a preliminary deposit check in the amount indicated on the application form, we will open an engineering investigation to establish Listing service for your facility. If you wish, we can reference a purchase number on our paperwork. However, we do require a check for the preliminary deposit before we can proceed.
If a representative sample of your panel constructions will not be ready for some time, it would be better to delay returning the application form and preliminary deposit until a week or less before the sample is available for examination.
Normally the investigation will be completed approximately six weeks after receipt of the signed application form. However, if you require panels to be labeled in less than six weeks, please let us know the date you require Listing on your application form. We will work with you to expedite completion of the investigation. To cover the extra time and effort involved, “rush” jobs will require an increase in the engineering cost limit.
The cost limit, specified on the application form, is established based on the assumption that all the components used in the panel are either UL Listed or Recognized and used as intended within their marked ratings. This cost limit assumes only a single day will be needed at your facility for the required engineering visit. Additional costs that are not covered in the Cost Limit include travel expenses and other non-engineering charges.
Follow-up services charges for the factory examination program begin after your product becomes authorized to use our Marking. The cost of the Type L Follow-Up Service is defrayed by a yearly service charge for each facility. There is also a per visit charge for conducting examinations at the factory, and a nominal charge for Listing Marks.
An engineering visit is made to the manufacturing facility to examine a representative panel design and answer any questions you may have about 508A. After examining the panel, we will provide comments on any features that are not in compliance with our requirements.
It is helpful to have schematics available for review during this visit. In addition, it is a good idea to have a list of only the UL Recognized Components being used in the representative panel you give us for examination during the visit.
Another visit, called the initial Production Examination. is conducted by a local UL Field Representative before we authorize use of the Listing Mark on the panels. This examination can accommodate your production schedule, so be sure to give us your factory representative’s proper contact information, along with when your panels are scheduled for production.
Panels operating from a source of supply greater than 600 volts will be required to comply with UL 508, Standard for Industrial Control Equipment (up to 1500V) or UL 347, Standard for High Voltage Industrial Control Equipment (2.2-7.2 kV).
Panels intended for installation in a hazardous location or having circuits that will extend into a hazardous location are required to comply with different requirements. Please see the hazardous locations section for more information.
Extra requirements are applied to panels intended for the following special uses:
overhead crane control,
metal working machine tools, plastic injection molding machinery,
flame safety supervision control,
power press, and
service equipment use.
If you intend to build any of these kinds of panels, please contact us for additional information on applicable requirements.
Once it has been determined that your product meets the necessary requirements, we will establish a Factory Follow-Up Service Examination Program to audit the continued compliance of your panels with the specifications developed during this investigation. You will receive a UL Procedure document that contains these specifications. The product will then be eligible to bear a UL Listing and/or Classification Mark.
A Each U.S. office maintains a stock of standard labels which may be obtained by sending your order and remittance to the office closest to you.