The National Electrical Code (NEC) Article 600 and UL 48 Standard for Safety for Electric Signs are used to evaluate the field installation and construction of electric signs in the U.S. In Canada, the relevant guidelines are the Canadian Electrical Code (CEC) and CSA 22.2 No. 207.
All signs that are electrically operated and/or electrically illuminated are covered, regardless of voltage, including:
- High intensity discharge (HID)
- Light-emitting diode (LED)
- Cold cathode
Not included are:
- Illuminated clocks operating at 600V or less
- Exit signs
- Trailer of a trailer-mounted sign
- Luminaires mounted to function as outline lighting
- Luminaires mounted within an awning sign
- Luminaires intended for billboard illumination
- Fiber optics or fiber optic illuminators
- Signs for use in hazardous locations
- Procedures to ensure required testing is conducted and documented
- Test logs showing all required information
- Non-conforming products are reworked and tested
- All applicable personnel are trained to perform required tests
The latest edition of UL48 (15th edition) requires three tests: ground continuity (6.1-6.3), strain relief (5.4.1-5.4.4), and exclusion of water (5.9.1-5.9.2).
Documentation requirements include:
- Component traceability records
- Checklist for wiring diagrams, schematics and marking
- Personnel assigned to Sign Shop listing
- Checklist for sign documentation
- Sign label log
Certified (Listed) signs follow the marking requirements of NEC Section 600.4 and UL 48. A sign must be marked with the identification of the manufacturer or an identifying trade name or trademark, along with electrical voltage and current ratings. All required markings and the MET Certification (Listing) Mark are to be permanently applied to the exterior surface of the sign.
MET Certified labels are the manufacturer’s declaration of compliance and can only be affixed by the manufacturer at the place of production. The application of a MET Mark in the field is only permitted when an inspection is performed by one of MET’s Field Safety Group after a field evaluation.
MET Labs is widely considered the responsive alternative to UL, with a business-friendly service and allowance for use of any component that is certified by any Nationally Recognized Testing Laboratory (NRTL).