Issue 03 / May 2010
UL 1449 3rd Edition Changes: A Major Overhaul of Safety Standards for Surge Protective Devices
By Tom Phipps, VP Engineering, Thor Systems, Inc
A new surge suppression safety standard went into effect on September 29, 2009. Many engineering firms and consultants are now scrambling to update specifications to incorporate the changes required by the new standard. With UL continuing to make
changes to the newly released standard (and convening a Standards Technical Panel as recently
as last month), keeping ahead of the game is proving difficult. Here is a list of the major changes and how they will affect the specifying engineering community.
Major 3rd Edition Changes
The first change that most consulting engineers will notice is changing from the suppressed voltage rating
(SVR) to the voltage protection rating (VPR). The 3rd edition standard changed the waveform used to determine clamping voltage levels from 6000 volts/500 amps to 6000 volts/3000 amps. Changing from SVR to VPR means that the ratings must increase due to the six (6X) times higher energy level associated with the new waveform specifications. No 2nd edition permanently connected SPD will meet the requirements of the 3rd edition standard from a VPR standpoint. Consulting engineers now have to revise existing specifications to the new VPR rating levels. Also specifications are being updated to call out the UL 1449 3rd edition standard rather than the 2nd edition.
One of the major reasons for the release of the 3rd edition standard was to incorporate secondary surge arresters used at 1000 volts and below. Previously UL used an IEEE standard to test surge arresters. To institute this change surge arresters and TVSS devises were grouped together as Surge Protective Devices. Thus the title for the standard changed from the “Standard for Transient Voltage Surge Suppressors” to the “Standard for Safety for Surge Protective Devices”. Along with the change in title came a change in categorization as surge protective devices are now grouped by type:
- Type 1: Replaces the secondary surge arrester designation and must be permanently connected. SPDs intended for installation between the secondary of the service transformer and the line side of the service equipment over current device, as well as the load side, and cannot be installed with an external overcurrent protection device.
- Type 2: Designates permanently connected SPDs intended for installation on the load side of the service equipment overcurrent device, including SPDs located at the branch panel.
- Type 3: Designates plug-in and surge strip units intended for installation at an outlet. Point-of-utilization SPDs installed at a minimum conductor length of 10M (30 feet) from the electrical service panel to the point of utilization, e.g. cord-connected, direct plug-in, receptacle-type SPDs installed at the utilization equipment being protected.
- Type 4: Designates a component assembly consisting of one or more
- Type 5 components together with a disconnect (integral or external) that can comply with the limited current tests called out in the standard. Type 5: Designates a discrete surge suppression component such as an MOV or SAD, etc. that can used to construct a Type 1, 2, 3 or 4 device [denoted as “recognized” equipment today (UR)].
Finally the duty cycle test was replaced by the Nominal Discharge (In) test that consists of three sets of five impulses with a 30-minute wait time between sets. These sets of impulses are required for each mode of protection and each voltage code offered by the manufacturer.
- Type 1: 10kA or 20kA; 8/20 waveform as selected by the manufacturer
- Type 2: 3kA, 5kA, 10kA or 20kA; 8/20 waveform as selected by the manufacturer
- Type 3: Devices are required to survive (15) 6kV/3kA impulses
- Type 4: Tested for use at intended location (Type 1, 2 or 3)
- Type 5: .01kA, .05kA, 01kA, .15kA, .25kA, .5kA, 1kA, 1.5kA, 2kA, 2.5kA, 3kA, 5kA, 10kA, or 20kA; 8/20 waveform as selected by the manufacturer
The three sets of five impulses are applied at one minute intervals with Maximum Continuous Operating Voltage (MCOV) (manufacturer specified) being applied 250mS after the impulse. After the 15th impulse, MCOV is again applied for 30 minutes. Upon test completion, the VPR test is repeated and the results must be within 10% of the original test results.
Engineers that are specifying a UL 96A Lightning Protection System must also specify a Type 1 or Type 2 SPD with a Nominal Discharge (In) current rating of 20kA at the service entrance.
Conclusion
The UL 1449 3rd edition effective date of September 29, 2009 has come and gone. As of that date, 2nd edition specifications will no longer be acceptable to specify surge protection devices. Also SPD manufacturers will no longer be able to manufacture a 2nd edition product and maintain the UL listing after the September 29th effective date. Specifications must be updated so that an outdated product is not employed for a new application and effective and applicable performance ratings are still maintained. New specifications will need to reference all of the revisions including: VPR levels; Nominal discharge levels; and type designations to properly evaluate an SPD using the third edition requirements.
Visit Thor’s website for more information and to view downloadable information sheets.
