February 9, 2007 - A New Era in SPD Safety

A little history...

In 1998 UL 1449 began adding Short Circuit Current Ratings to the list of requirements. This was also a big NEC issue with the advent of NEC 285 - Surge Protective Devices. Manufacturer's of UL 1449 Listed products are entering a new phase in safety testing with the addition of UL 1449 Second Edition Revised - February 9, 2007. Beginning with this date, all UL 1449 Listed devices must comply with new requirements.

What's new...

Under the previous revision, TVSS/SPD products were tested with full phase voltage with both limited and high current tests. Products were tested with full phase voltage at .125A, .5A, 2.5A and 5A to evaluate containment. A cheesecloth is applied over the product being evaluated. Any smoldering, fire, soot, or conductive material expelled in the process of the testing and it's back to the drawing board. Because of NEC's new requirements, UL would also require manufacturer's to select a level of high current for Short Circuit Current Rating (SCCR) evaluation. Up to 200kA rms.

Under the new revision, TVSS/SPD products will no longer be required to test at .125A full phase voltage, but will now add 10A at full phase. This test is to indicate what happens with the device when there's a limited fault occurring due to a distribution system anomaly. The real kicker though is intermediate fault current testing. These tests have been added to simulate open neutrals, loose neutrals, single-phasing, and system or products faults. UL now requires that products be tested with full phase voltage at 100A, 500A and 1000A. SCCR ratings are still electable up to 200kA for NEC purposes, but intermediate tests are fixed.

What's at issue...

Should you update your specification ? Yes. Should you have a better understanding of the issues ? Yes. Should you be better informed about construction of surge protection devices ? Yes. Should you have a better handle on neutral bonding and grounding issues that relate to surge protection ? Absolutely.

Without knowing enough about surge protection devices, their application, installation, and construction, specifiers open themselves up to prior knowledge issues that are easily quelled through a proper understanding. The behavior of suppression components used in varying designs is something that's relatively fixed and unchanging. The physics on the behavior of excess electrons propelled into distribution systems as transients is part phenomena, yet measurable and somewhat predictable due to distribution system limitations.

What to do...

Use our weblink: http://www.apttvss.com/training/UL1449-2.5/html

Choose a date listed on our calendar for interactive training, or simple choose our self-taught presentation to make yourself more familiar with important surge protection issues.

If you are a P.E. in a state that requires approved CEU's for renewal, please contact our Engineering Support Group by email or phone:

petraining@apttvss.com or 800-237-4567... ask for Lou, Ken, or JD.