Industry Standards Changes - 2009
UL 1449 Third Edition and 2008 NEC® Article 285 generated substantial changes.
•The term TVSS changed to SPD
•Types 1, 2, 3 & 4 SPDs are created
•UL 1449 clamping voltage performance testing changed from 500A to 3,000A
•UL 1449 added new Nominal Discharge Current testing (I nominal, or In), which consists of more rigorous
The SPD Type category is important to understand before installing any SPD. Type 1 and 2 SPDs are fully UL Listed devices whereas Type 4 SPDs are UL Recognized devices.
Type 1 – Installed on line or load side of the Main Overcurrent Protection (OCP), similar to obsolete products known as Secondary Surge Arrestors, except now includes rigorous safety testing. Includes all OCP & safety disconnectors inside the SPD.
Type 2 – Installed on load side of the Main OCP, similar to previous products known as TVSS. May or may not require external OCP. Type 3 – Point of Utilization, direct plug in type devices, surge strips, etc. Theses devices are intended for installation 10 meters from the panel (rationale based on IEEE Cat. A location).
Type 4 – Surge suppression components, could be a basic component or a complete module. Type 4 components can be tested for Type 1, Type 2 or Type 3 applications.
Figure 1: SPD Types
2008 NEC Art 285 & UL 1449-3
SPD Types: Types 1, 2, 3, & 4
Based on Location within electrical distribution system
(also coincides with ANSI/IEEE C62.41.2 - 2002 Categories C, B &A)
General Information
Product Family Outline
TPS3 12 – Single Module in enclosure
TPS3 15 – Two Modules in enclosure
Each is available with Standard modes (most common) or discrete
The TPS3 12 & TPS3 15 families are intended for use as a Type 1 external mount SPD. See Model Number Decoder in Table 1 (page 3).
Type 1 SPD
Type 1 SPDs include internal overcurrent protection and have been evaluated by UL to more stringent requirements. Type 1 SPDs are suitable for installation on the line side or load side of the service disconnect overcurrent device. Type 1 SPDs may be used in Type 2 applications.
Internal Protection
This device features internal overcurrent and overtemperature protection that will disconnect effected surge suppression components at the end of their useful life, but will maintain power to the load – now unprotected. If this situation is undesirable for the application, follow these instructions for servicing or replacing the device.
Service Guidelines
Service of this unit consists of replacing the internal module(s), disconnect switch (if equipped) and/or display assembly.
There are no
Simplified Explanation of Operation
As SPDs sense overvoltage, they create a momentary internal short circuit, thereby redirecting harmful surge energy to earth ground. SPDs are capable of repeating this function repeatedly. For optimum protection, staged surge suppression should be implemented at the service entrance and all other distribution or panelboard locations feeding sensitive equipment.
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