UL1449 3rd Edition Overview

UL 1449 3rd Edition Requirements and Your Designs:
Littelfuse can help you meet the new standards


Article Sections:
Overview of UL 1449 3rd edition changes
Implications to design of end applications
Littelfuse options to help meet the new standards

Links to Additional Information:
UL1449 3rd Edition Overview Presentation
Article: Designing with Thermally Protected MOVs
Littelfuse UL1449 Approved Varistor Products Selector Table


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Introduction
A number of articles have been published regarding changes resulting from the release of Underwriters Laboratories UL 1449 3rd edition standard. These articles often suggest that the changes are so extensive it would be impossible for many existing designs to comply without major changes. In reality this is not so. Many existing devices indeed meet the new requirements, and merely require certification to the new edition of the standard.

This article is written to help educate readers about the standard changes and implications for design, and to serve as a guide to Littelfuse components and alternatives that meet the standard.


What is UL 1449?

Underwriters Laboratories standard UL 1449 has become the primary safety standard for surge protective devices (SPDs). It describes the materials and installation requirements for SPDs used for the protection of AC electrical circuits.

The standard has been revised twice in the past few years. A major safety testing initiative (UL 1449 2nd edition) became effective February 2007, and additional administrative and methodology changes (UL 1449 3rd edition) became effective in September 2009. The 3rd edition also includes new independent performance testing requirements.

UL 1449 3rd edition completely supersedes preceding editions. From September 2009 on, all equipment brought onto the market must satisfy these new requirements in order to qualify for the UL label.

Practically all North American surge standards now revolve around 3rd edition, and are now purposely aligned with other standards, including UL 1283, 2008 National Electrical Code™ Article 285, NEMA LS-1, ANSI/IEEE C62 documents and others.


Overview of Changes of UL 1449 3rd edition

Some of the primary changes in UL 1449 3rd edition include the following:

Terminology Change:The term for surge protectors has been changed from Transient Voltage Surge Suppressor (TVSS) to Surge Protective Device (SPD)

Inclusion of Surge Arresters:This change adds secondary surge arrestors within UL's SPD performance and safety standard. Contrary to some claims, this will not replace every secondary arrestor option currently on the market, though surge arrestors must meet Type 1 SPD specs (described below).

Creation of Four Type Designations:
Previous editions of UL 1449 classified surge protective devices into two types: permanently connected or cord-connected. The 3rd edition scraps that system and sorts SPDs into four types, depending on where they are located within an electrical distribution system:

Type 1 - Permanently connected SPDs intended for installation between the secondary of the service transformer and the line side of the service equipment overcurrent device, as well as the load side, including watt-hour meter socket enclosures and intended to be installed without an external overcurrent protective device.

Type 2 - 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 - Point of utilization SPDs, installed at a minimum conductor length of 10 meters (30 feet) from the electrical service panel to the point of utilization, for example cord connected, direct plug-in, receptacle type and SPDs installed at the utilization equipment being protected. The distance (10 meters) is exclusive of conductors provided with or used to attach SPDs.

Type 4 - Component SPDs, including discrete components as well as component assemblies.

Change in Clamping Voltage Testing: Tests under UL 1449 2nd Edition were conducted at 500A, 6,000V. The new tests are done at 3,000A, 6,000V. This is six times more surge energy, which results in higher clamping voltages. In addition, there is a change to the duty cycle requirement (see below). This is probably the most significant testing change.

Also, the results label has changed to "Voltage Protection Ratings (VPRs)" from "Suppression Voltage Rating (SVR)". Since the devices are the same, a higher surge current will produce a higher clamping level, and VPRs will be numerically higher than SVRs.

Standard UL 1449 2nd Edition (Old) UL 1449 3rd Edition (New)
Test 500A/6kV 3,000A/6kV
Title Suppressed Voltage Rating (SVR) Voltage Protection Rating (VPR)


Inclusion of Nominal Discharge Current Test (In): Another significant change is a stress test in which the unit under test (including the surge protector and any internal or external current-limiting devices) is subjected to several surges and temporary overvoltage events.

Type 1 devices are to be tested at 10kA or 20kA, while Type 2 devices can be tested at 3, 5, 10, or 20kA. The SPD manufacturer selects the type and the surge level for the product before testing. The SPD manufacturer also selects the MCOV (Maximum Continuous Operating Voltage) per mode to apply to the unit under test. Once those two parameters have been established by the SPD manufacturer, the test can start.

The device is subjected to 15 impulses at the specified discharge current, with MCOV applied between impulses; to pass the test the unit must be fully functional and the pre- and post-VPR clamping levels cannot vary by more than ±10%.

It is important to note that the test now includes any current limiting devices (internal or external); the overcurrent limiting device must be in the current path and be subjected to the same impulse as the SPD. This test is considerably more stringent than the earlier test, because it causes heat to accumulate in the SPD and associated devices.

UL 96A Lightning Protection Master Label impact:
In the past, UL 96A required that surge suppressors be evaluated as secondary arrestors. There were issues associated with different regulation and administration. Secondary arrestors now evolve into Type 1 SPDs, and UL 96A will accept Type 1 or Type 2 SPDs having 20kA nominal ratings.

First time approval as American National Standard (ANSI):
The third edition of UL 1449 is now an ANSI standard, and its official designation is ANSI/UL 1449 – 2006. As an ANSI standard it is subject to review and voting by a technical review panel, but as far as manufacturers and other users of SPDs are concerned it has little effect.


How UL1449 3rd Edition Affects Specifications

The new edition of UL 1449 presents several challenges to equipment designers.

The main challenge, other than new terminologies, is that new tests may result in existing products not meeting the new specifications.

--Performance ratings change — the new tests are more severe and the results will be numerically higher, thus unable to meet existing specifications. There are a number of classes of equipment for which the requirement for SPDs changes from type 3 to type 2. For example, manufacturers of products such as dimmer switches are discovering that their products are suddenly classified as Type 2 surge protection devices, when the varistors they have been using all along are Type 3.

--Contractors and distributors may waste time trying to meet obsolete specs, and customers may waste time trying to evaluate submittals.

--Manufacturers may get old or obsolete products, which might not be UL Listed, or supported in the future.

None of these changes are related to the safety of the product. In fact, most existing Littelfuse products meet the new standards without modification. For manufacturers, it's important to remember that Littelfuse has the expertise to guide manufacturers to a solution and has a full suite of type 1, 2, 3 4 and other devices that can help in their situation.

The UL 1449 3rd edition intermediate current abnormal overvoltage test requires that a SPD be subjected to a series of abnormal voltage events of a level insufficient to cause full breakover but sufficient to cause the device to conduct a substantial current, which it must withstand over a specified number of cycles without being damaged or destroyed. This may require a change in the type of SPD selected, although the approval situation for certain devices is presently in flux. Suffice it to say that Littelfuse offers a wide selection of components for overvoltage protection that are suitable for almost all applications.

Littelfuse Device Options
This section offers details about the Littelfuse devices that can serve each of the four new UL1449 type designations, and is designed to aid you in proper selection. Please click on the entries in the "Series" column to be directed to the details product page and data sheet.

Click here to the UL report on Littelfuse products

 

UL SPD Type

Intended for End use SPD Type

Series

Disc Size (mm)

Part Number

Rated Voltage (Vac)

Single Peak Current (8x20μs)

In Current (UL Nominal Discharge Current)

UL Operating Duty Cycle Test Current

From

To

Amps

Amps

Amps

Type 4

Type 1, 2 or 3 application

FBMOV

Dual 25

FBMOV*M

115

750

40000

10000

n/a

SMOV25

25

SMOV25S*

115

750

20000

10000

n/a

SMOV34

34

SMOV34S*

115

420

40000

20000

n/a

SMOV34

34

SMOV34S*

460

750

40000

10000

n/a

TMOV25S

25

TMOV25S*

115

750

20000

10000

n/a

TMOV34S

34

TMOV34S*

115

750

40000

10000

n/a

Type 4

Type 2 or 3 application

TMOV20

20

TMOV20R*

115

750

10000

3000

n/a

Type 4

Type other application

TMOV14

14

TMOV14R*

115

420

6000

2000

n/a

Type 5

Type 1, 2, 3 or 4 application

HA Series

32

V*32

110

750

25000

10000

n/a

HC Series

32

V*32

110

750

25000

10000

n/a

DHB Series

34

V*DHB34

110

750

40000

20000

n/a

HA Series

40

V*40

110

750

40000

20000

n/a

HC Series

40

V*40

110

750

40000

20000

n/a

HB Series

34

V*34

110

750

40000

20000

n/a

HF Series

34

V*34

110

750

40000

20000

n/a

HG Series

34

V*34

110

750

40000

20000

n/a

UltraMOV25

25

V25S*P

115

750

22000

10000

n/a

DA Series

40

V*DA40

130

750

40000

20000

n/a

DB Series

40

V*DB40

130

750

40000

20000

n/a

BA Series

60

V*BA60

130

320

50000

20000

n/a

BA Series

60

V*BA60

420

880

70000

20000

n/a

BB Series

60

V*BB60

1100

2800

70000

n/a

n/a

Type 5

Type 2, 3 or 4 application

CIII Series

14

V*C*

130

1000

6500

3000

n/a

UltraMOV

14

V14E*

130

625

6000

3000

n/a

UltraMOV

20

V20E*

130

625

10000

5000

n/a

CIII Series

20

V*C*

130

1000

10000

5000

n/a

LA Series

20

V*LA*

130

1000

6500

3000

n/a

ZA Series

20

V*ZA*

50

115

6500

3000

n/a

Type 5

Type 3 or 4 application

LA Series

14

V*LA*

130

1000

4500

n/a

3000

RA Series

22

V*RA22

130

275

6500

n/a

3000

SM Series

20

V*SM20

175

320

6500

n/a

5000

Type 5

Type 4 or other application

ZA Series

5

V*ZA05*

10

40

100

50

n/a

ZA Series

5

V*ZA05*

50

140

400

100

n/a

ZA Series

7

V*ZA*

10

40

250

100

n/a

ZA Series

7

V*ZA*

50

115

1200

500

n/a

ZA Series

10

V*ZA*

10

40

500

150

n/a

ZA Series

10

V*ZA*

50

115

2500

1000

n/a

CIII Series

10

V*C*

130

680

3500

2000

n/a

ZA Series

14

V*ZA*

10

40

1000

500

n/a

ZA Series

14

V*ZA*

50

115

4500

2000

n/a

ZA Series

20

V*ZA*

10

40

2000

1000

n/a

Type 5

Type 4 or other application

CH Sereis

8

V*CH8*

14

17

100

n/a

25

CH Sereis

8

V*CH8*

20

40

100

n/a

50

CH Sereis

8

V*CH8*

75

275

250

n/a

100

LA Series

7

V*LA*

130

480

1200

n/a

500

UltraMOV

7

V07E*

130

510

1750

n/a

500

LA Series

10

V*LA*

130

680

2500

n/a

1000

UltraMOV

10

V10E*

130

625

3500

n/a

1000

RA Series

8

V*RA8

140

275

1200

n/a

500

RA Series

16

V*RA16

140

275

4500

n/a

1500

ZA Series

5

V*ZA05*

150

460

400

n/a

250

SM Series

7

V*SM7

300

385

1200

n/a

500

SM Series

7

V*SM7

420

510

1200

n/a

400


  

Notes: 

1 "Others" is defined as SPDs investigated for use in other than SPD applications where surge tested at the manufacturer's stated rating as detailed in the table below.
* Denotes voltage and ** denotes relative energy. Please refer to product data sheet for additional information.

Links to Additional Information:
Scope definition of the UL1449 3rd edition specification
Table of contents for UL1449