UL1449 3rd Edition Overview

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

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

Links to Additional Information:
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 2^nd edition) became effective February 2007, and additional administrative and methodology changes (UL 1449 3^rd edition) became effective in September 2009. The 3^rd edition also includes new independent performance testing requirements.

UL 1449 3^rd 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 3^rd 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 3^rd 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 3^rd 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.

Inclusion of Nominal Discharge Current Test (I_n): 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 3^rd 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