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Ask Pat - Our Resident Grizzled VeteranPat is a grizzled veteran of MET Laboratories, having participated in some of the toughest approvals and thorniest technical challenges.  Though eminently experienced, he doesn’t glory in his past accomplishments, but instead pours over the latest standards updates and electrical testing equipment advances.  Pat can sometimes be criticized for being overbearing, but rest assured, he is hardly ever wrong.

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Q: Do SELV (Safety Extra Low Voltage) products (such as a PCI card, which would be installed in a computer) require UL or CSA safety testing?
A: Maybe. Besides the matter of the voltage of the device in question, there is a potential concern with the energy of the circuit to which it attaches.
All SELV circuits are not created equal. Though a properly rated SELV circuit may not present an electrical shock hazard, the energy of the circuit in question may present a fire or an energy hazard. In these cases such cards/products may require an investigation for compatibility.
However, as a rule, and in the case of the accessory card for a personal computer, if the personal computer is listed by a recognized agency and the manufacturer of the computer intended for the product to be serviced or modified by users, then the accessory card slots should have been investigated with maximum possible load and overload considered. This would allow for most aftermarket accessory cards to be deployed, whether listed or not, and allow for a high level of confidence that the safety compliance of the overall product remains in good standing.
It is also possible that a retailer or other buyer might expect listing of such cards. Check computer manufacturer documents too. Some might specifically require that only listed accessory cards be used in their systems. This might be more of a warranty issue but if the manufacturer restricts such use then it is assumed that unlisted cards will not allow the product's overall safety certification to remain intact.
Lastly, consider what your competitor is doing. Are there other PCI cards that have certification? Maybe it is expected in the industry and if so, to be competitive, you may have to have such cards listed too. Check USB mice and keyboards and you'll see some that are listed and, probably many more that are not listed. The market tends to drive certification needs for these types of products rather than any law or regulation.

Q: The product is a test instrument operating at 24 Vdc connected to the mains through a detachable class 2 ac-dc converter that is not part of the product, but sold with it. The product has a rechargeable Lithium Ion battery. During its operation, the product is connected to a xDSL line (TNV). For European union, the product falls outside of the scope of the LVD directive. It is not terminal equipment as defined in the R&TTE directive. So for CE marking, is there any safety standard to meet?
A: If it’s not terminal equipment or otherwise does not fall within the scope of the RTTE Directive, and if it is not in the scope of the Low Voltage Directive, then at a minimum the General Product Safety Directive has to be addressed. This does not permit the application of a CE mark but it is still EU law.

Q: I was under the impression that Russia was to enforce new safety requirements on electrical products at the end of 2010. But that does not appear to be the case. Is this true?
A: The new Federal Law of the Russian Federation of December 27, 2009, N 347-FZ –"Technical regulation on safety of low-voltage equipment (LVTR)" and the new Russian GOST-R mark were to come into play on December 27, 2010.
But, on December 22, 2010 the Russian parliament Duma decided to postpone the implementation of this new regulation. This decision was approved by the Federation Council on December 24 and signed by president Dmitry Medvedev. The enforcement date was thus postponed to January 1, 2012. The process of GOST certification and its present logo is still in effect.

Q: Why is it that for NEBS certification, so many tests referenced in Telcordia GR-1089-CORE specify that testing be peformed with enclosure doors opened and closed? Why not just do all testing with doors closed, as would naturally be the case?
A: The concern with doors open vs. closed in a telecommunications central office is easy to understand. The regional bell operating companies (RBOC's) provide critical services, which cannot be interrupted. Even though the normal operation of the equipment installed in a central office is with its doors and covers closed, those small windows of time during installation and maintenance, where a technician has the doors and covers opened are still a concern. Ideally, the equipment must remain immune to the electromagnetic disturbances from other equipment and must not release uncontrolled levels of electromagnetic emissions, while its doors and covers are opened for even a few moments.
It is important to note within GR-1089 it states: “It is suggested that tests first be performed with doors and covers open. If the criteria are met with the doors and covers open, then the criteria with the doors and covers closed are considered to have been met. However, if the criteria with the doors and covers open are not met, it will be necessary to retest at least the failed frequencies with the doors and covers closed.” However, testing for ESD and Radiated Immunity still require that the unit must pass with the doors open.

Q: Do keyboards and mice require UL/CSA compliance? Does it matter if they are USB or PS/2? I have seen many keyboards that only have FCC compliance, but no UL compliance.
A: The need for safety certification in the case of keyboards and mice is driven by the industry, usually buyers like retail outlets. It does not seem to matter if they are USB or PS/2. If you are a manufacturer it might be necessary to have the products certified because that is what the competition is doing. Otherwise there is nothing in workplace regulations or in the product safety standard that specifically requires keyboards or mice to be certified. On the other hand there is nothing that specifically excludes them either.

Q: The international community relies on Ecma Standard - 383 Measuring the Energy Consumption of Personal Computing Devices, for establishing typical energy consumption of IT equipment, and the US uses ENERGY STAR V5.2. What is the difference between how these two treat testing of the Idle mode.
A: Ecma (formerly European Computer Manufacturers Association) International Std 383 recognizes the differences in how desktop and notebook computers are tested in idle, and with collaboration with the EPA, incorporated "Long Idle State" and "Short Idle State" into 383. Currently the only difference between Ecma-383 and ENERGY STAR V5.2 idle state testing is how the Hard Disk Drive is treated. Ecma 383 assumes the HDD is spinning in the short idle state, but might not be spinning in the long idle mode. ENERGY STAR requires the HDD to be spinning in both modes. Since the EPA helped create the Ecma 383 standard, it is suspected that the ENERGY STAR Version 6.0 will incorporate this approach to testing of Idle state, with the added motivation that HDD spin-down lowers idle power, thereby lowering the typical electricity consumption.

Q: Are devices certified to UL61010-1 prior to January 1, 2010 required to be certified to UL61010-1 2nd edition?
A: Product safety certification for health care & other laboratory equipment continues to evolve. As you indicated, on January 1, 2010, all new products and alternate constructions of listed or recognized products were required to be evaluated to UL 61010-1 2nd Edition.
The Second Edition combines UL 61010A-1 for laboratory equipment, UL 61010B-1 for test and measurement equipment and UL 61010C-1 for process control equipment into a single standard.
On January 1, 2014, UL 61010A-1, UL 61010B-1 & UL 61010C-1 will be withdrawn, and at that time, all listed and recognized products must comply with UL 61010-1 2nd Edition.
Visit our Blog for more on this subject.

Q: What is the difference between a Listed component and a Recognized component?
A: Listed components are complete in construction and can be used without further design concerns. This means that during the certification of the component itself, the agency was able to either simulate the worst-case application (therefore covering all possible applications) or determine that the performance of that component regarding safety is independent of the end-application. For example, a listed power supply will always have the same I/O ratings and safety isolation, regardless of how it is employed. Recognized components, on the other hand, are incomplete in construction and further consideration must be given to the design employing that component. Read more on this subject at our Compliance Today Blog.

Q: We are considering having a HALT evaluation performed. Just what tests are performed for this evaluation?
A: The HALT Stress Test purpose is to "stimulate" failures as opposed to "simulating" an operating environment. Thus the EUT has to be exposed to conditions outside of normal limits to discover potential design or process weaknesses (2 to 5 days for most products).

To do this the HALT process will expose the EUT to:
1.Thermal Step Stress
    - Cold Step Stress
    - Hot Step Stress
2. Vibration Step Stress
3. Rapid Thermal Transits
4. Combined Environment

Q: My product is powered from an internal rechargeable battery. The product will be used by tradesmen in their work. I will supply an "off the shelf" plug in mains charger from another company. It will already have an NRTL listing. Is there a legal requirement for my battery powered product to be NRTL listed?
A: The answer is maybe. Sorry, this is one of those situations that is not super clear in the OSHA requirements.
The primary OSHA requirement that electrical equipment used in the workplace shall be NRTL listed is contained in 29 CFR Part 1910.303. The full text may be read here. A complete list of references to OSHA standards that require NRTL Approval may be seen here. At the bottom of this page is a definition for the term "Acceptable" as it is used in OSHA documents.
Unfortunately these requirements do not make a distinction between a mains-connected device and one that is battery-powered but recharged from a mains-connected device. Many safety standards, in fact, identify batteries as a potential source of hazard and include requirements for battery-operated products.
One example is the standard for safety of information technology equipment, UL 60950-1, which has specific requirements that address safety concerns with overcharging and excessive discharging of batteries. The primary safety concern is with respect to fire or energy discharge rather than with electrical shock. Of particular concern are products that are transportable or products that use lithium-based batteries.
So to answer your question, if the applicable safety standard has requirements for battery powered equipment then it is quite likely that the OSHA rule will be interpreted to apply to your device. The best bet may be to have the product evaluated, tested and certified to comply with the applicable safety standard so that no question is raised once the product is deployed.

Q: Are there routing methods for cabling that would help reduce EMI emissions?
A: Use wiring harnesses and wire ties when routing cables inside a box. EMI pickup on I/O cables is a major contributor to overall radiated noise. Route cables along the sides of the box and away from high frequency components and switching power supplies.

Q: It is my understanding that IT products to be sold in Europe must show compliance to the 2nd edition of EN60950-1. Are units previously tested to the 1st edition still acceptable?
A: Unfortunately, no, products previously tested to EN60950-1 1st edition will NOT be grandfathered.
And, all IT products MUST show compliance to EN60950-1 2nd edition starting Dec. 1, 2010.
Good news: Changes in the 2nd edition are not extreme, but a re-evaluation of a product to a new version of a standard is not a quick undertaking. In general, the newer version adds consistency through clarification of either terminology or test methodology.

Q: We wish to certify an access router for FCC registration. FCC part 68 may apply. There are some requirements regarding robustness against surges. Do these requirements apply on all the interfaces or only the interfaces potentially directly connected to external lines?
A: The Lighting Surge requirements from TIA-968 involve both Telecom ports as well as other ports on the unit under test. "Non-approved ports" are all ports on the equipment under test that would not connect to certified telecom equipment at the remote end (i.e. Ethernet, Serial, etc.).

Q: How do I know if an EMC standard is suitable for the EU marketplace?
A: There are three types of EMC standards - Basic, Generic and Product or Product Family specific. Basic standards, mostly in the IEC/EN 61000-4 series and the CISPR16 series, only give test methods. Generic standards apply to products for which there is no specific Product or Product Family standard and set minimum requirements compatible to existing Product and Product Family standards, unless CENELEC TC210 has posted a technical justification for any requirement easing.
It is important that the EMC standard addresses all aspects, ie., radio-frequency, emissions and immunity, otherwise compliance to several standards may be necessary.

Q: Is it true that if we certify a module for Japanese use – i.e. it has a Telec certification - then no further Telec activity is required for the end device which houses the module? Also, is the Japanese process the same as in the US, ie. do we need to place the Telec certification number on the end device as well as the module?
A: Yes, it is true, once a module has Telec certification, no further Telec activity is required for the module. You just place the certification number on the certified module only, for a module certified for Japanese use.

Q: Why does the test engineer cut my product’s cabling for MIL-STD testing?
A: In most cases, MIL-STD testing requires the test engineer to couple RF stimulus into the product’s ports by means of capacitive and inductive coupling methods to determine the product’s ability to withstand adverse conditions. Often, the MIL spec requires the test engineer to splice in coupling transformers or coupling capacitors onto the shield of the cable for injection purposes. We recommend to all of our MIL-STD customers to supply duplicate cabling, when needed, with one set to be typical installation lengths and the other set to be used for splicing.

Q: Somebody in my company says that the FCC logo is not required or necessary for Class-A equipment, only for Class-B equipment.  Any idea?
A: That is correct. The FCC logo is for Class B products only. It’s not appropriate for Class A products.
1) However, Class A product is still required to display the following statement on the product:
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.
2) For a Class A digital device or peripheral, the instructions furnished to the user shall include the following or similar statement, placed in a prominent location in the text of the manual:
Note: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense.

Q: If I am doing HazLoc testing, why do I need to do Normal Location testing?
A: It is done for a couple of reasons:
1. The hazardous location standards require compliance to applicable normal location standards.
2. The normal location standards address hazards that are not addressed by the hazardous location standards.
For example, leakage current, mains energy discharge, and mechanical hazards may not necessarily have an effect on compliance with hazardous location requirements, but they present hazards to the user of the equipment in the form of electric shock, electric energy, and physical injury. Further, for some equipment, there are local requirements regarding connection to the supply system. This is not addressed by the hazardous location standards.

Q: I purchased a new board from an OEM that already has a CE mark on the board, to put it in my system which already has a CE mark as well. Do I need to retest my system again?
A: It is a common misconception that CE+CE=CE. If the change aims to modify the end product’s original performance and purpose, an assessment should be performed to determine if the directive’s essential requirements are still being met. If the assessment leads to the conclusion that the nature of the hazard or the level of the risk has increased, the modified product should normally be considered as a new product. Therefore, reevaluation is necessary.

Q: Is NEBS Airborne Contaminants testing still required if the GR-63-CORE fan filter requirements are met?
A: Yes. Hygroscopic dust particles are finer than the air filters in central offices and fan filters in equipment can keep out.
Conventional fan filters also do not have any effect on the gas concentrations in Mixed Flow Gas testing.

Q: What is meant in vibration standards when it is specified as: p-p; 0-pk; g’s; grms; g^2/Hz; dB/oct; Oct/min?
A: In the context of vibration testing:
p-p (peak to peak): Is a notation used in Sine Vibration and is usually associated with displacement.
0-pk (0-peak): Is a notation used in Sine Vibration and is usually associated with velocity and acceleration although some standards, such as MIL-STD-167-1, do use this for displacement.
g’s: Is a notation used in Sine Vibration and is abbreviation for Acceleration. One g = 9.81 m/s^2.
g^2/Hz: Is a notation used in Random Vibration. It is also know as Acceleration Spectral Density (ASD) or Power Spectral Density (PSD). ASD values are used to define the frequency/amplitude breakpoints of a random vibration profile.
grms: Is a notation used in Random Vibration. The grms is used to quantify the total power of a random vibration. The grms is equal to the square root of the area under the curve.
dB/oct decibels/Octave: This is used in both sine and random vibration profiles. It is used to define slopes in vibration profiles.
Oct/min Octaves/minute: Is usually used in Sine or Sine-on-Random Vibration to define the sweep rate of the sine tone. It is sometimes used in Random-on-Random Vibration to define the sweep rates of the random narrow bands. This type of profile is usually used for tracked vehicles.

Q: I am curious what other laboratories are doing regarding ferrites. When performing radiated emissions testing to EN55022 (2006), do you allow the use of ferrites on the I/O cables outside the test space (i.e. under the floor of a raised OATS or a semi-anechoic chamber)?
A: Ferrites may be used as long as they do not become part of the EUT, i.e. they should only be used on the support equipment side. Also there is some ongoing debate that having ferrites on the support side may potentially change the characteristics of the interface.
In other words ferrites may be used on the support equipment side of the test setup as long as they don’t change the I/O line characteristics.

Q: I am familiar with HALT and HASS testing, but what is HASA?
A: Here is a quick primer on HALT/HASS/HASA:
HALT – Stands for Highly Accelerated Life Testing
HASS – Stands for Highly Accelerated Stress Screening
HASA – Stands for Highly Accelerated Stress Audit. It is the same as HASS, but run on a sample basis only. It is generally performed when all HASS issues have been resolved.

Q: Since the U.S. Government Accountability Office found evidence of abuse in the Energy Star self-certification program, will all Energy Star-marked products be required to be tested at an independent 3rd party laboratory now?
A: EPA and DOE announced, effective this fall, that all manufacturers must submit test results from an approved, accredited lab for any product seeking the ENERGY STAR
label. Testing in an accredited lab is presently required for certain product categories, but the new process will extend the requirement to each of the more than 60 eligible product categories under the ENERGY STAR program.

Q: Doesn't the Automotive Directive require conformity to EN55025? What are the corresponding requirements in the US, if any?
A: In US, SAE is primarily responsible for automotive standards, not the FCC. The closest to EN55025 for EMC is SAE J1445: 2006.
In addition, the 3 major U.S. automotive manufacturers have their own standards for EMC, which are based on EN55025 for most part. But these standards are not mandatory. EMC automotive standards are still voluntary, despite issues with Toyota and other vehicles electrical systems.

Q: Is ANSI C37.90.1 (Surge Withstand Capability Tests for Relays and Relay Systems Associated with Electric Power Apparatus ) equivalent to the IEEE standard? My customer is looking to the 2002 version, so that’s a plus. His only question is, is there a way he could be exempt if he is low voltage?
A: IEEE and ANSI sometimes each take various responsibilities in the same standard.  Within IEEE C37.90.1-2002, previous versions of the standard are referred to as ANSI/IEEE C37.90.1.  The prefix ANSI and IEEE are used interchangeably in referring to C37.90.1.  MET tests to the current version of this standard, which is the 2002 version.
IEEE C37.90.1 is applicable to relays and relay systems. The tests described in IEEE C37.90.1 are to be applied to any part of the relay system that can be exposed to conducted or coupled transients under normal installed operating conditions.
Testing to IEEE C37.90.1 is not a regulatory requirement. It is sometimes a requirement of power utilities and similar companies. The acceptability of any exemptions claimed by the manufacturer of the equipment under test would be the responsibility of the purchasing company.

Q: Why aren't European and US wireless standards harmonized?
A: The short answer is power, frequency and test methodology. There are significant differences in radiated power requirements and operating voltages - 120V / 60Hz for US and 240V/ 50 Hz for Europe. Europe addresses immunity, whereas in the US it is not as much a concern.
Even basic test criteria of positioning the EUT differ. US standards require 0.8 meter above the ground plane devices for unlicensed devices, 1 meter for licensed devices. European standards require 1.5 meters for all devices.

Q: What determines whether a product safety certification will need two or four follow up inspections per year?
A: Starting in 2003, OSHA changed its policy, reducing follow up inspections from four to two for most products.  Four follow up inspections are still required for certain equipment and scenarios:

  • Products intended for use in hazardous locations
  • Manufacturer has a history of poor quality control or mark misuse
  • Facility is in a region where counterfeiting occurs regularly
  • There are safety concerns for the product

Q: What is the difference between NEBS Level 1, Level 2 & Level 3 testing?
A: Level 1 does not address operability.  It ensures that people and equipment hazards and network degradation are minimized.
Level 2 addresses equipment operability, but in a controlled environment. 
Level 3 is the most stringent level, meeting all the requirements of GR-63-CORE and GR-1089-CORE.

Q: With EMI, what is the difference between narrowband and broadband emissions?
A: Usually expressed in volts per meter (V/m), narrowband emissions include communication transmitters such as single-channel AM, FM, and SSB. Narrowband spurious emissions include harmonic outputs of local oscillators, signal generators, test equipment, and many other sources.
Usually expressed in volts per meter per MHz (V/m/MHz), broadband emissions are composed of narrow pulses having relatively short rise and fall times. Examples include unintentional emissions from electric switch contacts, thermostats, motor speed controls, ignition systems, voltage regulators, and pulse generators. They might also result from galactic and solar noise, and from radio frequency pulses associated with electrostatic discharge.

Q: How often must a product be retested for continuing compliance to Part 68?
A: TCBs are required annually to perform post-market surveillance on at least 2% of equipment that has been certified by that TCB.  So, potentially, a continued compliance testing program would be performed no more than once annually.

Q: We worked with another lab a few weeks ago and the NSA for their radiated emissions chamber was much larger than +/-4dB and they will use the NSA numbers as correction factors to correct the measured radiated emissions results. Is this allowed by applicable standards?
A: Applicable standards here are ANSI C63.4 and CISPR 16. CISPR 16-1-4 clearly states not to use the differences between measured NSA and theoretical NSA as correction factors. The only recommendation per CISPR 16-1-4 is to investigate and bring the measured NSA within ±4 dB.
From the standard:
"The deviation between a measured NSA value and theoretical value shall not be used as a correction for a measured EUT field strength. This procedure shall be used only for validating a test site."

What does the CE marking mean?
A: The CE Marking, stands for Conformité Européenne (European Conformity). It certifies that a specific product has met European Union health, safety and/or environmental requirements. The CE Marking is only suitable for products destined for the European Union where there is a legal structure to support necessary actions in the event of human injury. Products with the CE Marking may be self- certified depending on the directive, and European law does not require regular follow-up inspections of the certified product. However, a manufacturer must be prepared to provide proof of compliance if the safety of a product is ever questioned.
For the United States, OSHA dictates that all equipment used in a workplace must carry a listing or label from an OSHA-approved NRTL. If a product only carries the CE marking, an NRTL should be contracted to perform a field labeling investigation to ensure that the equipment meets the appropriate US safety standards. All NRTL listed products must also undergo periodic follow-up inspections to ensure maintained compliance.

Q: I am hearing that there has been some new thinking on Verizon's part for its Thermal Modeling Simulation and Testing (VZ-TPR-9208) requirements. If so, what level of product modification triggers a new round of thermal modeling evaluation?
A: Verizon has modified its technical purchase requirements (TPR) for Thermal Modeling Simulation as well as its TPR for printed board aassemblies manufactured with lead-free solder. As far as thermal modeling, any change where the air flow fluctuates greater than 10% would necessitate new evaluation. MET has prepared a summary about the changes of both of these Verizon TPRs.

Q: Does the UL standard require that the computer keyboard be fused?
A: The applicable standard UL 60950-1 does not specify a fuse or other over current device unless through evaluation and testing of the product it is determined necessary in order to reduce the risk of fire.

Q: If my product is powered by a compliant AC/DC power supply, can I skip some of the AC power immunity tests in the final product testing (ie. dips, interruptions, burst, surge, and conducted RF immunity)? Or do I need to "redo" all of this testing in the final compliance evaluation?
A: Even if you are sourcing a compliant power supply from an OEM, if you are packaging it together with your product, all power related tests will have to be performed.  By definition, the EUT is comprised of the system of components being certified which will include the power supply, so testing is required to see how the system performs against the criteria as a whole.  If you were to market your product in a standalone sense, then you would not have to perform the power tests but at the same time, could not guarantee your product’s compliance with those tests with whatever power supply the end user decides to use.  For this reason, most vendors will choose to include a power supply and test it with their product to be able to guarantee compliance for the package they market.

Q: Is the lamp of a luminaire (IEC 60598-1), or a piece of test and measurement equipment (IEC / UL 61010-1) considered a "critical component"? For example, a typical double capped, G13 base, visible light, cool white spectrum linear fluorescent tube.
A: If this is a passive lamp, if it emits only visible light, and if it is otherwise a generic item, then it would not likely be considered safety critical.

Q: What certification is necessary for a bluetooth gadget that is designed to be operated with smartphones in the USA market? The gadget also includes an isolated piezoceramic transducer that is used underwater. I am aware of the FCC regulations, however, I am not sure about the safety certifications (UL?). I would be grateful if you could explain what safety certificates are manatory in this case.
A: Not knowing the actual purpose of the device makes it difficult to provide an answer with 100% confidence so… As for mandatory safety certification, that is probably going to be driven by the customer (distributor or retail outlet rather than a user) for a device like this device. Assuming it is powered by a conventional Li-Ion battery like any other small BT device, there is no specific workplace regulation so OSHA would not mandate safety certification. If for marketing reasons you volunteer to have this safety certified the first standard that comes to mind is UL 60950-1; however, it may be different depending on the actual purpose of the device.

Q: What are the differences in the ESD test procedures according to JEDEC versus MIL standards?
A: JEDEC focusses on global standards for microelectronics.  The US Military writes standards for every device they use, from microelectronics up to full systems.  Perhaps the question was intended to mean, “What is the main difference between the test methods used for ESD testing of semiconductor devices compared to testing of complete electronic subassemblies?”  Semiconductor devices are tested with an ESD generator that resembles a drill press.  It is constructed of a probe stand, test fixture, and test leads to accommodate various device packages.  Testing of semiconductors is often performed with no power applied to the device under test.  Electronic subassemblies are tested with an ESD generator that resembles a handheld gun.  Testing of subassemblies is performed with the subassembly setup and operating in a manner typical of actual use.  Standard test levels for semiconductors are much lower than test levels required for subassemblies.

Q: Dear Pat, is the EN62368 stantard going to replace the 61010 for mantenance and repetitive task testing in medical enviroment?
A: EN 62368 is a standard for safety of information technology equipment and audio/video equipment; it is not a medical device standard. EN 62368 will replace EN 60950-1 and EN 60065-1 at some time in the future but it has no impact on EN 61010-1.

Q: Are USB connectors always treated as SELV circuits in agency evaluations? I'm developing a motor control device and it will have a USB connector to allow users to change settings & interface with the device. I'm just wondering if SELV requirements will come into play in my device
A: USB connections are ubiquitous and taken for granted by users so they are always treated as SELV circuits.

Q: Are products of the fundemental carrier (i.e 2nd, 3rd, etc harmonics) excluded from having to meet the applicible EN55022 Class A or Class B radiated emissions limits? If so is there an authorative reference I can point to that specificaly states this?
A: EN55022 is meant to be applied to IT products, is this device a radio/ wireless product i.e. intentional transmitter?

Q: Do all 120 VAC devices require CSA certification for resale in Canada? I am interested in importing a charger into Canada from China for resale. I have found three manufacturers but none of them have a CSA certified charger. All have CE certification and one also has UL certification (without a 'c' beside the UL logo indicating CSA compliance). The charger is a 'wall wort' power supply similar to a cell phone charger with 12 VDC power output.
A: The answer is essentially Yes. Different provinces of Canada will have different codes and regulations on this issue but will expect it to be approved for its use. For Ontario, see: For Quebec, see: The first line states “In the province of Quebec, the selling or renting of electrical equipment that has not been approved is prohibited. All electrical equipment used in an electrical installation or intended to consume energy from such an installation shall be approved for the use for which it is intended.” The other provinces also have similar requirements.

Q: Can you cite the Canadian Electrical Code rule requiring ELV outdoor only lighting to be CSA approved?
A: Number 1. 2-024 Use of approved equipment (see Appendix A) Electrical equipment used in electrical installations within the jurisdiction of the inspection department shall be approved and shall be of a kind or type and rating approved for the specific purpose for which it is to be employed. Number 2. Approved (as applied to electrical equipment) — (a) equipment that has been certified by a certification organization accredited by the Standards Council of Canada in accordance with the requirements of (i) CSA standards; or (ii) other recognized documents, where such CSA standards do not exist or are not applicable; or (b) equipment that conforms to the requirements of the regulatory authority (see Appendix B). Number 3. Extra-low-voltage lighting systems 30-1200 Rules for extra-low-voltage lighting systems Rules 30-1202 to 30-1208 apply to extra-low-voltage lighting systems. 30-1202 Sources of supply (1) Extra-low-voltage lighting systems shall be supplied from branch circuits operating at not more than 150 volts-to-ground. (2) The extra-low-voltage portion of the system shall be supplied from the secondary of an isolating transformer approved for the purpose having no direct electrical connection between the primary and secondary windings. (3) The extra-low-voltage portion of the system shall not be grounded. 30-1204 Installation of landscape lighting systems (1) Flexible cord shall be permitted to be used on the secondary side of the transformer and be permitted to be secured to structural members and run through holes. (2) Electrical connections shall be permitted to be made without an enclosure where not exposed to mechanical damage.

Q: I have a medical product which is operating at 100-240VAC. Also it has internal battery which charges when EUT operates in AC mains. Please let me know do i need to do EMC test like RE,RS,ESD & PFMF tests in battery mode also. If yes which standard is asking for it.
A: I believe the most suitable standard would IEC 60601-1-2, and testing would have to done both in battery and AC modes.

Q: If my wall adapter is UL listed, is it necessary to have the device it powers and the batteries also UL Listed?
A: The answer is maybe. Sorry, this is one of those situations that is not super clear in the OSHA standards. Please read on.

The primary OSHA requirement that electrical equipment used in the workplace shall be NRTL listed is contained in 29 CFR Part 1910.303. The full text may be read here. A complete list of references to OSHA standards that require NRTL Approval may be seen here. At the bottom of this page is a definition for the term “Acceptable” as it is used in OSHA documents. 

Unfortunately these requirements do not make a distinction between a mains-connected device and one that is battery-powered but recharged from a mains-connected device. Many safety standards, in fact, identify batteries as a potential source of hazard and include requirements for battery-operated products.

One example is the standard for safety of information technology equipment, UL 60950-1, which has specific requirements that address safety concerns with overcharging and excessive discharging of batteries. The primary safety concern is with respect to fire or energy discharge rather than with electrical shock. Of particular concern are products that are transportable or products that use lithium-based batteries. 

So to answer your question, if the applicable safety standard has requirements for battery powered equipment then it is quite likely that the OSHA rule will be interpreted to apply to your device. The best bet may be to have the product evaluated, tested and certified to comply with the applicable safety standard so that no question is raised once the product is deployed.

You might try contacting OSHA and requesting an interpretation of your particular situation directly. You can start here. You might also wish to contact someone with the OSHA NRTL Program by calling (202) 693-2110 or emailing at This phone number and email address were current as of November 30, 2010 and were obtained from this webpage

Finally, it may be important for you to understand that the OSHA requirement is directed at employers, not users, vendors or manufactures. The onus to comply with any OSHA requirement is on the employer. It is up to the employer to make sure his employees are able to work in a safe environment as defined by OSHA.

We are available to assist you further. Contact us at one of the locations given on our website and we will be happy to review your scenario further.

Q: Hi Pat, Does a battery-powered device need to be certified by the CSA or similar group to be sold in Canada? We have a CE mark already. Is a battery-operated device considered "electrical"? (It only operates with 2 AA batteries, and does not connect to a charger or other sort of adaptor at all.) Also, for products that are electrical, is the CSA mark required to be displayed on the unit or adaptor, or both? Thank you for your help.
A: We are unaware of a specific regulation for battery powered products; however, compliance to a safety standard may be required regardless of the power source depending on the type of product. For example, battery operated smoke detectors are expected to be certified to a safety standard despite the power source since it is a life safety device. Battery powered medical devices are another example of a product that is expected to be certified to a safety standard. 

So even if the product appears harmless because of its power source, if it is relied upon for life or property protection, or if it has the potential of causing harm through some other hazard such as laser light emission, then it will likely be required to be certified. Another factor to consider is whether the competition is certified or not and also what the buyer might expect.

As to which part should bear the safety agency mark, that’ll depend on the specific type of product as mentioned above. A battery powered medical device would have a mark and so would its external power supply, for example.

Q: Pat, You state below: A: USB connections are ubiquitous and taken for granted by users so they are always treated as SELV circuits. Do customer connections on a SELV PWB (SELV components like USB, ethernet, phone connectors or other type of comm ports) need to be NRTL Listed or Recognized components?
A: To our knowledge there is no written law or regulation that specifically requires certification of USB-powered devices. Ultimately it may be necessary to seek legal advice as to your liability, however, we offer the following information for your consideration…In fact – and this is not an endorsement of this practice by MET – there are many, many examples of both certified and uncertified USB-powered products on the market being sold and bought from reading lights to personal fans to mice and keyboards. In fact most cell phones are rechargeable from a USB port but few cell phones are safety certified.Some considerations to be made include What does the buyer expect?, Does the retailer require it?, Does the device incorporate any functions or features that might add a hazard that is not electrical in nature such as laser emission or heat generation or cutting parts?

Q: Dear sir I had a question about "ac adaptor power supply" which used with notebook or tablet. does "ac adaptor power supply" is tested according to IEC60950-1 independent? if yes , for providing normal load condition which action is used? DOES it install with dummy load (connect the resistive load to output and set it according to output rated votage and current)? because in many case when the ac adaptor power supply connect to load as above , after few hours the voltage is reduced, I want to know according to IEC60950-1 IS that acceptable or not
IEC 60950-1 does not specifically address the voltage stability of power supplies.  It is therefore assumed to be left up to the manufacturer and/or their customer’s to determine if such instability is acceptable for use with their products

Q: Hi Pat, Can you give me details of the "Harmonics tests will be added under Section 5.5.6 of the C12.20 standard in the next revision" please?
A: Harmonics tests have not been finalized yet, but as proposed they are similar to IR46. 

Q: We are certifying a Bluetooth enabled personal sound amplifier (actually our second product) and our test lab is telling us we need additional testing because FCC now requires the power adapter (FCC certified already) to be tested again because it is part of the kit we provide. Thoughts?
A: I do agree with your lab’s opinion. It will need to be tested.

Q: We have just installed a battery charger for a 48VDC battery. It charges the batteries at a rate up to 50 amps. The charger plugs into a receptacle and it just sits on the floor. We just had an inspection of this installation and he said the charger must be UL listed which is not. We have been told in the past that equipment that is portable and plugs into a receptacle does not need a UL listing. Can you tell me the rules for this? This installation is in Tennessee, if that makes a difference, but we would like to know the requirement for all states.
A: If an electrical device, whether cord and plug connected or hardwired, is used in a business then OSHA regulations require such equipment to be listed by a NRTL. Additionally local authorities having jurisdiction (AHJs) such as electrical inspection authorities  or building inspection authorities may have local regulations to comply with that contain similar requirements. Finally building owners or their insurers may have similar requirements, despite means of connection to a mains circuit. We recommend that you ask the local AHJ to identify to you  regulation they are using to pass judgment.

Q: Will I need CSA approval for a 12 volt LED system consisting of a Rayovac (23A) battery a single on/off switch and 6 inches of LED lights to aluminate cast acrylic (plexi-glass) ornaments to sell?
A: There are standards that cover luminaires whether mains or battery powered but as far as requirements to certify, that is uncertain for your particular device. It is best to check with your importer or retailer in Canada to find out what the requirements may be for your particular device. You may also want to check some competitors to see what they are doing. Our suggestion is to have it certified.


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