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Questions tagged [ul]

UL (Underwriters Laboratories) is a global independent company that performs safety consulting and certification. They publish many safety standards for electrical and electronic products and the UL mark on equipment indicates it has passed their tests for electrical safety.

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Is UL 508A listing required for a portable piece of equipment connected to mains power by means of a power cord with plug & receptacle?

We've had clients install things like portable chillers in this fashion for years & have never been required to have the chiller listed because it's not permanently powered. Now we have a local ...
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62 views

Unmanned laser need to be UL Approved [closed]

I'm going to build a mobile unmanned imitation rock that has a green laser that is going to come on automatically every 15 minutes after dark and it will sweep 90 degrees. Will I need to have it ...
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93 views

Can transformerless power supplies be UL/CSA certified and is there any specific standard they must meet?

I am trying to bias a linear optocoupler on the AC mains side of a circuit, in order to transfer analog information to the secondary side of the circuit. I have designed the following capacitive power ...
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56 views

Does anyone know the UL standard related to resistors and isolation on AC mains?

I have a circuit that is attempting to measure AC line voltage 120-240V but I was told by the certification test lab that my voltage divider resistors would require an expensive 3 week soak test. The ...
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103 views

Is UL approval only required for the power supply?

Suppose a mains powered device has a PSU in the assembly that has a detachable cable to the mains. Is it just the PSU that needs to be UL approved/compliant? Is the whole device therefore UL-compliant ...
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27 views

Definition of Field Wiring Terminals as in UL 499

I'm wondering if anyone can tell me where I can find the definition for "field wiring terminals" as referenced in UL 499 "Standard for Safety Electric Heating Appliances" table 27.1 "Minimum ...
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1answer
109 views

UL 840 clearances

The table 8.1 in UL840 doesn't consider clearances for voltages less than 50V (for example). I have to use a clearance of 0.2 mm on the PCB for the case of overvoltage category 1 and pollution degree ...
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52 views

UL Listed Item - fused, but plug rated higher than wiring

We are installing an item and have some concerns. The supplier is claiming we will void the UL listing and warranty but the current configuration seems unsafe. I am curious if the following would be ...
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35 views

Reference material for mains-interfacing circuit safety

I've designed a simple switch/timer circuit for the following environment: Residential installation for North America (technically only for Canada) Single-phase 120Vac Current of switched output ...
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245 views

Creepage distance over pcb

How to measure creepage distance over pcb ? Is creepage and clearance distance measure by pbc layout or soldering?
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2answers
746 views

IEC vs. UL current rating

I was doing a search on Digikey for some power entry connectors and noticed that many of the connectors are rated 10A by IEC standards and 15A by UL standards. Why is there such a large difference ...
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51 views

Electric Tester light up on secondary side of Ground

I have assembled a PCB, which takes mains input 240VAC line and Neutral (my system enclosed in plastic case , so no ground/earth is provided) , and it use on board SMPS module(https://www.meanwell.com/...
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Compliance Testing Strategies

How do people / companies deal with compliance testing (CE, UL, FCC, etc.) what I would call "platform-oriented and modular" products? The idea being that a family of products might exist, where a ...
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174 views

UL/IEC-60950 Standard Question

One of the requirements I need for a device is to meet the UL/IEC-60950 standard. On the companies website I am looking at it mentions that "products are assembled and tested in company’s own ISO9001:...
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42 views

Where do hi-pot multipliers come from?

I am researching AC vs. DC hi-pot testing. According to UL 508 and IEEE 421.3, a hi-pot test should, among other things, subject the unit under test to 1000 volts plus twice the rated voltage of the ...
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109 views

How to deal with non UL DCDC converters?

We have a product, and we're trying to get it MET marked for export from the UK to the US. It uses an APD S10 converter [datasheet] to generate +-250V rails from a 12V supply. It's an isolated ...
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97 views

If a device has UR sign on the label, it called it is UL approved or not?

In the data sheet for a device there is a code to indicate it is UL approved. on the label this code not there but there is a sign UR. IS UR also can called it is UL approved? or UL approved not just ...
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889 views

What is the general rule of thumb regarding UL's creepage clearance regulation?

I've read a whole bunch of material but I'm still quite confused regarding creepage clearance, specifically: How to calculate the minimal clearance on a PCB board? How to calculate the width of the ...
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1answer
186 views

USB power pack in wearable electronics: Is it safe?

I'm developing a wearable electronics product that runs on batteries. I would like to use a USB power pack like this as the battery, but I need to make sure it's not a fire hazard because it's going ...
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2answers
1k views

What cable standard is needed for UL94V-0 device

I'm designing a device that has UL94V-0 rated plastic parts. So far so good. But there are also a number of cables inside the enclosure and cables use different ratings.. What would match UL94V-0 in ...
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4answers
274 views

How to know or find if a potentiometer is UL certified

We have selected a 100kohm potentiometer to dim LED's that are connected to a class 2 power supply. However, according to UL; all selected parts need to be UL recognized for the device to be UL ...
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1answer
63 views

Need advice on new device regulatory requirements

I have designed a product (device) that runs on 12 VDC (similar to a laptop). It is AC powered using a (table top), detachable switching power supply 100 VAC to 240 VAC, 50-60 Hz, again exactly like a ...
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212 views

What tests, certifications and labels do I need on my new electronic gadget? [duplicate]

I have designed a VERY basic lighting gadget -- it's basically a flashlight. It turns on and off with a switch and is powered by a rechargeable Lithium Ion Battery via USB cable. It consists of LED's ...
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78 views

Safety shields for power supply DC output bus bars

I have seen a variety of optional or included features with power supplies that the manufacturer calls a safety shield. In some cases it is just a 3 sided piece of metal - the back and bottom remain ...
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127 views

UL fire safety clearance requirement

The DUT is a relatively high-power LED driver driven by a SELV high-power +24VDC supply. It'll drive LED voltages up to 55V by specification. So everything is considered safe as far voltages are ...
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918 views

UL procedure of PCB Design

I Need to design a Energy meter ( Single phase 240 Vac, 0.4 mA ) , its a industrial product with enclosure of IP 67. I need to design PCB for this product as per UL. I am new to UL procedure so please ...
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1k views

Electronics System Standards Compliance: Certification, Testing & Verification

Please note: this question has to do with the technical compliance aspects of the consumer electronics indsutry, and as such, I believe is within scope for this site. This question is about compliance,...
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1answer
1k views

US wire color coding clarification

I was buying a AC powered RV/Marine cord reel from outside USA. The cord has 2 lines, 1 neutral and 1 ground. The colors of the cores in the cord are red, yellow, blue and green. I need to use this ...
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115 views

Circuit Testing, Verification & Certification Standards for Biomedical Devices

Please note: I would have posted this question on HealthIT.SE but they are apparently now closed for business, and I believe this site is the next most appropriate place to ask this. I believe this ...
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2answers
161 views

If I incorporate a UL/NRTL listed power supply in our product, must we re-test?

We are building a product. It's a bench-top electrical testing thing, similar to a Keithley DMM or an oscilloscope in that it's something engineers would use at companies for testing stuff and ...
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2answers
133 views

High dielectric strength temperature sensor (2500V)

I am trying to measure the temperature on a heatsink that is at Earth ground potential, while my circuit ground is at line potential. Typically I would use something like the Microchip MCP9700 in a ...
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2answers
361 views

Getting UL certification for neon signs

I make neon lights and have been for 10years on my own and just recently found out that I could get in alot of trouble for not having my signs UL certification done. I want to make it right and want ...
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298 views

Mains isolation is mandatory for UL/CE/CSA compliance and other certification?

I have a design with a non user accesible low voltage section. Is mandatory to do mains isolation to pass succesfully UL/CE/CSA despite my low voltage section is not accesible for user?
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119 views

UL listing of a fan

An electrical Inspector has stated he cannot accept our fan for use in an industrial diesel Exhaust removal system since the entire fan does not show a UL listing number. We have tried to explain that ...
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986 views

UL listing for USB device with battery, detachable cord and transformer

I want to import a device (for resale) that comprises the following components: Wall transformer (already UL listed), USB wire, LED light assembly, rechargeable battery (already listed). The ...
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1k views

What are UL Contact Ratings in a Relay Datasheet?

These UL contact ratings are listed in the datasheet for a Tyco relay: T90 Series, 30A PCB Relay. (Note: the link will ask you to download the PDF, as do most Tyco PDF links) The contact life is ...
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2answers
2k views

Transient voltage suppression diode not doing its job

I have a circuit which works on 21V DC and draws 3A maximum current. I need to get it tested to IEC 61000-4-4 and 61000-4-5 standards which are surge immunity tests. I use a UL certified switch mode ...
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17k views

UL/CE/CSA certification for low voltage electronics/LED product?

I am working on a fairly simple LED product that would use an external power supply (12V). Certain configurations of the product may require more than 100W. I could also configure the product to use ...
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2answers
1k views

How do variable-frequency drives pass UL 508c failure of components testing?

Every 480V variable frequency drive I've had the pleasure of dissecting has had two DC capacitors in series across its DC bus, each rated for ~400VDC. UL 508c testing as executed on one of my recent ...
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1answer
184 views

Bringing compiled device to market (and how to power)

(Preemptive apology if this is the wrong place to ask; pointers to the right place appreciated) I've thrown together a device using a Raspberry-pi, touchscreen (plugs into pi) and small monitor ...
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461 views

Can I sell a CSA approved product in the US at retail or over the internet?

I have a product that was designed to sell in the RV market. The RV industry does not require require UL per se, just a "recognized listing" which can be from a number of agencies including CSA (to ...
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522 views

Nationally Recognized Testing Laboratories or UL Certification necessary for USB device

I'd like to import a USB device similar to a mouse to the USA and Canada, does it need to be certified by Nationally Recognized Testing Laboratories (NRTL) or UL? Does it make a difference if the ...
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2answers
13k views

How to get UL approval for lamps and pendants

I'm a glass artist and designer and would like to make lamps and pendants. I'm told that I need UL approval for the electrical part. That is all the wiring etc. I know I can have an electrician who ...
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3answers
3k views

Why only 500VAC rating for this Y-capacitor?

I’ve been looking through a reference designs for an off-line flyback converters (this one by Texas Instruments and this one by Linear Technology). Both of them have a Y-capacitor between primary and ...
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1answer
1k views

What is the nature and history of UL capacitor recognition?

First, the background. I've been working on a grid-tied inverter design for some time now. General topology is: We've just completed UL listing our product under 508c, and the process was quite ...
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1answer
61 views

Wrong voltage sent to output

Using miniLab1008, I am trying to send 10V to my D/A OUT0 but it sends only 5V and when I send 5V, I get 2.5V. I am using the universal library example VOut01.c Is this a board problem? However using ...
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5answers
4k views

Do you need to UL Certified the enclosure with the board inside?

I want to use the RaspberryPI in an industrial environment that requires all devices have UL certification. The RaspberryPI board has UL certification but there is currently no enclosures that are ...
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7answers
82k views

Is UL approval required on all items sold in the USA

I have a spray tan machine which I wish to sell in the USA. I have had the machine tested by a CE test house. Do I have to have a UL approval as well?
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2k views

Are power supplies for USB drive enclosures required to have UL certification?

I bought a cheap USB hard drive enclosure off eBay. It turns out that the power supply has absolutely no electrical certifications for either the US or EU (no UL, CE marks). Is electrical ...
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7k views

Is it safe to use a DC power adapter that isn't UL Listed or CSA certified?

I picked up a 9V switching DC adapter from SparkFun a while back, but I've been hesitant to use it because it doesn't have any of the usual "safety" approvals that you normally see on power adapters (...