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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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,...
smeeb's user avatar
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18 votes
6 answers
122k 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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9 votes
8 answers
9k 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 (...
Owen Thomas's user avatar
9 votes
2 answers
3k 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 ...
mic's user avatar
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9 votes
1 answer
2k 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 ...
Stephen Collings's user avatar
7 votes
2 answers
17k 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 ...
varda's user avatar
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6 votes
3 answers
4k 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 ...
Nick Alexeev's user avatar
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6 votes
5 answers
6k 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 ...
Steven Smethurst's user avatar
6 votes
2 answers
278 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 ...
Daniel's user avatar
  • 6,188
5 votes
1 answer
219 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 ...
canterman's user avatar
5 votes
2 answers
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 ...
Stephen Collings's user avatar
4 votes
2 answers
1k views

What is this mains blade connector called?

I've asked around and can't find answers anywhere. I'm designing a PCB that connects to US-style mains blade connectors (that plug into the wall). I've found these here, but I need right angle ...
user3666672's user avatar
4 votes
2 answers
1k views

Does recommended creepage distance apply to copper planes under soldermasks?

I have a design that requires around 0.5mm of creepage distance between conductors. TI said in this video that "creepage is the shortest distance between two uninsulated conductors along the ...
Never's user avatar
  • 100
4 votes
2 answers
161 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 ...
smeeb's user avatar
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4 votes
2 answers
436 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 ...
Dave's user avatar
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3 votes
3 answers
385 views

Why are switchgears rated in specific capacities such as 63A, 100A, 125A and so on?

I am working in a consultant industry, wherein we get the switchgears from different OEMs. I wonder why the switchgears (including fuses and fuse-gears) and control gear assemblies are rated in the ...
DaSnipeKid's user avatar
3 votes
3 answers
3k 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 ...
user avatar
3 votes
3 answers
334 views

Finding manufacturer of product based on certifications

I really do not know where to ask this question so I am starting here. If you believe there is a better place let me know and I will gladly move post. I bought an induction cooktop from amazon and ...
Berchell's user avatar
3 votes
2 answers
8k 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 ...
pr871's user avatar
  • 1,167
3 votes
3 answers
151 views

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 ...
vicatcu's user avatar
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3 votes
3 answers
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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 ...
Saad's user avatar
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3 votes
1 answer
81 views

When does UL allow a user to access the a metal component connected to AC MAINS through a Y capacitor?

This is a 1kV SMPS design and it is considered a PRIMARY CIRCUIT by UL because it connects directly to 120V AC MAINS. It does not expose its 1kV output directly to the user, but uses the voltage ...
Derek Tables's user avatar
3 votes
2 answers
344 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 ...
Jason K.'s user avatar
  • 319
3 votes
2 answers
2k 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 ...
Bharav's user avatar
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3 votes
2 answers
249 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 ...
Kincaid Stringer's user avatar
2 votes
2 answers
4k 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 ...
Matt Cox's user avatar
  • 371
2 votes
1 answer
1k views

Do we have equivalent standards for all UL standards under IEC?

As per the image, it looks like there will be an alternative standard in IEC with respect to every UL standard?
nikhil valiveti's user avatar
2 votes
3 answers
351 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 ...
Jack B's user avatar
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2 votes
2 answers
1k 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 ...
Sparetech's user avatar
2 votes
1 answer
177 views

What assumptions are made by UL when they equate 30Vrms to 60Vdc for LVLE circuits?

UL defines Low Voltage Low Energy circuits as "A circuit involving an alternating current voltage of not more than 30 volts, rms (42.4 volts peak) or a direct current voltage of not more than 60 ...
jrive's user avatar
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2 votes
1 answer
650 views

UL grounding requirements for equipment powered by daisy-chained connections?

I am working on a device that will have AC power in and out connectors. The intent is to facilitate wiring multiple units to the same power circuit without having to use a multi-outlet strip. This ...
martin's's user avatar
  • 177
2 votes
1 answer
1k 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 ...
Haldun's user avatar
  • 21
2 votes
1 answer
142 views

UL certification and laser tag equipment

We are a 32+-year-old laser tag equipment company. We purchase parts overseas and assemble them in the US and have hundreds of installations all over the world. We have been told by 1 location that ...
Nancy Montague Rockhill's user avatar
1 vote
2 answers
911 views

Creepage distance over pcb

How to measure creepage distance over pcb ? Is creepage and clearance distance measure by pbc layout or soldering?
Vikas Verma's user avatar
1 vote
4 answers
842 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 ...
tooclosetosee's user avatar
1 vote
1 answer
155 views

When does an electrical product get an RU (Underwriters Laboratories) certified mark?

If you take an example of contactor, it can be used in residential, industrial, electric vehicle applications etc. Let's say the contactor has passed the UL standards corresponding to the industrial ...
nikhil valiveti's user avatar
1 vote
2 answers
879 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 ...
Tyler Kutz's user avatar
1 vote
3 answers
288 views

How to guarantee clearance/creepage on mains side of an optocoupler used for 230VAC zero-crossing detection?

Update: Added a diode to protect optocoupler LED As stated in several safety standards (UL 60950 or UL 60750 for example,) we have to guarantee a minimum clearance/creepage between signals of opposite ...
sgio's user avatar
  • 11
1 vote
1 answer
121 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 ...
nate's user avatar
  • 267
1 vote
2 answers
359 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?
Jairo Andres Velasco Romero's user avatar
1 vote
2 answers
649 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 ...
Nick's user avatar
  • 21
1 vote
1 answer
50 views

UL ratings and power supplies (DC transformer)

I read somewhere that if you sell a product that you plan to be UL certified, this means its power supply must be UL certified as well. This means that if you supply power via a transformer (external ...
user1584421's user avatar
  • 1,359
1 vote
1 answer
87 views

Connecting class 2 power supplies in parallel

I am looking to connect multiple rails in parallel to increase current of a class 2 power supply (UL1310). Each rail would have its own OCP (12V 8A). The problem I am having is that when talking to ...
Robbie Fennell's user avatar
1 vote
2 answers
97 views

Compliance of 2x female connectors with male pin breakaway from another brand

For a product similar to a 3D printer I'm connecting 5x small Nema 8 motors and ground cables through a small 26x connector. The connector is enclosed and cannot be accessed from the user. The motors ...
thomast's user avatar
  • 11
1 vote
1 answer
107 views

Understanding cable standards for low voltage conductors in high voltage environments

I am currently getting some custom cables made and having a serious communication issue with several cable manufacturers. I want several low voltage (5V DC) insulated conductors in a jacket that can ...
Jason K.'s user avatar
  • 319
1 vote
2 answers
411 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:...
Berchell's user avatar
1 vote
2 answers
174 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 ...
mthurley's user avatar
1 vote
0 answers
162 views

Do power strips need to have a breaker?

In North America we commonly use power strips to connect equipment to the building. https://en.wikipedia.org/wiki/Power_strip I noticed that some power strips have a circuit breaker, and some do not. ...
BetterSense's user avatar
1 vote
0 answers
414 views

What are the differences between UL1581 and UL2556 for VW-1 (Vertical Flame Test)?

In IEC62368-1, it's stated: Wire complying with UL 2556 VW-1 is considered to comply with these requirements. I've asked a manufacturer if he could meet these requirements and he answered that he ...
Carton_'s user avatar
  • 145
1 vote
0 answers
137 views

IEC grounding and bonding standard

Is there an equivalent standard in IEC such as UL 467 or IEEE 837 which talks about the various test procedure for bonding clamps? Is IEC 61914:2015 similar to UL 467?
Electronic Curious's user avatar