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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3 answers
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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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21 votes
4 answers
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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
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
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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
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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