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I'm trying to work through the parts required for an LED strip light project. I'm considering this power supply as the driver, driving about 20' of 24V LED strip. I've worked with similar but smaller power supplies in the past that were NOT explicitly labelled with Line / Neutral on the AC input side, but this one is in fact specifically marked with Line and Neutral inputs...

PWM-120-24 MEAN WELL

So my possibly stupid question is: is it safe/legal/permitted to wire this to a NEMA 1-15 non-polarized 2-prong cordset? A non-polarized plug would obviously permit the user to invert (intentionally or not) the polarity of the AC input.

I've also seen and worked with smaller power supplies that use IEC C8 connectors or extensions, which are non-polarized:

enter image description here

I can't seem to find anything explicit in the data sheet for the power supply, but it's also entirely possible that I just don't know what I'm looking for. I'd easily believe that ALL devices marked with L/N specific inputs must be polarized, or I'd also believe that there's something about these that tells you implicitly that they are safe to invert.

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A similar question has already been asked on SE Electronics, and Kellenjb's answer alludes to the fact that unless there was something extremely strange (like a practical joke level strange) happening in your voltage rectifier, there will be no difference between the positive and negative part of the AC circuit.

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This isn't an NEC question, this is a UL question.

Meanwell is a fine power supply (at least as good as you get with Chinese manufacture not from a Tier 1 supplier like GE or Philips) and it does have a UL listing.

However this listing is as a component not as equipment, which is why it has a RU mark instead of a UL mark. It is for manufacturers to build into their equipment, and the equipment's UL listing will go faster because the RU components are pre-approved and don't need exhaustive testing.

So to answer your question, you need to look at the UL design guidelines for equipment. You should follow those even if your production is too small to warrant pursuit of a UL listing. I'm not familiar with the gory details of that stuff, so I leave it to others who may be more expert.

  • The distinction between a component and equipment was important and not something I'd considered. Very helpful... – ljwobker Apr 8 at 19:48

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