Safety of electronic equipment?

Hi, I got a question about the safety certifications of electronics
equipment.

It happens that I was at my friend's office when some guy was peddling
his computer/electronic equipment to him. One thing that caught my
attention was when my friend mentioned that they are using X brand and
see no reason to change, this sales fellow claims that X brand is UL
certified at level 6(I think, wasn't next to them) while theirs is
certified at level 3 (I think). Thus X brand is more dangerous to
install/use compared to their brand.

I think it's just sales puff but I don't know much about this safety
thingy (locally, they don't seem to care). Though my common sense says
if UL has passed the equipment for safety, then shouldn't it not
matter whether it's what level?

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Frontpage bloats way more than dreamweaver.

 

Erm? Sorry, I'm not sure how to decode this in reference to my
question...

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Then you really are lost ;-) I never miss an opportunity to slam
FP.

I'd have tried google. You would've had an answer by now instead of
having to read my OT response. Find out what the different levels
of rating are. You'll probably find there's some difference in
flamability rating and insulation resistance or something. So maybe
the higher rating is for use in a different environment and it's
overkill for home/office use. As you said, "sales fluff". I call it
bs. But since we don't know what type of appliance you're talking
about or where it will be used, ain't gonna be much of an answer
forthcoming.

hmm... I just had a look at this Taiwanese computer PS I'm using to
power a circuit. It doesn't even have a UL sticker, just SA and
that backward RU thingy. The old computer it came out of never
fried and it hasn't fried since I cannabalized it, so I guess it's
safe if I don't spill anything on it.

Mike

 

Um, that backward UR thingy _is_ the UL sticker. They
changed it some years ago. (or it's a different kind
of cert, or something. I'd have to look it up.)

Cheers!
Rich

 

I thought that might be the case, but you say "some" years ago. I
bought the system... well... it was out of a 386 box. It was bought
used 9 yrs ago. I just dusted off the fan grill

I'll probably come across that info if I ever need to look into it.

Mike

 

It's their logo for *component* approval. The PSU isn't a finished
product.

Best regards,
Spehro Pefhany

 

Oh, so the reversed UL means the PSU is a component and safe as one
but not as a retail/finished product? If there's a forward UL label,
then it means a finished product suitable for retail?

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Hi, angel. Yes, that's right. Often with "C" and/or "US: meaning that
it's been tested by UL to meet Canadian and/or US standards. Note that
AC adapters (wall warts) are considered finished products. You'll also
see the backwards UR on disk drives, safety-rated capacitors etc.

Best regards,
Spehro Pefhany

 

Heehee, me bad, I messed up my siggy, so it didn't show up in that
post you were replying to.

I've been looking, the places that has the UL standards documents
demand a few hundred bucks before they'll let me at them.

Searching specifically for UL level 6/six usually brings me to product
specifications and the level 6 usually refers to CSA instead of UL.

Since you mention a Taiwanese PSU, let's use that as an example. After
all, I would like to learn how to figure this stuff out on a generic
basis rather than knowing only how to read the info for say a
soldering iron PPp

I looked up UL for two famous brands, Enermax and Antec.
http://database.ul.com/cgi-bin/XYV/...n=versionless&parent_id=1073992443&sequence=1
http://database.ul.com/cgi-bin/XYV/...n=versionless&parent_id=1073992443&sequence=1

Neither of them tells me what level those things are certified to. In
comparison, google searches usually refer power supplies to UL-1950...
there's no such code on those pages, the closest thing to a category
code I can figure, is "QQGQ8"

Another thing is, I seemed to have dug up a can of worms when looking
at the info for this example. Some of the models are lumped together,
like the True480 and True550 for the Antec, with one single set of
ratings. The 480 and 550 model have different ratings according to
Antec. Does this mean that the 480 is actually capable of outputing
the same level as the 550?

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This is weird, I've seldom seen the forward UL symbol in most retail
packed stuff here. Does that mean these things are actually NOT safe
for consumers to use? Is that why some of them have wording about
Professional Installation required?

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They could be using another testing lab with a different logo and
perhaps testing to different standards. I'm not sure what offical
testing is required in your steamy little city-state.

Maybe this is what they have?
http://www.spring.gov.sg/portal/images/safetymark.jpg

Probably some kind of CYA (not CSA) thing.

Best regards,
Spehro Pefhany

 

I read in sci.electronics.design that The little lost angel <[email protected]
overgirl.lrigrevol.moc.com> wrote (in <
et.sg>) about 'Safety of electronic equipment?', on Fri, 12 Dec 2003:

You are asking in the wrong newsgroup, although I think it's very
disquieting that none of these designers know anything much about safety
standards.

The appropriate news group is sci.engineering.electronics.compliance,
but even better is the IEEE emc-pstc mailgroup.

Unless perhaps you are dealing with equipment for hazardous atmospheres,
there are no 'levels' in any electrical product safety standards that I
have ever seen. I think the salesman was emitting pure BS.

 

For CSA and the US equivalent (NEC Article 500, in this case),
hazardous atmospheres are grouped: "Class XX", "Division NN" and
"Group YY", where XX is a number in Roman numerals, NN is a number,
and YY is a letter. No "Levels" involved, and no numbers greater than
2 or III.

Actually, it looks to me like he's talking about computer networking
cable standards which are of tertiary interest to most of us.

Best regards,
Spehro Pefhany

 

---
Some of us do.

I've done a couple of designs which were beat up by UL and passed, but
I don't usually like to offer "advice" re. safety standards other than
referring an enquirer to specific documentation if I can remember it.
---

 

Spehro didn't get that joke and maybe it was unintentional, but I
understand what you didn't say. That was good. 2 approved
components in an approved cabinet and it isn't approved.

I wonder how that could affect some companies out there. I build my
own boxes from components but I do have an old HP Vectra XU and
it's got a UL logo on it. I've never bought a box cobbled together
per my specss from a company.

Mike

 

When I apparently don't get a joke it is *always* intentional. ;-)

FCC is probably at least as big an issue.

Best regards,
Spehro Pefhany

 

No, my fault. I top posted and the hyphen in your sig causes news
(& mail, IIRC) clents to not quote that part since the "who said
what" is posted at the top.

Before I go furthur, would someone please post the link to that
site that converts long links to short ones for this girl? Those
links below are a PITA and I can't find where I stashed the link
right now.

I'm not surprised. The current ansi/iso C++ standard is $750, but
the working draft is online.

Forget my PS example. I couldn't discern a specific question
regarding that, anyway. Try what John said.

As for designers not knowing much about safety standards... pay no
attention to the man behind the curtain. I look up stuff that isn't
burned in bio ROM so I don't fry anyone. I use stuff that's been
known to work, and personally, I haven't had to deal with looking
up the UL crap so far and rue the day when I do. It was bad enough
sorting out the FCC crap so I'll probably consult with a cert lab
for any future UL woes.

<snip>


BRs
Mike

 

I would think someone was exposed to it at least indirectly. It
would have to be someone who designed connectors or boxes or was
responsible for UL stuff in one way or another. Maybe someone
responsible for writing the specs that get passed to the designer.
Your statement is too broad. You said yourself that you've never
heard of specific levels, so the whole question was hosed. Sales
bs.

See if you can find UL stuff in a NEC handbook or the EE bible. My
relay's rated for 10A, it'll work. My traces will handle the
current, blah, blah... My box manufacturer uses ABS plastic with UL
flammability rating X. WTF do I care about the details of how he
did the flammability test? Use a UL approved IEC connector with or
without EMI filter and don't worry unless you need to get the
assembly approved for sale to the public.

Chances are, the people that look that crap up aren't good enough
to be designers. Just like the idiots at the patent office that
issue patents that can't be enforced or on crap products. If they
were good enough to be designers, they wouldn't be pushing papers.

Mike

 

Don't I know it. I just never delved into UL and figure it's as
convoluted a read as title 47, but I could be wrong. I hope I'm
wrong.

Mike