Difference between revisions of "Common symbols around you"

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<br style="clear:both">[[File:CE and CE.png|thumb|69px|right|CE Mark and Chinese Export]] There are also a bunch of fake symbols.
<br style="clear:both">[[File:CE and CE.png|thumb|69px|right|CE Mark and the more suspect one]] There are also a bunch of fake symbols.
Best known among them is chinese producers just stamping on the european CE mark.  
Best known among them is chinese producers just stamping on the european CE mark.  

Revision as of 13:25, 26 June 2020

Uses, safety

Some mark mentioning RoHS means it's compliant to RoHS

Power supply

basic AC-to-DC adapter specs

The top symbol is for DC barrel plugs, specifying whether the inside or outside is positive.

The middle line is input, where the squiggly tilde ~ indicates AC, here mentioning an input voltage range and frequency it's okay with (these specs amount to worldwide use).

The third line (output)'s solid and dotted line indicates DC.

LPS (Limited Power Source) have relatively low maximum voltage, current, and power. [3]

SELV (Safety Extra Low Voltage), where the power supply output stays safe under single fault conditions. [4]

Transformer (general)

isolating, safety isolating;    non-short-circuit proof, short-circuit proof

separating transformer, output >1kV, variable, constant voltage, perturbation attenuating

Double circle, like a vertical venn diagram, are transformers, with a handful of properties marked. There are more combinations of all the parts this image shows, and further ones (e.g. construction site).



Some of the more commonly seen logos / certification bodies include:

Bunch on European certifications

There are actually many more testing centers, that may deal with additional health and/or safety and/or environmental concerns, and in many cases it's largerly just country-specific.

You're probably used to the logos for your part of the world.

Certification marks, in the end, represent agreements between manufacturers and (ideally well known) testing centers.

Note there are also logos that do not mean that.

In many places certification marks are not strictly required for sale(verify), yet certification is common for a collection of reasons, like you caring about your safety, liability in terms of insurance, and varied indirect regulation (e.g. electrical code, fire regulation, medical safety) meaning certain places/resellers only buy certified devices, or even just self-imposed regulation like you caring more that your house/business is less likely to burn down.

For some devices (e.g. separate power supplies) you can see more-than-usual certification marks, for practical reasons: e.g. when a large company that has locked down the design so that they can mass produce it, for worldwide sale, without a lot of new certification (certifcation is slow, sort of expensive, and may need periodic recertification).

CE Mark and the more suspect one
There are also a bunch of fake symbols.

Best known among them is chinese producers just stamping on the european CE mark.

Often with different, tighter spacing, presumably to to have an argument it's not the same (but this tighter spacing is also used in some CE products for spacing reasons).

This has been nicknamed "chinese export".


A bunch of markings used around mechanisms, indicators, and buttons, around cars, audio, production lines are settled in ISO 7000 / IEC 60417, see e.g. See https://www.iso.org/obp/ui#iso:pub:PUB400008:en

IP ratings for water and object safety

clothing / washing labels

Packaging symbols




Single use, keep dry, don't use if package damaged