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Topic: Safety considerations (12V LED lamp with arduino) (Read 628 times) previous topic - next topic

dosox

Hello everyone,

I've built an arduino nano clone, a 12V power supply and a bit of digitally-adressable LED stripe into a small children's lamp (if you're curios, here's a more detailed description with pictures). While it works just as intended, I find it difficult to get a grip on possible safety considerations (might I have made a mistake somewhere - how likely is this thing to burst into flames?).

Currently my approach is very simple:
- only use it when we are in the same room (but not as a night-light for our child)
- have a fire alarm in the room (they're mandatory in Germany anyway)

However, are there safety guidelines or recommendations I can consider, and maybe steps to either test or improve the safety? I've already hat a look at the forum search and found this post as a starting point: http://forum.arduino.cc/index.php?topic=1980.0

Coding Badly


Does the power supply have a genuine CE mark?  UL mark?

Are any parts too hot to touch?

Is all conducting metal insulated?


raschemmel

I would add a flame senor and piezo alarm because by the time your smoke alarm goes off it's already too late.
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terryking228

Hi,
Tell us details of the power supply you are using..  And what certification marks it has..

The 12V DC is not itself a hazard..  40 to 48 VDC is the usual point at which a device is not considered intrinsically safe for human touching.
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
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raschemmel

Quote
40 to 48 VDC is the usual point at which a device is not considered intrinsically safe for human touching.
I was told the Fire Marshall uses 35V AC or DC as the maximum safe voltage without a special permit for equipment used in party rental equipment where the public comes in contact with the equipment and could conceivably touch some wire.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

dosox

Does the power supply have a genuine CE mark?  UL mark?
Are any parts too hot to touch?
Is all conducting metal insulated?
The power supply (12V CD with 5.5mm pin) has a CE mark with IP20 under it and also a TÜV (general testing autority in germany). It came with the LED stripe so I'd assume it is built for long-time use.
I can touch all parts during operation and have insulated conducting parts (well... somewhat, I might add a bit of insulation tape here and there).

My main concern would be a failure like this:
- something in the arduino breaks (maybe in my soldered circuits or the LED strips) and makes the arduino overheat (the power supply can provide at least 20W which should be enough for electronics to get VERY HOT).
- the surrounding wood or paint parts start to burn

But basically, this is a concern that should apply for almost all arduino projects with A) some soldered parts and B) powered by a 12V power supply. So I think I'm still looking for some kind of safety guideline manual for long-term parts in potentially flamable environments (like "arduino mounted on a wood plate", not like "arduino operating close to a H2-source").

septillion

Then just add a fuse. And triple check wiring.

The Arduino itself will not overheat, biggest concern would be a short circuit.
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Coding Badly

#7
May 26, 2016, 08:43 pm Last Edit: May 26, 2016, 08:59 pm by Coding Badly
The power supply (12V CD with 5.5mm pin) has a CE mark with IP20 under it and also a TÜV (general testing autority in germany).
Protection from fingers (IP20).  An odd thing to include on an enclosed power supply.  I guess if you can include it, why not include it.

As for TÜV, it is simply a question of trust.  For example, I trust UL (Underwriters Laboratories) for a fairly long list of reasons.  They have a way for an end-customer to verify that the UL mark is genuine.  If that mark is on an electrical device I trust that it will not start a fire if used correctly and that it will not result in an electrical shock.  If you trust TÜV and the mark is genuine then it is reasonable to trust the power supply.

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It came with the LED stripe so I'd assume it is built for long-time use.
That would be my assumption.

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- something in the arduino breaks
Don't let your child chew on it!   ;)

Quote
(maybe in my soldered circuits or the LED strips)
Mechanical manipulation (vibration) or heat could cause such a failure.  Don't let your child obsessively wiggle any wires!  ;)  (You've already confirmed there is not a heat problem.)

Quote
(the power supply can provide at least 20W which should be enough for electronics to get VERY HOT).
As @septillion said, add a fuse.

Or not.  If the power supply is good quality it will have short-circuit protection.


Do you have smoke / fire detectors in the sleeping areas?  Are the batteries fresh?  Are all conducting wires insulated?  Is the power supply reasonably good quality?  For me a "yes" to those questions is enough to allay any fears with a project like yours.  (I have a few similar that are left on all the time including one the dog can reach.)


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