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Electrical safety for boosted voltage

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I've designed a LED driver that can drive LED strings of up to 75V but it suddenly occurred to me that this might not be a safe voltage. I know about grounding for mains powered circuits but this is powered from 12V or 24V. How should one deal with electrical safety in such a case? It is going to be used in a box that people are going to stand on with lighting coming from below shining through metal grating.

Depending on where you live, there are probably definitions for the parameters of what's considered a safe low voltage circuit in your electrical code.

In the US it will be called Low Voltage while in IEC countries it will be Extra Low Voltage.



Either way, 75V AC or DC will be out of the allowed range and you will need to either treat your system as mains voltage or reduce the available voltage to qualify.

The point of using a high voltage like this is to be able to drive two RGB LEDs (Vf ~ 30V) from three drivers instead of six so I would very much like to keep doing that. All of this is driven from one single 24V source which is a generic external power supply.

When you say I should treat the system as mains voltage, what does that mean more specifically? My knowledge of electrical safety tells me that mains powered devices need either very thorough isolation or safety grounding of all exposed metal parts. In my case, there isn't any dedicated safety ground since the system is only indirectly powered from the mains but I could go ahead and ground the metal grating the system ground so as to provide a low resistance path to ground if any higher voltage conductor should come into contact with it.

This kind of engineering is a little out of my league, especially not knowing what your project is. It may be that you'll be fine just bonding any exposed metal parts to the system earth or it may be that you need to add fusing to your secondary circuits as well. There are a lot of variables that come into play like whether the light source is separate from the box that it will be installed into, what kind of transformer you're using, will energized parts be accessible by some curious kid etc.

The plan was to have the boards mounted in a stack on a platform a decimeter under the grating along with the LEDs. So in use, you won't be able to reach the electronics.


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