Electronic – What would happen if water splashed on a 12v power supply when under load?

power supplywater

If I am running a 40A 12v power supply at approximately 32A, and a large quantity of water splashes onto it, what physical effects will occur in a worst case scenario. I'm sure I can expect short circuits within the PSU and for my fuse to blow. Will any sparking occur? If so, could they make it out of the PSU case? And could they persist for long periods or would the power stop flowing upon the first spark?

For the purposes of this question assume hard water with electrically conductive contaminants. Assume further that the PSU is hooked up to a power switch with a 45A fuse hooked up to a 110v / 15A outlet.

For clarification: This did not actually occur. I've just been playing around with a PSU doing some experiments and the question occurred to me when my daughter walked into the room with a cup of water.

Best Answer

There is a reasonably good possibility the supply will be damaged, so you should just assume it will be. Whatever is connected to the output might also get damaged due to over-voltage. You can not count on a excessive input current condition such that a fuse would blow.

However, the worst issue is loss of isolation between the AC input and the DC output. You have to basically assume that any part of the DC side is essentially connected to the hot side of the AC line. That can kill or injure any person that happens to touch the supposedly safe DC and ground at the same time.

If you really think this scenario is a possibility, make sure to use a ground fault interrupting breaker on the AC not near where the water can splash.

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