Electrical – Can an RCD protect against transformer failure

electricallow-voltage

I want to install LED lights in a pool. The original transformer outputs 12V 6A. Now I don't trust my life to a cheap transformer so I want to go sure. Yet I also don't want to spend more money than necessary. I don't have to live for ever.

Found an adapter that measures residual currents and breaks the circuit if delta larger 30mA. RCD safety adaptor So this sounds quite good to me.

Now I wonder, isn't it possible that in a worst case situation this device would not measure any delta between both power lines and the human between both lines beeing effectively roasted?

Found out that cheap transformers can output the full incoming current in a state of failue. Safetytransformers where a short circuit is not possible by design cost quite some money.

Is such an RCD adaptor a safeguard for any transformer failure?

Edit: Would it help to ground the poolwater – lay a cable from inside the pool to the grounding connector in the power outlet.

Best Answer

Yes, it would, but 30ma won't belp you in a pool. Here's how electrocution drownings work.

  1. Current as low as 10ma stuns the person in pool.
  2. They faint.
  3. Where they fall, their nose or mouth are under water.
  4. They drown.
  5. Rescuer sees them unconscious, reaches out or jumps in to save them.
  6. Current stuns rescuer.
  7. Go to 2.

You think I jest, but often the way they know it's an electrocution drowning is multiple victims. The coroner can't tell an electrocution drowning from a normal one.

What you want is personnel-grade 8ma protection.

Another defense would be to tie your DC negative terminal to the local grounding electrode system. This means the DC is no longer an isolated system, and is a potential ground-fault path for your AC system.

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