Power supply grounding

[Martin Czech]

:::The second rule is that the signal ground inside should be kept
:::separate, but at some point connected to chassis ground with a
:::low-value resistor (under 100 ohms).

I wonder what will happen if someone touches the singal ground (jack)
and there is a short fault, some high voltage to signal ground.
I guess a current divider between 100 Ohms and the body.
All guitar stuff schemos I've seen (only a few) show signal
ground tied to protective earth and chassis in one point, with 
no intended resistance....

Or am I completetly wrong ?

m.c.