Electrolysis of water using 240V AC I remember back in my high school, when we started electrolysis, I became quite interested in it. I decided to do a home experiment on electrolysis of water. I grabbed my graphite pencils, a glass of water made of steel, two wires and some water. I wrapped the wire on my graphite nibs(on one end) and immersed the other end in water. I connected the wires to 240V AC supply(that was the supply which powers our home.) 

Observations:

Initially, bubbles formed on both of the electrodes(I think they must be a hydrogen/oxygen mixture since the cathode and anode switches in between due to ac)

The glass of water became very hot with the passage of time(which was due to resistance heating i suppose)

The interesting part came when I added a few grams of table salt to water. Within seconds, the graphite rods turned red and there were fumes of gas(most probably it was steam cause the fumes were white.) There might have been sparks in the plug as well, but I don't remember for sure. I immediately pulled the plug out before it got any worse.

I didnt try anything of that sort again as i knew i could have done worse than that. But it doesnt cause any harm in knowing what actually happened when I added salt.

Why did the graphite turned glowing red?

What was the composition of those fumes?

What more could have gone worse?
What you are trying to do is called a redox reaction (from REDuction-OXydation) in which one molecule will be oxidized (i.e. give one electron) and another will be reduced (i.e. receive one electron). The propensity of two different molecules to exchange electrons is called "redox potential" and measured in Volts.

In the case of water, its dissociation into hydrogen and oxygen has a potential of 1.23V(1), so a 1.5V battery would be enough (however a rechargeable battery usually has a potential of 1.2V which would not be enough).

In your case, you apply a 240V potential, which will not only promote many other reactions but also heat the water up because of the Joule effect and make it boil.

(1) I purposely ignored the sign not to confuse you.