Which wire is hot and which wire is neutral?

You can buy a pen style inductance tester, which will pick up the magnetic inductance generated by the hot wire if the circuit is on. They are not 100% reliable, but if it lights up on 1 wire and not the other, and flipping the circuit breaker on and off makes it come and go as expected, that would be a very good bet.

The problem with the wiggy tester suggestion is you need something to test the wire to, since a wiggy requires 2 connections to test between all you could do with it is test the voltage between the 2 wires, which does not indicate which is which. In a grounded system this would work fine since you would find voltage between the hot and the ground, and not between the neutral and ground (since the neutral is grounded).

Actually, if you run an extension cord from a different circuit in the house (single phase systems like yours have 2 hot legs, the cord would have to plug into an outlet on the OTHER hot leg) you could use a wiggy type voltage tester, you should get 220 volts from the hot on the extension cord to the hot in your wiring box, so that would show you which one is the hot. Take care to not fry yourself! Maybe you should call an electrician!

If you mean "National Electrical Code", in the USA, then you're wrong that converting 2-prong to 3-prong is "against code", provided you install a GFCI in the first outlet on the branch. Your electrician will know exactly how to do this for you safely and according to modern code.

Unfortunately, old wiring can be extremely dangerous, due to conflicting codes over the years and you have no idea who installed what you have, or when, and whether they were any more qualified than you are.

Yes, "black" is normally the "hot" wire (or brown in most other countries), but the only sure way is to use a testing instrument to determine which one is energized.

Add: As a local lineman told me, "When working with dangerous voltages, it only takes a half a second to become dead forever."

Typically here in the US, in a standard residential setting, then Black is going to be your hot wire, and white your neutral. You can't always assume that though because black or white can also be used as a traveler in a 3-way switch. However I doubt that is the issue in your case. For $10 - $15 you can get a voltage detector (tick chaser) that when the button is pressed and it's near a "hot" wire, it will emit a beeping sound. Those work but can also lie to you and cause you to get shocked. I would recommend getting yourself a volt meter (with the two leads) if you plan on doing anything with electricity. They are much more accurate and an essential tool for electricians.

Some advice: If you have cloth-covered wiring in your house, then you need to get those parts re-wired as soon as you can. That stuff can't be grounded and it just unsafe in general. As that cloth coating gets older it gets crumbly, and will fall away from the wire.

To me it sounds like your out of your depths fiddling around with something you know very little about. Electricity is a killer!

My best advice I can suggest to you is call a trained electrician, as he will have all the equipment for testing wiring.

As one other answer suggests that you purchase a tester, but locating an electrician that will work for cash is a much safer option in my book.

Cheers!!

The black is hot -- even if it has white writing on it. The white or yellowish white will be neutral.

You can purchase a very inexpensive tool (about $5.00 at Home Depot) for always determining if a wire is hot. It is a small neon light in a plastic housing with a pair of pigtails protruding. If you touch one lead to any wire and hold the other pigtail with your fingers, the light glows to indicate the presence of current, or not if there is no current. If you touch the pigtails to a pair of wires, one of which is hot, half the light glows, indicating the hot side.

never assume a wire color is carrying the correct current. pick up a voltage tester and test each wire to see if it is hot or neutral. a wiggy type tester can be had for under 40 dollars, or an inexpensive dvom meter in the same price range.

I am not even going to ask what country this is.

I know from experience, that the far east don't follow any colour code

but in the UK

we stick to Red and Black

or Brown and Blue

red and brown being live

and

Blue and Black being neutrel

ok, here's what you do. Fill up a bathtub with water, and sit in it. Then, submerge one wire at a time in the bathwater. The wire which causes you to lose consciousness is the hot wire.