In Canada, engineers are issued an iron ring after they take Rudyard Kipling's engineering oath. It is to be worn on the little finger of the dominant hand. Mine is actually made of stainless steel:

These rings are not to symbolize membership in some secret society, they are a simple personal reminder of the responsibilities of being an engineer.

Being steel, they are very strong and can be used as a tool in all sorts of applications (bottle opener, electrical jumper etc.)

I had a friend who wore his iron ring while working on a vehicle. He was removing the positive lead from the battery when his ring touched the vehicle body. Current ran through the wrench and through his ring to the chassis. The ring, which is not a great conductor, instantly got red hot and badly burned his finger - it looked like it went right to the bone. He was very experienced with vehicle work and knew the rule that you always remove the negative lead first, just got careless. An accident like this can cause the wrench to weld to the ring and the ring to weld to the vehicle, which makes it hard to stop the heating process. I am not sure if this happened in his case.

Unfortunately or fortunately I don't have a picture as the wound was horrible to look at. (It eventually healed remarkably well).

I did snag a couple of internet pictures of what a ring (not an iron ring) can do to a hot dog when shorting a much smaller battery:

Most people are very careful around high voltage apparatus, but if you wear a ring, you need to be careful around low voltage as well.

And always take the negative lead of a car battery off first. When jump starting a car put the negative on last and take it off first.

It may be cool to use a ring as a tool, but it is easy to forget that it can be dangerous. A steel ring is strong enough to take a finger off if it gets caught on something. (I don't really think rings are very dangerous in general, but that makes these unusual cases more poignant.)

I actually never wear my iron ring, I only put it on to take the picture above .... and I still have all my fingers.

dougw  As a female of the group, you must do three things:

1. remove your rings!
2. remove any dangles ie long neckless, scarfs, and or earnings.
3. Put up your long hair.

The list is in the order of pain!

1. Ring: Could lose a finger or worse! when playing with power!
2. Hair: Can fall in to or get caught by machinery.
3. Neckless: Can fall in to or get caught by machinery.

dougw  As a female of the group, you must do three things:

1. remove your rings!
2. remove any dangles ie long neckless, scarfs, and or earnings.
3. Put up your long hair.

The list is in the order of pain!

1. Ring: Could lose a finger or worse! when playing with power!
2. Hair: Can fall in to or get caught by machinery.
3. Neckless: Can fall in to or get caught by machinery.

Good points - back in the day when I wore a tie every day, I always removed it before going into the machine shop.