It's not difficult to drill a hole in a cast iron pipe. This sort of metal is the most dense and hardest metal available for use in modern-day homes. This means that oftentimes drilling a hole through this sort of pipe can be a bit time-consuming. You can't drill through a cast iron pipe with one drill bit. You'll need to use an array of drill bits to get the desired size of hole that you want. The trick is to slowly increase the dimension of the hole.
Things You'll Need
Put on the goggles and gloves. Connect the electric drill to the drill bit. Drill a hole in the cast iron pipe. Grip the drill firmly while you use it.
Increase the size of the hole by changing your initial drill bit to the next size in your bit kit. Use the drill on the exact spot when you use the bigger drill bit.
Swap the current drill bit with an ever larger size. Slowly enlarge the size of the hole you are drilling. Do this by using increasingly larger drill bits that came with your drill. Replicate the entire procedure until you have made the hole in the size you need.