About 10 years ago we had plumbing problems in upstairs bathroom above the bedroom in garage. Plumber tried to unclog the sewer line via roof top. The next day or two there was a huge leak in ceiling of garage bedroom, the plumber had knocked lose sewer pipe joints. The ceiling and wall were soaked with sewer water.

After having sewer pipe repaired I decided to wash the wall with bleach water to kill germs and when I touched the sheet rock with metal handled mop I was shocked. Could not imagine why sheet rock would shock me.

In disbelief that sheet rock could possibly shock like that I tried again, same thing. Threw down the mop, called my husband...he did not believe me and was going to touch the wall. With my screaming at him at top of my lungs finally got him to not touch the wall and to go turn off house electricity.

Called an electrician from a commercial electric company and he could not believe sheet rock would shock me. He found out the wall was indeed "hot" and took a while to find out why the sheet rock was "hot". The electrician my brother brought to wire the bedroom had wrapped electric wire (220) around a stud and then nailed through the wire.

Very alarming to me to realize our teenage daughters had been using the bedroom for many years with a "220 hot nail" in the wall.

Reason for my posting this story is to warn others to be sure you have a "good electrician" regardless who hires them, watch what is being done and pray you never have similar experience.

I am still shaking in my boots thinking about what could have happened in all those years with a hot nail in the wall.

The electrician I hired from the commercial electric company told me in later years that he had "great mileage" telling my story to others. It was a story to top all stories!

The nail was only at 120 V to ground.

You need to across both 120 V legs of the circuit to get 240 V.

Nails and screws hit cables sometimes.

Often is enough of a short to trip the breaker.

Sometimes it does not.

I've had wires that were meant to be stubbed out of the wall pushed back in and pinched between the rock and the stud and screws driven through them. Sounds similar.
I've had them drive screws right into the back of boxes before too, because they missed the stud on the opposite side, who knows why they were using 3" grabbers.
Hell, one time the siding contractor did the same thing, only right into the bus of my panel that was on the other side of the wall.
Point being, it might not have been the electricians fault.

but who knows what really happened. I just find it hard to believe that a licensed electrician would do that, and it would pass a rough in inspection (again assuming you had the proper permits and everything, right?)