I am totally unable to wrap my head around how electricity works, so I'm lost on this one. I have an older (90 years) home with a detached garage. I noticed a very slight feeling of current a couple of times when I flicked the light switch inside the garage. At first I thought I was imagining it. Finally, I figured something wasn't right so I called up one of my old Marine buddies who is a GC and told him to come over for a couple of beers cuz we hadn't hung out in awhile. Coincidentally, I happened to mention this problem while we were rehashing old times and he volunteered to take a look at it. He said, to paraphrase an old Marine saying, "This wiring looks like it was done by two monkeys 'doing something' to a football". He came over the next week and rewired the whole garage for me. Ok, the problem is this: Since then, I happened to be using a heat gun next to a 3" exposed exterior aluminum conduit. I briefly touched the metal tip to the conduit and got a pretty significant arc and a loud pop. Then, last week, I was cutting a timber with a circular saw using an aluminum speed square as a guide. (something I've done hundreds of times) As soon as I touched the saw to the square, my saw tried to electrocute me. Both of these tools were plugged into the garage outlet at the time, connected by 2-3 three prong extension cords. My questions are, "Are these two things related?" and "Would some issue with the electric in the garage cause this, or is it more likely to be with the saw and heat gun, or maybe the extension cords?" The saw is a good one, so I'd have it repaired, but I don't want to spend the money if that's not the problem. Any advice would be appreciated.

I replaced 6 worn outlets in my garage with GFCI to the tune of 75 bucks. Then someone told me that since GFCI's werent in the code when the house was built that I could have just replaced with standard duplex's. They found it funny that I spent all that money on outlets that wont hardly ever be used. What do you think?