Alwayslearningelec
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WHAT DOES THAT ENTAIL???? Copper bus of course
If the bus is de-energized it doesn't involve much given you have the correct tools. Energized is a different story.
How the heck could you ever do it live??? Thanks
WHAT DOES THAT ENTAIL???? Copper bus of course
VERY, VERY carefully!! NOT recommended for long term life expectancy. Would do it differently today than I did it back then 12 or more years ago. I see infinity beat me to the reply so I won't bore you with the details. Same basic idea only I used a cordless drill.
Lots of stuff done hot
View attachment 6263
Sometimes with good reason, and sometimes not.
I'd have to have a really good reason to drill and tap a hot buss, I'm too old to do it just to prove I can.
Most likely you are looking at a bad spec. I did it once, copper is very soft, malleable, and the busbars get pretty thick so i was able to get a good hold cutting, tapping, for coarse thread bolts, but I did not like it. I would only do through bolts with high quality hardware after that. Did drill, bolt, and electrically tap a live main busbar once with a cordless drill. Never again.
"Tap" may mean drill and bolt a lug on the busbar for an electrical tap.
It annoys me when I see guys bolting lugs on busbars with the same hardware they hang pipe with, mild steel coarse thead bolts. Hardware should be minimum high carbon steel with fine thread bolts, grade five or better, with very good corrosion protection plating. Busbar bolting specs usually include Belleville concave washers. If you see silicon bronze bolts in the spec, that's marine grade corrosion protection.
Back in the day before cordless and double insulated drills
I did this 20+ years ago when I was stupid. I wouldn't do it today even with a cordless drill.
FWIW ...
Ordinary general purpose drill bits won't drill copper well at all. That have what is known as a 118 degree point. Look at the bit from the end, and you can see the letter "S" formed by the contours.
What you need to use is a 135 degree "split point" bit. This bit has a flatter point, and when you look at it from the end you see a 'bow tie.'
Drill with a slower speed and greater pressure.