I am going to have electrician run 3 #8 20 amp dedicated circuits. 1 for each monoblock and one for a power conditioner all terminated with furtech or similar receptacles. What type/ specifications for grounding should I require 




I would think the electrician will be following the electrical code. If you need something extra, you probably will have to get a grounding apparatus like those offered by companies such as Synergistic Research and Entreq. 

You might think about 30 amp service if you want to run some of the mega watt amps. 

#8 won’t fit any receptacle. There is NO need for anything beyond #12 on a dedicated 20 amp. If the run is so long there is a voltage drop, you should have ran a 220/240 sub panel anyway. Save your money and BUY good copper Romex along with Hubbell receptacles.

Use L1 or L2 but don’t use both for the dedicated circuits. I don’t know what your wattage use is but #10 will run a huge AC unit.. Are you trying to make sound for a football stadium?

I use SOOW 4/3/g for an extension cable in the back yard, that runs anything including my stick or wire-feed welders. The wire-feed recommends #10. What are you running? :-) With that SPL potential you could use it as a personal home defense system. Brain scrambling able.. Kill every bug within a 5 mile radius. LOL