A few questions for setting up multiple Antminers in my house: L3+ and D3

[techguy91]

My plan is to put each D3 on a separate 20amp circuit as they run 1200watts.

I was thinking of doubling up and putting 2 L3+ machines on one 20amp circuit since they run 800watts...  Upstairs in my house 2 rooms share a 20amp circuit - so 1 L3+ in each room.  

I was thinking about using extension cables to run all the Antminers downstairs so I don't have to run my 2nd AC unit upstairs (costs $150 to $200 a month 6 months out of the year just upstairs alone if I run it) or should I not do this?  I read the extension cords have to be fully extended, at least 15amp rated and only 1 machine per cord.

Will the Antminers need to be connected to a power surge strip or does the ++ Power supply Bitmain sells handle power surges?

Thanks

Summation

1. Should I put 2 L3+s on a 20 amp circuit, using separate outlets on the circuit?
2. Running 5 or 6 extension cables from upstairs to downstairs to run all my machines downstairs so I only have to run the downstairs AC half the year?  Too dangerous?
3. Do the Bitmain ++ Power Supplies need to be connected to a separate surge protector then into the wall?

[MATHReX]

1. It is perfectly fine if you run 2 L3+ on a 20 amp circuit if nothing else is connected to that circuit drawing power. Definitely run them on two different outlets.
2. Are you suggesting to connect 5/6 different Extension cords from upstairs to downstaris connecting them one by one? If yes, get just one extension cord with preferable length such as 10-15 meter or so with built in surge protector. Their won't be much difference in price.
3. No, I don't think its required. Bitmain ++ Power Supplies are actually platinum server PSUs which are very efficient and comes with all kinds of protection built in.