... the only thing you need to do when planning on buying Bitmain 17 series is to reconsider your decision because chances are you are going to regret it...
lol, mikeywith just loves those 17 series. I think there are situations where it could be ok to buy some 2nd had 17 series, but at current prices, it doesn't make sense. Prices for used gear aren't much lower than new gear when you compare $/TH, so just buy the new stuff that comes with a warranty.
And with new 100TH miners running >3Kw instead of 2Kw, you'll need fewer circuits so it'll be a bit cheaper to get your wiring installed. But either way, you should make sure the wiring can support the newer gen miners. Probably doesn't cost much more to put in wire that can handle 30A rather than 20A.