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I have only worked with 220v single phase. Currently looking at a few places that offers 480v 3 phase.

Can anyone shed some experience on how i can  fully utilize the power.

1. How much work needs to be done, I plan to run 4x s9 per 208v pdu. So will need 10x nema outlets to begin with

2. Estimated cost ?

Most of the locations that i have seen are still being used by the previous tenant, and I see a lot of heavy machinery inside. Hopefully the places are fully set up for heavy loads.

I would suggest rewiring  to 220 single phase. What country are you in? You can’t run these on 480 3 phase.

You will need a transformer to step down from 480 to 208. From there you simply run 3 phase PDUs and balance the load accordingly.

You can't run 4 s9 per 208 30a pdu, they are rated for 5kW.  Even my 240v 30a pdus trip with anything over 3. 

Most PDUs split the incoming 30A in to two 15A or so circuit breakers. So you need to figure no more than two per circuit breaker of the PDU. Although 4 total is probably too close (counting inrush and possible high heat) as they run 6-7A per miner. Currently I have an S7 and an S9 on one PDU breaker and an S9 on the other. No plans to run more, once my M3s get here I wont run more than one of those on each circuit of my 30A PDU.

Like I said, you can't run 4.  I couldn't and I have 240v 30a units. 

I am getting about 6.1A max per machine ( includes +10%) - so about a 24.4a load on a 30A breaker , 30A wiring and 30A PDU

Cutting it really close, I ran it for 72 hours and the breaker and pdu wire is warm to touch, but not very hot. Breakers did not trip at all.

24.4 is fine for a 30A breaker - the 80% utilization is always a good rule of thumb.  When wiring, I typically have them jump down a gauge set when wiring things up, just to manage that warm wiring you're experiencing.

To your original question about 3 phase - as one person pointed out, you're probably going to need to step down to 208v or 240v, so you'll be buying a transformer for that.  The only other option is if all of your equipment can run at 277v, then you could run direct off of your 480v feeds - many server PDU's will handle 277v as will most server PSU's - but probably not your Corsair ATX PSU.  ;)

Are u sure it is a good idea to use step down transformer when u are running something 24/7?
Better to rewire to 240v? Wat if the transformer fails for a second? 400 volts would damage the antminer right or does step down transformers have some safety feature to prevent this?

Do you know how a transformer works?  Never mind, I already know the answer to that.

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OP,

As previous posters have said you will need to buy transformers to step your voltage down to 208.  The efficiency of these transformers and their placement will determine a large part of your system efficiency.  Place the transformers to minimize the lower voltage cable runs.  This will also save you wiring costs.

I read here that https://www.electronicspoint.com/threads/step-down-transformer-suddenly-stopped-working-but-why.263968/ and here says   https://www.techwalla.com/articles/what-happens-when-a-transformer-blows   it can get smoky/catch fire or explode if it fails but it wont damage the device....still too much of a risk imo

What Entropy-uc is saying is that the fact you're even asking that says you need to do a lot more research about how power gets around.  Utilities run power at much much higher frequencies than what you use at your house or at a commercial facility - and literally 99.999% of the power that's used is being converted through one kind of transformer or another.  You're not going to be running any miner that isn't behind a transformer of some sort - and probably two - one from the local power provider, and one that either you or the facility owner purchased.  Can commercial transformers explode?  Sure, but that's also why you hire qualified people to install them, and routinely service them, etc - to make sure nothing goes wrong.  Of all the problems I've run into with building and running commercial-scale mining, having a transformer blow up has never been one of them.

Plus the links you provide are way off - one is about utility grade transformers (super big), and the other is about electronics or system level transformers (super small), neither of which are applicable to what we've been talking about.  It's kind of like saying "I wouldn't use a transformer because sometimes they turn into robots and start attacking people."  While technically true in some situations, not really the same kind of transformers we're talking about there.  ;)

What does pdu mean?

Power distribution unit

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(Moderator's note: This post was edited by frodocooper to fix broken quote formatting.)

http://lmgtfy.com/?q=PDU (http://lmgtfy.com/?q=PDU)