Really, leaving only BM? Why do so many forget about Canaan?
Excellent reputation all around. Availability either direct or via distributors - check. Deliveries - on time. Build quality - stellar. Prices - decent.

Another overlooked point of energy use is video streaming. ref https://www.bbc.com/news/technology-45798523
From the article:All in all it makes the energy used by crypto mining rather insignificant.

Happy birthday!

The key point to remember with s9's is that the fans have to work against a fairly high airflow resistance cause by BM's insane mass of small heat sinks. That means they have to produce high static-pressure which is why they run high rpm. That in turn = loud.

Unless the miner is UC/UV'd there is no getting around this.

Oh I agree 100%. Not normal practice and I'd certainly need a good reason to do it (and really cannot think of one) but - NEC does not forbid it.

Ja. The regs were not written just for the heck of it.

Back to the bit about running a 220v line to a NEMA 5 duplex outlet: Some clarification is needed.
Thanks to the North American split-phase power setup technically it can be done BUT and again with a huge BUT, it is done as 220v with neutral to deliver 120v to each receptacle.

If you look at most NEMA duplex outlets you will see each pole has 2 screws for wire and a brass link joining the contact pads together. For one, it makes it easy to daisy-chain circuits -- but -- when the link on the hot side is removed it also allows L1-N (110v) for one socket and L2-N (also 110v) to the other socket, in fact on many/most NEMA duplex outlets the link is scored to be easily broken off. The single neutral wire feeds both sockets via the link on its side. Considering that the device (duplex outlet) is only rated for a total of 15A due to thermal considerations, not sure why one would want to do that but it is allowed as the end result is 110v at each outlet.

Perhaps that is where the electrician went wrong by misunderstanding that one exception?

If you are in North America, from what you are saying that there are so many code violations it is not even funny and that electrician needs a hard smack in the head as well as go back for a refresher to his training.....

a) an outlet type MUST match to voltage/current feeding it. In your case the outlet/plug MUST be NEMA 6 that is used for 208-250v service. Yes a NEMA 5 (110v) outlet will not explode if fed with 220V but there is nothing to prevent someone from plugging a 110v device into that 220v outlet with disastrous consequences. Even worse, if there is a fire anyway related to the wiring an insurance company will happily refuse a claim due to such egregious code violations.

b)wiring and breaker to an outlet MUST be sized to the outlet: you CANNOT power multiple 15A single or duplex outlets from a 30A breaker for the simple reason that if overloaded that 15A outlet will burn as will any cords not rated to carry 30A.

c) as Phil said, the 15A rating applies to the entire outlet. Be it 1 cord or 2 plugged in the maximum is 15A total.

When it comes to electrical power wiring there is no 'well, as long as you <conditions>, you can get away with <bad practice>'. You either do it/have it done right or not done at all. PERIOD.

Damn, still running one of them? Talk about a power hungry beast! Definitely the best looking miner BM ever made  
I still have one of mine from ever so long ago now sitting in storage and donated 2 others to Sidehack that he used to use as heaters.

As to the 7 blocks in 4 days -- has to be a bug in the old cgminer software as it is simply not possible. Perhaps it is tied to the diff being astronomically higher these days vs when the s4 was made?

Not to mention that their factory Support is near non-existent but that and what Pass said has been well documented here ever since the Ebit series of miners were introduced a few years ago.

I wish you luck with them but highly suggest that in the future you avoid the Ebang products like they are Plague.

Screw that ^^ noise. There is nothing about these small miners that needs the things that Stratum V2 and BoS is supposed to provide, it largely increases communication between servers and miners with the aim of 'better management'. For that matter for most folks, it has nothing any miner 'needs'. Beyond that, V2 is mostly a case of change-because-we-can: a disaster in the making that should be discussed elsewhere.

Ja cgminer relies on using usually closed-source drivers specific to any given miner - so what? It works very well and more to the point, has a proven track record that it finds blocks - something the devs behind BoS and the various hacked firmwares out there have yet to give ANY proof of.

With the latest SW/FW from Canaan they made the A841 easy-peasy to turn into a heater. As I said before, just use the Low Power mode and in the additional commands use:
  --Avalon8-fan 10-30

You now have an instant quiet heater pulling around 750W and giving around 8.5THs. When it 1st starts up for the next 3 minutes the fans run at 100% while the miner does some tests. After the 3 minutes have elapsed -- near silence In a room around 72F and lower the fan coasts along at only 15-20% speed and is extremely quiet, in a room 75F and higher it will run up to 30% fan speed and yet still be very quiet. At 30%miner fan speed the fan in the APW3++ PSU I use is louder.

The only drawback to them is the need to use a RasPi controller in each location you have them though of course you can run multiple miners in each location off the 1 controller.

Both GE and Siemens make them as well. No doubt because in the US, boxes using stab connections to the bus bars are very common though not sure if still allowed for new construction. I recently had to replace my main 100A breaker at home due to one of the sliding stab contacts on the breaker getting weak, then getting hot and finally giving up the ghost. Had no trouble finding a replacement at Home Depot.

Point is, the software is primarily for altcoins and belongs in the altcoin area where you will find many folks who mine alts and who might try it- not here (edit: was originally in Bitcoin Software area). Expect the mods to move it again.

Really do not think someone should try running software from a company that does not even know the difference between altcoin hardware and Bitcoin hardware or the software used in said hardware. If they are gleefully willing to ignore the rules about where to post (altcoin mining software) what else are they more than happy to ignore?

I prefer using Canaan's Avalon 841 for quiet heaters. I have a few spread around our facility and a couple at home.
In low-power mode and fans set 30% max can be used in TV room and even bedroom if ya don't mind a little white noise from whatever PSU you use. Will run at 8.5 THs or better.

No, you can replace the driver that cgminer uses and use the OEM one but that would most likely break the modified cgminer code. cgminer is a generic mining program that relies on a driver to communicate with a miner. Each kind of miner has a custom driver that is written for it and that driver is (well, was) the 'secret sauce' that the manufacturers do not want released.

One has to assume that you are using non-OEM firmware for various reasons such as tweaking speeds & chip voltages. However if you change cgminer - or the driver - you lose those supposed advantages to the firmware making it a rather pointless excercise.

Sort of. It is coded into the driver that cgminer uses to interface with a miner. More specifically it uses the #xnonce function to parallel mine to a different account (the dev ones). That in itself is one of the issues (using #xnonce) [edit: or is it #xnsub?] some folks have with the software as it opens a security hole to do work - ANY work, not just mining - that is invisible to the operator of the miner.

First I've heard of that one. Sure you got that right?
I do know that some exchanges will not accept freshly mined coins. Why? Because there is no history (coin inputs) behind them but that is more of a lazy accounting software issue. Those exchanges that care (Coinbase for one) will usually ask about the source of coins when you register with them and once you tick that box they are happy.

As for some coins POSSIBLY being previously used for illegal activities - a total non-issue and only on the radar because of uninformed press writing about it and spreading FUD.

No.
Unless a miner has their payouts pointed to your wallet, coins will first show up in the miners wallet. After a miner sends to you that would make you the 2nd in the chain of coin  'owners'.

Frankly, unless you are doing something illegal to begin with why on earth would you care about a coins previous history? Even then unless there is some connection between your (illegal) activities and previous coin owners, a coins history is meaningless. Paranoid much?

It's rather like saying you only want freshly printed paper money because used money often has traces of cocaine on it.

The OP mentions a BeagleBoard -- if their S9 has one (as a daughter board plugged onto the main control board) then yes it is from the first few batches. The BB was used up to batch-5 and it was with batch-6 that they started using the 1-piece XILINX control board.

If they do have one of those old batch-1 thru 5 miners they also need to be aware that the hash boards are different: They have no Vcore regulators and instead are directly fed from the PSU. Given that, there is NO way to change the Vcore voltage as can be done on later versions that have the on-board regulators.