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I'm trying to determine how many miners I can run and how I will get electricity to them. The building I have is being upgraded to 100amp service (from 60) and I will be able to add circuits directly to the breaker (or have a qualified electrician do it for me).

My prototype machine is saying it's 5.35amps, 420W, 116V (Killowatt). *note that 116V * 5.35amp != 420W :\

How many machines can I run from a 30amp circuit? I calculated 4 each with fans and a 20% buffer. This seems really low and problematic. What are my other options? What have other miners done to overcome these challenges? Do I really have to hire an electrician to install a dozen 30amp circuits and run new outlets to my server room in order to run more machines?

Thanks!

I think it is recommended to stay at or under 80% on each circuit for 24/7 operation. I have had no trouble with my 11 amp rig running on a 15 amp circuit for about a month now non-stop. I still got renters insurance though ;P

116V? Uh, standard is 120V afaik, unless you live in some other country?

How many machines you can run depends on the machine itself, need more information. If your building only has 100amp service than adding more circuits won't help at all.

Anyway, I'm going to assume 120V despite your claims, and as such 120V*30A = 3600W / circuit. Assume a 4x5870 system + cpu = ~1000Watts from the wall, that's 3 systems per circuit.  Most circuits are not 30A however, but if you can get that cool. Why 30A though if you are customizing it yourself?

Yeah that's why I put (killowatt) in there. The math doesn't work out so I don't know if the meter is wrong or if voltage fluctuates by a small margin. I assume both are an issue in the measurement.

Either way, it's 420W, 5.35amps. From what I understand one of those measurements is wrong too (W=A*V, I thought) so I took the higher of the two (amps) and:

5.35amps * 4 = 21.4amps
30amps * .8 = 24amps
so that leaves 3amps to run fans for 4 machines. I'm looking for any information about what I might be missing or overlooking / how others have overcome this challenge.

Thanks!

A standard circuit is 20 amps not 30 amps, 30 requires upgraded wiring specs if I am not mistaken. If your house has homerun outlets or you can run new homeruns to your circuit breaker you should have 20amp circuits and plug 3 machines per breaker in.

If you're buying new breakers and wiring them in, you should buy 15amp breakers and only run 2 machines per breaker (then you can use a standard outlet per circuit), you're confident about not overloading the circuit, and you're not wasting anything other than circuit breaker slots.

If you can install as many circuits as possible you shouldn't worry about max per circuit you should just be safe and go for the 2 machines per 15 amp circuit route, and worry about maxing your 100amps of power.

Thanks, very helpful! This adds a lot of cost to the operation :(

sidenote: I saw your post here: http://forum.bitcoin.org/index.php?topic=9239.20 - did you ever figure out how to overclock your GPU clock beyond it's 'cap' like all the windows users are reporting?

*I was actually about to send you a PM about the overclocking. I went to read through your old posts to see if you mentioned a solution and saw this one at the top :\ weird

Due to this thing called Ohm's Law <http://en.wikipedia.org/wiki/Ohm's_law>, the measured voltage at an outlet is never exactly 120 volts.

And as mentioned earlier, 20 amp circuits are normal, and should not be run above 80% (16 amps) continuous, so plan on 16 amps usable. So 3 systems at 5.33 amps per system, per circuit.

Whatever you do... do not just install a larger breaker without upgrading the wiring. The breaker protects wires from overloading/heat buildup from that and causing possible fires.  larger breakers require larger wiring.

Make sure the wire has the right Amp rating or it'll start to melt. the right watt rating so u know the voltage it can carry. Or the insulation will break, potential short circuit. The breaker is just there to protect both ends when the load is trying to draw more amp than the designed, however when u change the breaker u change the design, which includes the wire.

As for wall sockets, the voltages 240/230/120/110 are all RMS (root-mean-square) values that is theoretically equal to the D.C equivalent voltage you'll get. It is actually in A.C form and is around √2x 240/230/120/110 Voltage Peak for the sinusoid. (Peak-to-peak is 2x). Depending on your power service provider's quality, spinning reserve, the variance of the load at the consumer's side and other factors, it might fluctuate from time to time. Especially when the service provider is trying to skim on design.

EDIT:
Anyway, you're doing the right calculations and taking the higher to be safe is the right way to go. But don't forget about other parts of the system or get a licensed technician/electrician to change the thing, shouldn't cost more than $80 to get the layout and a few dedicated sockets that would provide higher amp/watt for such applications.

This... is the first thing I thought of when I ran into electrical bottlenecks.

I quickly realized that this was not possible/safe/recommended by anybody.

Thanks for the advice and information everyone. I'm meeting with an electrician in a few hours and now I know what I need.

Whateve it is, it will be problematic.

Your wiring, your huse upink, the street upklink are all possible bottlenecks that will come one by one.

You need industrial power ;)

heck, I am now looking for a room where I can get 300 kw. Renting something in some industrial complex ;)

Housing areas may not have the reserves you need at all. Mixed areas will. Be lucky where you live. Your wiring will only be the first bottleneck ;)