If you can use multiple independent circuits each going to a seperate breaker, then that's always the best case.  If you are drawing 20amps, I personally would want that on a circuit that has a 30amp max to be safe.  This is all assuming the wiring in the walls are up to spec as well and were properly installed.  Some caution should be taken to monitor the circuits to ensure they are not overheating/overloading.  Generally if there is a 20amp breaker on a circuit it should be able to handle 10-15amps as long as you're not spiking higher.  Some algorithms and mining software can cause spiking of power outputs so you need cushion in there.  Take things slow and be thorough . . . fires can absolutely occur by overheating improperly setup wiring.

Jake

Whats the memory requirements for mining Zcash? I was trying to get my old 5850 1 GB to do a few sols in wait for my newer card to arrive but the driver crashes and mining never happens.

Well, i dont think that its only metter of fuses , there is limitation of wires thickness in the walls . You just cant put 50Am fuse and load you outlet with 11-12 Kwatt. Wires will be hot and may damaged. Ive  read on some forums that maximun safe load in that case is 4-5 Kwatt on single outlet, 11Kw - whole apartment

I think in case of using one fuse 10A to protect one room you can hold 2 rigs 1250 W each in this room. 16A fuse - 4000W . But its max load of fuse. A little more and it will go off.

if you have different fuses for each room , you could load each room  accrording to calculation above.

If you want all of the rigs in the same room , you probably need to contact your electrician/wireman.

Theoretically, any normal room should have 2 circuits, one for the airconditioning unit and the other one for your light fittings etc.

Now lets say you want to run 5 rigs. You woukd probably need in total 3 circuits in your room. 1 circuit can easily run 2 rigs.

Hello
This week I'm going to buy 2 new rig and I have some doubts.
I raise 2 options.
option 1:
7 GPUs Sapphire Radeon NITRO + Rx 470 4GB (I still do not know if I change for the 480)
1 PSU EVGA 1300 G2
24 m h x7 = 168 mh s in ETH 250 h s x 7 = 1750 h s in ZEC
option 2:
7 GPUs SAPPHIRE NITRO Radeon R9 Fury 4GB
1 PSU EVGA 1300 G2 for 4 GPUs
1 PSU EVGA 1000 G2 for 3 GPUs
28 m h x 7 = 196 mh s in ETH 450 h s x 7 = 3150 h s in ZEC
All reference values are approx. In stock without bios mod.
Mobo: Z170A Gaming Pro Carbon
Processor: Pentium Processor G4500
Memory: HyperX FURY 2400MHz DDR4 Non-ECC CL15 DIMM 8
Currently it is cheaper to buy this mobo than the MSI Z97 Gaming 5 that is difficult to achieve and still supports 7 GPUs
I am in Venezuela, so the electrical or internet cost is not an important factor to take into account.
I would appreciate your opinions for which option to invest and if I should correct or change something.

12.4 has made 1 of my 5 rigs less stable than before, I was on a 300+ hour running streak before the upgrade too!

Yeah I'm not blaming 12.4, sometimes just disturbing a rig can have affects 

The EU server is working well.