What MIC should I go for?

Dr Bolouswki

I'm looking to run a computer lab from the house.

Current supply is standard household 63amp.

I want to run 50 computers, each pulling 1000w at 240v at 85% efficiency 24/7. I will also need aircon to keep the room cool. I think likely a 9000w unit (its cooling a room 3m x 5m). The room is a new build Barna concrete shed.

By my calculations, I would need a feed of 250 Amps! (1000w/ PF .85 x 240v)?

Shurely shome mishtake? And if this IS what I need, does that mean I need a new 3 phase feed run out to the shed? So I'm looking at €10k or so setup cost?

Thanks for any help - trying to get an application in for an increased MIC and I don't know what to ask for (single phase, 3 phase, 250kVA?), but it looks like I wont get anywhere close to what I need

Stoner

Very very high level

You've 50 units all taking say 1000Watts so approx over 4 amps per PC and you've 50 so you shouldn't be surprised at your numbers.

How have you calculated your cooling load? it looks light at first glance

Either way it's a three phase supply.

Are you mining ? Does that account for the 1000W per PC at full tilt 24/7. That's high otherwise

2011

Dr Bolouswki wrote: »

I'm looking to run a computer lab from the house.

What do you mean by "computer lab"?

I want to run 50 computers, each pulling 1000w at 240v at 85% efficiency 24/7.

Are you sure these computers are 1 kW each? That is very high, the average desktop would draw around 200 W. See link.

My old Mac mini is a maximum of 85W.

Perhaps you are not using the average computer!

Assuming you are correct, that is 50 kW.

I will also need aircon to keep the room cool. I think likely a 9000w unit (its cooling a room 3m x 5m). The room is a new build Barna concrete shed.

So a total load of 59 kW. Once you add in a few lights and miscellaneous items lets say 60 kW.

Total current per phase for a balance 3 phase load = 60,000 / √3 x 400 x 0.85 = 102 A

So I'm looking at €10k or so setup cost?

Maybe a lot more than €10k or maybe a lot less. It depends on whats involved. Whatever you are doing (Bitcoin mining) would want to be quite profitable to cover this energy cost.

If you were to use 60 kW of power 24/7 at a cost of €0.14 per unit this would cost an average of €6,132.00 per month (not including VAT or standing charges).

Dr Bolouswki

Yep its a mine indeed. Jaysus. I've 14 machines right now and it runs no problem off my apartment supply. Was going to move it to the folks house - avail of a flat rate contract.

So in reality - a 3 phase 100Amp or so is needed if I want to grow to the levels i outlined?

Stoner

Dr Bolouswki wrote:

Yep its a mine indeed. Jaysus. I've 14 machines right now and it runs no problem off my apartment supply. Was going to move it to the folks house - avail of a flat rate contract.

Well 14 machines at over 4 amps (1000W) each is about 60 amps. The apartment would mostly be a 55 amp fuse.
A two bed apartment would normally only run at between 12 to 25 amps again all approx. You should be blowing fuses

I'd say you are over egging the PC load. If you've a few on one "extension" lead pop a plug in power meter on it see the real power requirement

Dr Bolouswki

Really appreciate the replies.

I've used a wattmeter on each machine individually and they vary from 850w to 1100w at the wall.

I have them split evenly over 4 circuits (each apparently capable of 20 amps?) Max load per socket is 2x machines (on a 13amp extension lead). I "borrowed" my heating circuit (storage heating - never used), likewise the heaters for the bathrooms, which gave me two unused circuits off the main board, plus there was a spare circuit there too. The 4th circuit is just the normal plug one for the apartment.

Looks like I may be better off splitting the deployment and having 2x domestic charges, and rein back the growth plans to maybe 30 machines, 15 in each location? I'm guessing MIC increase request of about 45A? Keep in mind the household uses very little - no electric showers or heaters (empty for 6 months a year also).

That formula for 3 phase - is 400 the line to line voltage? Sorry - I'm completely new to anything to do with electricity!

2011

Dr Bolouswki wrote: »

That formula for 3 phase - is 400 the line to line voltage?

Yes, with a 3 phase supply that is the line voltage.
However as you have a neutral each of the required single phase circuits will provide you with a voltage of = 400 / √3 = 230 volts.

2011

Dr Bolouswki wrote: »

I've used a wattmeter on each machine individually and they vary from 850w to 1100w at the wall.

Fair enough.

I have them split evenly over 4 circuits (each apparently capable of 20 amps?) Max load per socket is 2x machines (on a 13amp extension lead).

As these loads are connected all of the time (including when nobody is home) I would prefer not to use a plug / socket arrangement. Instead a safer long term arrangement would be a switched fused spur outlet. This would not be an expensive change.

It would also be preferable not to use extension leads on a long term basis.

I "borrowed" my heating circuit (storage heating - never used), likewise the heaters for the bathrooms, which gave me two unused circuits off the main board, plus there was a spare circuit there too.

Good idea.

Looks like I may be better off splitting the deployment and having 2x domestic charges, and rein back the growth plans to maybe 30 machines, 15 in each location? I'm guessing MIC increase request of about 45A? Keep in mind the household uses very little - no electric showers or heaters (empty for 6 months a year also).

It is all about the load profile.
My advice would be to monitor what load you have in each location at present with a energy meter such as an Owl. This can provide a daily consumption graph so that you can get a really good picture of what is being used.

Dr Bolouswki

Excellent - just got me an energy monitor! Thanks for all the great info