Bitcoin Forum

With a standard 100 amp residential supply my consumer unit is split up with a number of RCD's.

My garage which hosts all my mining equipment has an RCD of B40 (I assume that's 40 amps), on the main board, with an RCD in the garage too.

Does this mean the totality of my miner consumption must not exceed 40amps, calculated as PSU Watts/240V.

For example if I have an Antminer S4, which has a 1.4kW PSU, this is consuming 5.8amps? Therefore I can only have 40/5.8 = 6 S4's on this RCD?

Or is the consumption and the RCD related in a different way.

The reason I ask is that if was to bulk buy the 16 S4's from Bitmain (ignore ROI for now :)), I would need effectively 4 B40 RCD's?


Have I understood that correctly?
Thanks
Rob

What country are in? Most newer homes in the United States have a 200 amp residential panel. The circuit breakers in the panel are generally rated 15 to 20 amps and are shared by one or two outlets.  16 S4 at 1400 watts per S4 you are looking at 22,400 watts.  No way you can run this many S4's with only 100 amps.

I'm in the UK
Homes here have a standard 100 amp supply, with 240V wall sockets.

I'm not expecting to be able to run them all, but just wanting to confirm my understanding in terms of what the RCD rating allows. As the total of all the RCDs in the panel exceed 100amps.

What's an RCD?

http://en.wikipedia.org/wiki/Residual-current_device

if it helps, picture of board here:
https://i.imgur.com/0fvNwY7.jpg

1.4 kW will pull about 5.8 amps at  240v so you are safe to put 5 maybe 6 on your circuit. How many outlets are you sharing on the circuit? To add more you would need to upgrade the panel to 200A then you could add 2 more 40A RCD's. Also I would spread the amps over multiple outlets because the wiring in one outlet is probably not sufficient to handle 40A.

Almost. You shouldn't run a circuit above 80% continuous. So keep your 40 amp circuit at 32 amps or less. 32/5.8 = 5x S4s.

That may explain why I have a 32 amp breaker in the garage on that circuit.

Thanks for your help. It confirmed my thoughts and then some.

Regards
Rob

Your garage supply not using RCD, it's MCB  :)
It's seem connected directly to main switch, not through 80A RCD. Can't be sure unless you can open the cover & take more detail picture  ;D

But still, the maximum you can pull is 100A minus other load on RCD.
Example, if load on RCD already 70 A, then maximum load is 30A

You should NOT give electrical advice assuming that the UK electrical circuits are similar with your US ones. Please, for heaven's sake .. grow up .. or the OP will need a new home soon. The only similar thing is that they have plugs .. see an example below:

http://upload.wikimedia.org/wikipedia/commons/thumb/8/81/Consumer_Mains_Wiring.jpg/640px-Consumer_Mains_Wiring.jpg

Interesting. Tell us more. Do you suggest running a UK 40 amp circuit at higher than 80% continuous load 24/7?

I am running Antminer S4. If the voltage from the mains is a perfect 230V, then it will take 6.2 A at the wall.

No. I suggest trying to refrain giving advice when you have no clue  (or only assumed clues) of the actual circuit setup in a country with different electrical codes than yours.
There's only ONE RCD in the picture. The things labelled B40, B32 B20 etc are NOT RCDs. There's a reason why this profession is regulated.

That diagram seems to show both a neutral and a ground. Both exist in the UK? Don't they use a delta configuration for most of EU to save copper? Are both supplied by the sub-station?

[braces for rant]

So what does your electrical code specify for the maximum continuous load on a 40 amp circuit?

It's not about what the Canadian code specifies and when. How do you know it is a 40 amp circuit? He has a 100A main breaker and if you add every number you see in the picture you get way more than that (162, right?). Did you ask what other loads he has in the house?  The RCD is good up to 80A for his whole house (except the garage), which leaves only 20A for the garage. I hope she still wants to live there ..  the rest of the house still needs enough juice for the oven, boiler .. etc. He'll trip his pants out, or do some "arc-welding" in that panel if everything start at once, as after a temporary blackout or mains disconnect.

Maxing out a 40amp circuit (as per your understanding, with 32A continuous) when that circuit is not there might burn his garage out. The issue here is that you started giving advice based on what you think he has on in there .. and if he follows your advice he might burn his house down. I wonder how you can sleep at night ..

Yes. Neutral and ground are separate.
No. Delta is not used at low voltage. The final service voltage is 230/400V wye.  In Uk, most residential is single phase 100A @ 230V. Large residences and small commercial premises will usually have 3 phase 100A @ 230/400V.

Whether both neutral and ground are supplied by the sub-station depends on the type of service and cabling.
TN-S (separate earth supplied by substation), TN-C-S (combined neutral/earth supplied by substation, with redundant earthing in transit and separated at point of service drop) and TT (no earth connection provided by substation, customer provides earth rod at service entrance) are all common.


Maximum continuous load on a 40A circuit is 40 A. No derating is required for load duration (doesn't stop it being a good idea), and in general is not performed. For example, no specific derating is needed for a 3.1 kW storage heater which is designed to take full load for 7 hours to charge it's thermal store, and the closest circuit capacity available (16 A) can be used. Typical installation cable is 1.5 mm2 flex (for final connection) and 2.5 mm2 in-wall wiring (derated due to thermal insulation).

Derating is performed based upon ambient temperature, cable grouping, cable mounting surface and insulation.

To me it looks like he's got 100A for the whole house, 40A breaker for the garage and 80A for the rest of the house.  Wouldn't that allow up to 40A (at 230v = 9,200Watts) in the garage (if at full load, that would leave 60A for the rest of the house) or 80A for the rest of the house (leaving 20A for the garage).  If it goes over 100A for both then shouldn't the main 100A breaker flip?  So he should be able to use up to 40A in the garage, as long as his rest of the house load isn't over 60A?  If it goes over, shouldn't the main 100A breaker flip and then no the house wouldn't theoretically burn down?  (wh00per, that's a question mark there just in case you're not sure I'm asking a question).

Yes. That's basically correct. He's limited by the 100 A service (fuse, not circuit breaker).
His "in house" consumption is limited by the 80A rating of the RCD. However, if he is drawing substantial power in the garage, then it will be limited by the total load on the 100A main switch and fuse.

So, if he exceeds 100A, he will blow out the sealed service fuse, and then have to call the power company to come out, unseal it and replace the fuse and reseal.

The big problem he has in his house is the electric shower. As this has a 50 A dedicated circuit, this suggests that it is a 10.8 kW shower (45A operating load). That is a big load, and once you add lighting loads, kitchen loads, etc. a 40A mining load is starting to look infeasible.

One option is to upgrade the supply from a 230V (23 kW) supply to a 230/400V (70 kW) supply. If he asks his electricity supplier they will quote on the price of an upgrade (usually it's around £2000-£3000), and it'll be another £500-800 for an electrician to replace the fusebox with a 400 V one + another £few hundred for additional circuit installation. In reality, this probably isn't an economically viable option.

being a sparkie and all i might as well give some advice for you mate.  ;)

first of all what type and size of cable you got running into your garage? is it grey twin&earth throught your house or an swa that is routed underground? also tell me how many metres it is? you are obviously dont want to be having a cable getting too hot. take a picture of your incomer head and size of your main fuse too if possible.

I agree. I would have considered the upgrade as a longer term investment in mining equipment, but the noise alone of having all those miner humming away may upset the neighbours. With the 4TH currently running (Avalon4 and S3's) it is already noticeable.

I think my basic understanding still holds. I am limited by the 100A across the whole house. The fuse rating are essentially peak values, and not what you can throw at the all simultaneously.

BTW there is another RCD on the right hand side of the panel rated at 63Amps (with another 50amp shower supply) - not that we use both showers at the same time, due to water pressure issues.

It's probably safer to invest the £2k in more miners and a dedicated remote hosting solution.

grey 6mm T&E from Consumer Unit to Garage, about 25m run
sockets are running 2.5mm cable on a Ring

main is 40amp. Sockets running off 32 and lights off 6

https://i.imgur.com/01sBRwM.jpg

you can basically have 32a mining in the garage running constantly on 2.5mm ring. but your 6mm 25 metre run can only handle no more than 34a. plus you have a bit of voltage drop. if your antminers leak current over 30ma then your rcd might trip but most probably it wont. you could have another 16mm cable running there supplying two 32a breakers for 2.5mm rings or 4mm radial circuits. though then you need to see your incomer cable size as you might reach overcurrent limit while having a shower on or a kettle etc. if i were you i would just leave it the way it is. just make sure your antminers dont take more than 30-32a.

1400w psu is given with some headroom, though you also have to add inefficiencies.
typical voltage in uk is 240-245v.
1400w/245v=5.71a.
32a/5.71a=5.6

so you can only have 5 of them hashing there im afraid - 5 more if you bring 6mm 32a cable into garage. or 6 more if make it 10mm 40a (you'll need 4mm ring for that). anything more you risk to overload your incomer. though i need picture of it as some big houses sometimes have two or three phase supply coming in but only one is used. also constant current demand might attract the piggies through infrared 'copters as they'll see that your shed is always hot thinking you grow some score.

hope that helps.

Thanks for quality answer! The diagram had 3 phases and residential appliances and thus I naively wondered if those epic 100 amps in the UK were supplied by 3 phases to every home.

:) Yes. I'm already waiting for it to snow this winter.
Thanks to all for the advice. I'll ponder over christmas before stumping up 5 S4's worth of cash. Especially with the falling BTC price at the mo.

Rob