Possibility of Tripping Breaker

[idothemining]

Hey everyone,

A quick question from a hobby miner: I was just wondering if two underclocked SP20s on platinum 1200W PSUs (pulling 1208 W TOTAL as read from their ASIC stats pages) + an underclocked A2 Terminator (Scrypt miner, probably pulling 700 W at most) would possibly trip a 20 A breaker (2400 W overhead). I know, the first thing I should do is buy a physical watt meter, and it's currently on its way in the mail.

I was just hoping someone out there could help me double check my math and let me know if there are any variables I'm not taking into account. (I know that, in keeping with the miners' PSUs efficiency ratings, the power actually drawn can be expected to exceed that reported in software by 5-10%.)

It looks like, at most, I'd be pulling 2100 W out of the "available" 2400 W, but I'd really appreciate any and all feedback!

Thanks!

[NiHaoMike]

You want at least 20% margin. Best plan is to move one of the miners to a different circuit.

[Flying Hellfish]

IMO get a clamping Amp meter, forget the watt meter.  

Never run a circuit more than 80% of its rated max capacity.  That means your 20A circuit is safe for 16A draw or less.

Your breaker is rated in Amps so measure Amps drawn by the load and you can rest assured you're in or out of acceptable limits.

[idothemining]

Right—I'll hold off on running them all at once until I can get some current readings.

Thanks for the fast replies, lads!

[QuintLeo]

In warm weather, unless your breaker panel is in an area with A/C, you probably WILL pop the breaker with that much load on it.

[OgNasty]

I don't think you'd pop the breaker or have any serious problems if your house is relatively new (assuming it followed US building code). If the wiring is bad your house may burn down, but your energy use won't trip the breaker. I would recommend using a different outlet for each device though, and of course an extension cord from another circuit would probably be the safer way to go about it.

[trinitrate]

Circuits are rated for a given amperage (20A for example) but are not intended to run at that amperage continuously.

When you are sizing circuits for server rooms for example, there is an expected overhead of 20% for each circuit if you will be running the loads 24x7 (like a miner).  This is to help compensate for the heat buildup that would occur in the wire if it was used at full capacity for an extended period.

As was stated above, you should assume a max sustained load of 16A if your usable ceiling.