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Mining/Folding GPU power efficiency and 230/240V AC and PDUs?

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crashtech

Diamond Member
Jan 4, 2013
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The breakers boxes in the US have staggered bus bars with a separate leg on every other breaker position. The three wires that come in are the secondary of a transformer that makes 240V but there's a neutral wire as a center tap. So if you combine two bus bars by using the double pole breaker, you are using both legs and get 240V as a result. For most household devices, one leg is run with neutral to get 120V. In the UK there is already 230V, so I am not sure what the double pole breaker is for there.
 

Markfw

CPU Moderator, VC&G Moderator, Elite Member
Super Moderator
May 16, 2002
21,404
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136
The breakers boxes in the US have staggered bus bars with a separate leg on every other breaker position. The three wires that come in are the secondary of a transformer that makes 240V but there's a neutral wire as a center tap. So if you combine two bus bars by using the double pole breaker, you are using both legs and get 240V as a result. For most household devices, one leg is run with neutral to get 120V. In the UK there is already 230V, so I am not sure what the double pole breaker is for there.
I was trying to find pictures of an empty breaker box to describe exactly what you said, but I could not find it.
 

Ken g6

Programming Moderator, Elite Member
Moderator
Dec 11, 1999
15,427
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Holy crap, Ken.....That is a first for me, 120v only in the US of A..... 240v optional, but not utilized....wow. Is this for the whole house, or are you perhaps renting only the upper or lower floor? edit: This is personal info, feel free to decline answering.....
Whole house. This place is a (natural) gas (powered house)! ;)

Edit: so is this a house ? and what country is this in ?
Colorado, USA

It's some kind of subpanel, there's no main shutoff evident.
Hm, you're right. There's a main shutoff box outside, on a pole with the electric meter. Last I looked it had a padlock I didn't have a key to.
 

crashtech

Diamond Member
Jan 4, 2013
9,781
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...Hm, you're right. There's a main shutoff box outside, on a pole with the electric meter. Last I looked it had a padlock I didn't have a key to.
Well, I would hope that the padlock does not prevent one from using the disconnect in case of emergency! I think that is probably illegal, if so!
 

VirtualLarry

No Lifer
Aug 25, 2001
51,291
6,551
126
Ok, the Tripp-Lite ("rack-mount", "metered") 240V 20A PDU arrived. I plugged it in with a "SF Cable" branded NEMA 6-20P to C19/C20 12GA (14GA? It was pretty heavy-duty) cable, between the wall and the PDU's upstream C19/C20 connector, and then used a few C13 to C14 or vice-versa cables between the PDU's "normal" outlets, and the two server PCs. I only have two C13 to C14 cables thus far, so I couldn't plug in the PC on top into the PDU yet.

Both servers are showing 5A total on the PDU's meter. (5A x 240V = 1200W??? I guess that's right. 725W + 540W = 1265W on 120V).






 
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