[SPAM] [Beowulf] powering up 18 motherboards

Jim Lux jimlux at earthlink.net
Thu Feb 17 21:41:39 PST 2005

----- Original Message -----
From: "Alpay Kasal" <eno at dorsai.org>
To: "'Bari Ari'" <bari at onelabs.com>; "'Jim Lux'" <James.P.Lux at jpl.nasa.gov>
Cc: "'Dean Johnson'" <dtj at uberh4x0r.org>; <beowulf at beowulf.org>
Sent: Thursday, February 17, 2005 9:26 PM
Subject: RE: [SPAM] [Beowulf] powering up 18 motherboards

> I think you hit the nail on the head Bari, I'm in Brooklyn, New York. So I
> suppose it should be 15amp circuits but every circuit breaker in the box
> clearly a 10. This is an old house, seems like any renovations over the
> years have been only for aesthetics. The wiring in the walls is probably
> disintegrating - that would explain why the new looking circuit breakers
> rated for 10 amps.

Ahhh yes.. New York, where some of the (mostly undocumented) distribution
wiring dates from Edison himself, and dogs are electrocuted when urinating
on the street from stray currents in connection boxes.  The wiring is
probably knob and tube.

> I think I can get use of 3 circuits which gives me some room to play with
> all the nodes and hopefully the assortment of switches and power supply. I
> have to figure out what the draw will be on the rest of the equip. Now
> the hell am I going to plug in this air conditioner????
> Any advice on how to gang up 3 10amp circuits into a single 30amp? Sounds
> like a job for an electrician? Thanks for the help guys.

Why gang em up?  Just run three extension cords or plug strips, one into
each circuit. 6 machines on each circuit.  If the startup surge is too much,
stagger the spin up of the disk drives (maybe some sort of BIOS power
management option?).  Seriously think about cobbling together some
collection of relays.   The W.W.Grainger catalog is your friend, even if you
don't buy your stuff from them, you'll at least have a good description to
go googling for surplus places.

If that gets too dicey.. Honda and Yamaha make very nice, quiet inverter
generators.  2kW for about $700.

Good luck...

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