[Beowulf] Quick question...

Robert G. Brown rgb at phy.duke.edu
Sat Mar 17 08:52:36 PDT 2007

As I'm working up a server room and some UPS's, a question arises.  The
APC units we have have a different plug and current rating from the
circuits in the wall.  In particular, we have L6-30R receptacles and the
APC requires only 20A.  I had thought that it would be perfectly safe to
replace an L5-20P with an L6-30P and plug a 2200 VA UPS into a 30 amp
circuit, but the electrician who was doing some of the rewiring said "we
can't do that" because "the 30A circuit breaker might not blow in time
to protect" the 2200 VA device from damage in the event of an internal

This argument seems quite senseless to me.  If this argument were
correct we could never plug a 15 A device into a 20 A circuit, etc.  It
would really simplify my life if I can just rehead the cable.  Do any of
the electricity-savvy people here have any comments regarding the safety
or legality of doing so?  I have always assumed that going up a size in
circuit capacity is generally safe and legal...

I'm planning to do the rewiring of cables today soon, so if you know
something about his please respond "soon".


Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu

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