[Beowulf] Quick question...

Larry Stewart larry.stewart at sicortex.com
Sat Mar 17 10:20:49 PDT 2007


Robert G. Brown wrote:
> 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
> short.
>
> 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".
>
>    rgb
>
The code says that a single receptacle on a circuit must have a rating 
at least
as high as the circuit breaker, so you can't change the receptacles to 
L5-20R's
unless you change the breakers too.

Here's an adapter that does what you want.

http://www.stayonline.com/detail.aspx?ID=3105

Counting labor, it might be cheaper than rewiring the cords.

-L





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