Want to move to all 208V for server racks

Gary Buhrmaster gary.buhrmaster at gmail.com
Fri Dec 3 15:24:21 UTC 2010


On Thu, Dec 2, 2010 at 22:39, Seth Mattinen <sethm at rollernet.us> wrote:
...
> Arc fault breakers are a very new code requirement which I believe is
> primarily targeted at sleeping areas. My place has them (built about 4
> years ago) on the bedroom outlet circuits. If I spin the socket switch
> on one of the table lamps too fast it'll trip.

The NFPA priority is to protect life (property/equipment
are there too, but lower in priority).

(Note that while NFPA 70 is not required, most
jurisdictions eventually turn it into their law/codes.
But exceptions exist, and your specific requirements
may vary, and not all jurisdictions adopt the new
rules immediately.  Some still (only) require
NFPA 70-2005, and not NFPA 70-2008.  There is
no known case where applying more recent
practices has resulted in liability, so some
contractors may build to 2008 when only 2005
is being enforced by the inspector).

Now that most outlets are grounded, and GFCIs are
in locations where people are likely to be the source
to ground ("wet" areas), one of the bigger remaining
issues for loss of life in the home due to electricity
was in the bedroom with arcing between the hot/neutral
when people were asleep (and could be overwhelmed
by the smoke before they could get out of the house).

Another addition to the code a few years ago was
what I call "child proofing" the outlets(*).  You will
see all new (but not existing old stock) outlets having
a (usually) mechanical cover for the slots which requires
a plug to be pushed in (only the pressure from both prongs
will open the cover) to protect against the inquisitive
fork or finger problem.

NFPA 70 does take into account industry recommendations
(for the conspiracy theorists), and the perceived return
on the costs (something that saves 1 life over 10 years
but costs billions is not likely to make it into "code").

Gary

(*) Technically, I think these are called Tamper-Resistant
     Receptacles, and are required in all new work as
     of NFPA 70-2008.




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