RE: DATACENTER: power requirements

["Dave Greer \(Gnc\)" <dave-greer@gnc-hq.com>]

In any event, it probably doesn't matter. If you are going into a colocation
scenario and they sell you 100A, I'm sure they're not going to say if
you can prove you only use 90A, we'll discount you. I think colo pricing
is pretty static in that respect.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<,

Marty,

As has already been pointed out the Amperage of a circuit is the MAXIMUM
load that it will carry before flipping the breaker or blowing the fuse, it
is not a constant load.  Plus add in the comment made about devices taking
more power to startup, and you are playing a game with no way to win.  Don't
forget to figure in when someone attaches some little device (cell phone,
lamp, clock / radio)temporarily to the circuit and causes you to exceed the
capacity.

Don't laugh, I have seen situations where a technician has plugged in a
laptop which caused an overload and flipped the breaker causing a production
outage at the center of a large corporations network.

The amperage of a circuit is much like the speed of a communications link.
Just because you might have a 100 Mb/s fast ethernet card installed to the
router doesn't mean that you are constantly running 100Mb/s of traffic to
that router.  You just will just have problems as you approach that limit,
and you can not exceed that limit.  In fact we have some routers that will
probably never see 100 Mb/s on a link, but to eliminate problems we run it.

I don't ever like to have more than 60-70% load on an electrical circuit to
allow a little extra for startup.  That being said, I also like dedicated
circuits for large devices such as MMAC's and 75xx series routers.  It costs
a little more but the minimal cost is made up by the reliability of my
network.


Dave Greer