Why choose 120 volts?

Joe Greco jgreco at ns.sol.net
Tue May 26 23:30:59 CDT 2009


> On Tue, 26 May 2009, Joe Greco wrote:
> >> Once upon a time, Joe Greco <jgreco at ns.sol.net> said:
> >>> And I don't like not having anywhere to plug in my power screwdriver's
> >>> recharger...  I suppose I should see if I can find someplace that has
> 
> > Yes, but this doesn't imply that you have access to those other phases.
> > It is easy enough to be delivered 208V single phase service in a data
> > center environment.
> 
> Uh.  208v single phase is functionally the same as 240v single phase. 

Yes, functionally, it is.

> You grab 1 hot, neutral off the ground, and you have a common 110v 
> circuit.  Even if you're 3 phase to your PDU, it's still single phase to 
> the servers. (specialty gear excluded, but those generally plug direct to 
> the circuit, not to a PDU).

Go tell your electrical inspector that you're using the ground as a 
neutral.  I'll make the popcorn ...  put simply, that's not allowed,
for Very Good Reasons.

> This makes it very very easy to solve this problem, 

No it doesn't, and the following doesn't even seem to relate:

> and I keep a few of 
> these floating around at all of my datacenters, with big labels saying who 
> they belong too.  (ignoring the fact that for drill charging at least 
> there's usually house power available, but crash carts need these...)
> 
> C14 (M) to 5-15 (F) adaptor cable:
> 
> http://www.cdw.com/shop/products/default.aspx?edc=1036852
> 
> I also use them to run wall warts, etc, as needed.

Great, you're the latest person to invent a way to present a 5-15R that
offers something besides 120VAC.  This is neither new nor novel, but it
*is* dangerous and risky, and in no way "solves the problem."

Plugging a device that is designed to run on 120V into 208V will probably 
result in (at least!) one of:

1) smoke

2) fire

3) burning components

4) dead device

5) burning batteries (in the case of the aforementioned charger)

6) general excitement and panic in the data center in the event that 
   none of the above happen immediately, but rather some time after
   you leave.

7) etc.

The basic problem here is that there are still many devices out there 
that do not have autoranging power supplies.

As for "for drill charging at least there's usually house power available",
well, that sucks.  We're at Equinix.  There are periods where no one uses
the drill, or the power screwdriver, for months at a time.  With 120V in
the cage, I left the chargers hooked up and trickle charging.  Neither the
drill nor the power screwdriver have autoranging power supplies.  So now
with 208V, someone has to bring along batteries, because we can't leave
them on-site, or they'll go stale.  Bleh.

... JG
-- 
Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net
"We call it the 'one bite at the apple' rule. Give me one chance [and] then I
won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN)
With 24 million small businesses in the US alone, that's way too many apples.




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