Top-shelf resilience (Re: Why the US Government has so many data centers)

Måns Nilsson mansaxel at
Fri Mar 25 19:54:48 UTC 2016

Subject: Top-shelf resilience (Re: Why the US Government has so many data centers) Date: Tue, Mar 22, 2016 at 07:59:24PM +0000 Quoting Jay R. Ashworth (jra at
> This seems like a good time to mention my favorite example of such a thing.
> In the Navy, originally, and it ended up in a few other places, there was
> invented the concept of a 'battleshort', or 'battleshunt', depending on whom 
> you're talking to.

I've built one, sort of. In an outdoor broadcasting vehicle. See, in
order to get a working grounding scheme, the PDU in the bus gets to serve
as power source for a lot of things that might find themselves outside,
in climate. 200VDC feeds in triaxial cables to cameras, for instance.
(this was before cameras were connected with singlemode fiber, but
after the era of the multicore "shower handle" connectors) All this
was of course built for some exposure to the elements but not for
drenching. During setup, it was decided to protect people with a GFCI
breaker on the main three-phase bus in the bus[0][1], but once setup,
people were not really supposed to gefingerpoken the thingamaboobs, so
in the interest of reliability a bypass was created for the GFCI breaker.
This had to be built in-house, since no electrical contractor even wanted
to contemplate it. So we did.

/Måns, ex-builder of analog broadcast facilities. 
Måns Nilsson     primary/secondary/besserwisser/machina
MN-1334-RIPE                             +46 705 989668
First, I'm going to give you all the ANSWERS to today's test ...  So
just plug in your SONY WALKMANS and relax!!

[0] Pun not intended but carefully kept once discovered. 

[1] This is (continental) Europe, where we are not afraid of 405VAC
    three-phase mains. Tesla was European. Edison was born to American 
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