wrote:
Robert Green wrote:
....
...I read messages from people who short outlets or
wiring with a screwdriver (instead of using a meter or a fox and hound toner
set) to find the controlling circuit breaker for that branch. The article
below points out the possible downside of that approach:

Missouri: Inquiry Ties Wiring to Fatal Group Home Fire

http://www.nytimes.com/2006/12/20/us/20brfs-Fire.html

By LIBBY SANDER
Published: December 20, 2006
Hours before a fire killed 10 people in a group home for the mentally ill
and disabled on Nov. 27 in Anderson, a maintenance worker trying to repair a
furnace short-circuited wiring in the attic, where fire investigators said
they believed that the fire started. The worker told investigators that he
did not know which circuit breaker operated the furnace and that he
deliberately tripped the system, according to a report from the Missouri
Fire Safety Division. The wiring may have become overloaded, ...

If everything is "to code", aside from the personal hazard to the one
doing the shorting, this practice should be completely safe.

But the consequences of something being amiss (not to code, poorly done
wiring, etc) and causing a fire, with damage or worse, is too high a
consequence to pay for a little convenience.

Its a classic "low risk of occurrence, high cost of occurrence"
scenario.

Something seems left out here. As you say, unless there's another
fault, there really is no reason this should cause any problem
whatsoever -- how does the breaker or rest of the circuit "know" it was
a deliberate act as opposed to accidental or a faulty piece of
equipment plugged into an outlet or a ground fault developed in the
furnace blower motor? All the breaker was supposed to do was trip to
remove the fault condition. Did it not do so? If it did, how was
there an "overload" in a dead circuit? Was the breaker over-sized for
the branch wiring?

The fundamental fault appears more deeply embedded and the consequence
could just as easily have occurred had there been another causative
action so I think faulting the maintenance worker unless he left an
undersized jumper in place or some other action other than simply
causing the short seems short-sighted -- finding the underlying fault
that then caused the result should be the focus of investigation, not
simply a person to point blame at. Then again, if he was smoking at
the same time, too, and dropped the end of his cigarette in the attice
w/ onto something flammable beside the location he got access to the
wiring to make the short...

In all, I think there's more to the story still untold...