Re: Why deliberately shorting equipment to blow breakers might be a bad idea . . .

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Fri, 12 Jan 2007 01:03:28 -0500, "Robert Green"
<ROBERT_GREEN1963@xxxxxxxxx> wrote in message
<HuKdnVSJx5hwuTrYnZ2dnUVZ_rPinZ2d@xxxxxxx>:

>I can't recall whether it was here in CHA or in alt.home.repair (hence the
>crosspost) but I am certain 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, the report
>staid. The fire marshal said the home did not have sprinklers. The report
>was obtained by The Associated Press under an open-records law.

Sounds like untested hypothesis used to fuel conjecture.  (See below ;-)

Quote: "The wiring MAY have become overloaded" hence "blow[ing] breakers
MIGHT be a bad idea (my emphasis).

A literal reading of the NYTimes article does _not_ indicate that the fire
was shown to be caused by tripping a breaker in my opinion. The information
provided is insufficient to know what actually happened. I'd need much better
information before making any inferences from this vague description.

http://www.townhall.com/News/NewsArticle.aspx?ContentGuid=82c6c40b-62ea-4e5b-9e7c-6a54a9fe707d
	" The Nov. 27 fire at the Anderson Guest House started in the attic
and swept through the one-story building. State fire officials cited an
electrical short or overload as a possible cause. "

 "The facility had been cited for failing to conduct an annual fire
inspection in 2000, but had not been cited for fire problems in more recent
years. The three other facilities run by the same company all had received
fire safety citations since 2003."

Based on only the information provided, it is  possible that _nothing_ that
the worker did had _anything_ to do with starting the fire -- much less
popping the breakers.  The furnace (which is itself a mechanism for creating
fire) was broken _before_ he started and the article is mute on even whether
that was fixed.

Or the worker may have jumped or shorted out a furnace component such as an
SCR, and _also_ popped the breaker with the latter having nothing whatever to
do with causing the fire.

If the worker shorted out or interconnected components or wires in an
electromechanical system, even temporarily, he may have damaged something
creating the hazard in that way. He was, it is written, trying to repair a
furnace, which has motors and relays and sensors and burners that themselves
create fire.

I recently discovered that the single control on my downstairs heating system
that turns the burners off if the boiler gets too hot is a single
thermostatic mercury switch on the hot water pipe leaving the boiler. If the
circulation pump were to fail AND the mercury switch failed, the gas burners
would _never_ turn off because the thermostat would continue to call for heat
and the 80,000 BTUs produced by the boiler would not be removed by
circulating the water so the house wouldn't heat.

Moreover, the circulating water goes only to a heat exchanger in the air
handler. So a similar problem could be created if the multi-stage thermostat
(heat pump,  boiler, or heat pump + boiler)  was inappropriately programmed
and the lone thermostatic switch failed. I discovered during the programming
of a communicating two-stage heating thermostat that in one possible mode,
the only thing between normal temperatures and an overheated boiler *was*
that single heat-actuated switch!   (I've added a second switch to my own
setup as is required -- I've been told -- by commercial at least some
residential codes .)

So if the existing problem the worker was trying to fix was (eg) a bad pump,
and the added problem he caused (or not) was  stuck overtemperature switch,
the combination (as in my case) could itself cause a fire -- especially if
such a system were in an attic (as in the case cited) surrounded by squirrel
nests or leaves or stored items or other flammable items. Or not ;-)


... Marc
Marc_F_Hult
www.ECOntrol.org