A friend of mine worked as an electrical engineer in an industrial plant.
They checked several different manufacturers' breakers to see if they would
trip as specified. Most took quite a bit of over current (beyond spec) to
trip them. Some more than 400%. If I remember right GE breakers were the
worst.
73
Gary K4FMX
_____
From: Rob & Terri Sherwood [mailto:rob@sherweng.com]
Sent: Friday, October 21, 2005 9:37 PM
To: m.ford
Cc: Gary Schafer; amps@contesting.com
Subject: Re: [Amps] AC wiring
I own a house built in 1925, which was rewired with breakers in the 50s or
60s. When I bought it in 1971, I paid little attention to the FPE (Federal
Pacific Electric) breakers outside in the box. Some of the wiring in the
house is original, #14 or maybe #16, cotton coated, and run in black iron
pipe. Those are breakered at 15 amps, along with #12 twenty amp circuits
and breakers added over time. I found out about breakers that don't break
when a bare bulb light socket in the basement ceiling shorted as I was
trying to install a new bulb. A fireball of sparks started, with melting
copper dripping on the concrete floor. Over at least 15 seconds the socket
played arc lamp, until the wire apparently burned enough to break the arc.
The circuit breaker never blew. After that I did some research on FPE, and
found there were know problems with their breakers not opening under a
serious fault. I had the panel replaced within the month.
73, Rob, NC0B
m.ford wrote:
----- Original Message -----
From: "Gary Schafer" <mailto:garyschafer@comcast.net>
<garyschafer@comcast.net>
To: "'m.ford'" <mailto:k1ern@direcway.com> <k1ern@direcway.com>;
"'R.Measures'" <mailto:r@somis.org> <r@somis.org>
Cc: <mailto:amps@contesting.com> <amps@contesting.com>
Sent: Thursday, October 20, 2005 8:10 PM
Subject: RE: [Amps] AC wiring
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of m.ford
Sent: Thursday, October 20, 2005 11:16 AM
To: R.Measures
Cc: amps@contesting.com
Subject: Re: [Amps] AC wiring
----- Original Message -----
From: "R.Measures" <mailto:r@somis.org> <r@somis.org>
To: "Tony King - W4ZT" <mailto:amps080605@w4zt.com> <amps080605@w4zt.com>
Cc: <mailto:amps@contesting.com> <amps@contesting.com>
Sent: Thursday, October 20, 2005 8:30 AM
Subject: Re: [Amps] AC wiring
On Oct 19, 2005, at 1:13 PM, Tony King - W4ZT wrote:
Seems a lot of folks have opinions and that is a good thing. Perhaps I
am just a little more anal about keeping wires cool (yes, I HAVE had a
house fire). Fortunately it wasn't caused by under sized electrical
service.
The last house fire in this neighborhood was caused by rodents eating
the vinyl insulation on electrical wires. This happened after the new
owner of the house decided to get rid of all the cats living on his 2.5
acres.
I lost everything in a house fire in 1978. Caused by red squirrels chewing
on the newly installed Romex. The arc in the wall was extinguished when
the newly installed circuit breaker welded shut causing the pole pig to
boil.
Had they left the original plug fuses and panel in place the old farmhouse
would still be here. The NEC can spec all the interupting capacity they
want
but plug fuses don't know jack about di/dt and everytime I see another
house
fire I gotta wonder.
Mike k1ern
This doesn't add up. Are you telling us that both your breaker on the romex
line and your main panel breaker welded shut?
Negative. The 20 amp 120 volt romex line breaker welded shut.
The 100 amp main breaker never opened and the 10 kva transformer
happily provided everything it could until it opened. It was to late.
The inside of the wall was on fire. It was dark. Time to go.
It is my understanding that an arc will only self extinguish if
a. The path is made longer (wires seperate)
b. A bigger arc is drawn elswhere (breaker opening)
c. The source is removed (roasted pole pig)
I'll bet that failure mode has been the root cause of a lot of fires.
Any insurance types care to comment?
Mike k1ern
I do agree that fuses are more reliable than breakers. Some breakers are
very far off from what they are stated to trip at.
73
Gary K4FMX
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