Hi again,

Should have asked this as part of my previous circuit breaker question, but
forgot:

Is it common or typical for an "old" house service box circuit breaker
(perhaps 25 yrs old) to go bad,
and trip by itself, even if there is nothing wrong with the circuit it is
controlling ?

What's a "typical" life for these things ?

Thanks again,
Bob

"Robert11" wrote in message
...
Hi again,

Should have asked this as part of my previous circuit breaker question,
but forgot:

Is it common or typical for an "old" house service box circuit breaker
(perhaps 25 yrs old) to go bad,
and trip by itself, even if there is nothing wrong with the circuit it is
controlling ?

What's a "typical" life for these things ?

Thanks again,
Bob

A lot of older Murray brand will do that. The internal latch that holds the
handle in the on position, just stops holding and vibrations can cause them
to turn off

On Apr 8, 8:13�am, "Robert11" wrote:
Hi again,

Should have asked this as part of my previous circuit breaker question, but
forgot:

Is it common or typical for an "old" house service box circuit breaker
(perhaps 25 yrs old) to go bad,
and trip by itself, even if there is nothing wrong with the circuit it is
controlling ?

What's a "typical" life for these things ?

Thanks again,
Bob

yes it is............ breakers are designed to become more sensitive
as they age, and its more common for a breaker to become super
sensitive if its on a heavily loaded circuit.

theres no set life. but do replace the questionable breaker

wrote:
....
...breakers are designed to become more sensitive as they age, ...

Have you any reference from a manufacturer that is a design criterion?

Don't say it isn't so, but I've never heard or seen it mentioned in any
literature which one would think would be so if were an actual design
feature.

I just did a search of the entire product brochure for the Square D QO
breaker series and there's no mention of "age" or "aging" or
"sensitivity" throughout.

--

On Apr 8, 10:24�am, dpb wrote:
wrote:

...

...breakers are designed to become more sensitive as they age, ...

Have you any reference from a manufacturer that is a design criterion?

Don't say it isn't so, but I've never heard or seen it mentioned in any
literature which one would think would be so if were an actual design
feature.

I just did a search of the entire product brochure for the Square D QO
breaker series and there's no mention of "age" or "aging" or
"sensitivity" throughout.

--

hey when there trying to sell you something NEW they dont mention
againg might hurt sales.......

dont have a link of one even exists, but its true of all
breakers.........

a matter of liability, as it ages it has to change.

I repair office machines for a living that draw lots of current.

customer complains its tripping breaker, replace breaker trouble gone
provided circuit isnt overloaded.

some machines i service have breakers built in, and they fail
sensitive.

breakers trip from heat, my theory is contacts degrade a little, heat
and make things more sensitive.

I used to spend a couple days a month at westinghouse beaver, breaker
manufacturer. back before it was sold off, a fascinating place. nice
friendly folks, who told me more than i really wanted to know about
breakers. i tended to have lunch with the engineering group who were
the first to talk about more sensitive with age.......... had a bunch
of machines in engineering.

wrote:
....
hey when there trying to sell you something NEW they dont mention
againg might hurt sales.......

Like somebody isn't going to buy a breaker because there's a data sheet
that shows it's 20-yr future sensitivity--right.

dont have a link of one even exists, but its true of all
breakers.........
....

If it were a serious issue (which theoretically it would be if
sensitivity were to go the other way) in the spec's I'm quite sure it
would be addressed in the design phase. (And, I'm _QUITE_ sure the
major manufacturers do significant aging studies.)

--

On Apr 8, 10:54*am, dpb wrote:
wrote:

...

hey when there trying to sell you something NEW they dont mention
againg might hurt sales.......

Like somebody isn't going to buy a breaker because there's a data sheet
that shows it's 20-yr future sensitivity--right. *

dont have a link of one even exists, but its true of all
breakers.........

...

If it were a serious issue (which theoretically it would be if
sensitivity were to go the other way) in the spec's I'm quite sure it
would be addressed in the design phase. *(And, I'm _QUITE_ sure the
major manufacturers do significant aging studies.)

--

This doesn't apply to residential, but the large industrial building
where I work is having the main breakers replaced in the near future.
The only reason I know about this is that obviously the power will be
out for the duration of the replacement, and they have warned all of
the building tenants. Apparently there is some rule about replacing
main breakers in industrial and/or commercial buildings at 5 year
intervals.

Ken

Ken wrote:
....

... Apparently there is some rule about replacing
main breakers in industrial and/or commercial buildings at 5 year
intervals.

I'd guess it's something different than just a 5-yr interval...

--

"dpb" wrote in message ...
wrote:
...
...breakers are designed to become more sensitive as they age, ...

Have you any reference from a manufacturer that is a design criterion?

Don't say it isn't so, but I've never heard or seen it mentioned in any
literature which one would think would be so if were an actual design
feature.

I just did a search of the entire product brochure for the Square D QO
breaker series and there's no mention of "age" or "aging" or "sensitivity"
throughout.

-

From my empirical information I'd agree that breakers become more sensitive
with age, at least ones that routinely control loads close to their rated
limit, but I've never heard or read that it was by any kind of design. Just
more unsubstantiated blather Haller pulls out of his ass

I was / am an electrical engineer for 40 years before retiring, and have
never, ever heard of such a design which is deliberately engineered to
become more sensitive as it gets older. This concept for a circuit breaker
is pure nonsense in my opinion.

Smarty


"RBM" wrote in message
...

"dpb" wrote in message ...
wrote:
...
...breakers are designed to become more sensitive as they age, ...

Have you any reference from a manufacturer that is a design criterion?

Don't say it isn't so, but I've never heard or seen it mentioned in any
literature which one would think would be so if were an actual design
feature.

I just did a search of the entire product brochure for the Square D QO
breaker series and there's no mention of "age" or "aging" or
"sensitivity" throughout.

-

From my empirical information I'd agree that breakers become more
sensitive with age, at least ones that routinely control loads close to
their rated limit, but I've never heard or read that it was by any kind of
design. Just more unsubstantiated blather Haller pulls out of his ass

Smarty wrote:
I was / am an electrical engineer for 40 years before retiring, and have
never, ever heard of such a design which is deliberately engineered to
become more sensitive as it gets older. This concept for a circuit
breaker is pure nonsense in my opinion.
....

That's what I think, too...

I can see there being an issue of a sizable _de_-sensitization w/ time
if there were some physical process going on in the bimetal or similar,
but I'd be quite certain if it ever was an issue it has been resolved
long ere now...

--

It's entirely possible that some aging process makes a breaker more
sensitive, less sensitive, totally nonfunctional, etc. Such is the nature of
any design, man made or otherwise. Things change as they age. I just wanted
to make the comment that a deliberate electrical design to become more
sensitive as time passes is not even slightly, remotely possible for a
circuit breaker.

Now, if you wanted to argue that Detroit's engineers design shock absorbers
that are deliberately designed to age in such a way as to have less shock
absorption, then that is a whole different matter.........

Smarty



"dpb" wrote in message ...
Smarty wrote:
I was / am an electrical engineer for 40 years before retiring, and have
never, ever heard of such a design which is deliberately engineered to
become more sensitive as it gets older. This concept for a circuit
breaker is pure nonsense in my opinion.
...

That's what I think, too...

I can see there being an issue of a sizable _de_-sensitization w/ time if
there were some physical process going on in the bimetal or similar, but
I'd be quite certain if it ever was an issue it has been resolved long ere
now...

--

another device thats designed to fail in a benign way are cal stat
thermostats. they are designed to go lower than their design
temperature as they age.

in 30 years of using them for my job i have only ever seen one fail
hot, while i have replaced a couple hundred that failed low...........

for liability reasons no one wants something that when it ages its
dangerous

"dpb" wrote in message ...
Ken wrote:
...

... Apparently there is some rule about replacing
main breakers in industrial and/or commercial buildings at 5 year
intervals.

I'd guess it's something different than just a 5-yr interval...


I have worked at a large industrial plant for 20 years and the plant was
built in 1965. As far as I know the original breakers are still in use
except for a few that have failed.
There are breakers from 120 volts at 15 amps to the very large 13.200 volt
main breakers. Nothing gets changed unless it fails or an inferred scan
indicates it may fail.

Ralph Mowery wrote:
"dpb" wrote in message ...
Ken wrote:
...

... Apparently there is some rule about replacing
main breakers in industrial and/or commercial buildings at 5 year
intervals.
I'd guess it's something different than just a 5-yr interval...


I have worked at a large industrial plant for 20 years and the plant was
built in 1965. As far as I know the original breakers are still in use
except for a few that have failed.
There are breakers from 120 volts at 15 amps to the very large 13.200 volt
main breakers. Nothing gets changed unless it fails or an inferred scan
indicates it may fail.

That's been my experience in power plants, paper mills and coal
mines/prep plants as well.

There are some generating plants built in the early 50s w/ much of the
original electrical controls, switchgear, etc., ...

--

On 4/8/2008 7:39 AM spake thus:

breakers trip from heat, my theory is contacts degrade a little, heat
and make things more sensitive.

Ah, so it's another hallerb "theory". We can safely ignore it in that case.


--
The best argument against democracy is a five-minute
conversation with the average voter.

- Attributed to Winston Churchill

On Apr 8, 8:15�pm, David Nebenzahl wrote:
On 4/8/2008 7:39 AM spake thus:

breakers trip from heat, my theory is contacts degrade a little, heat
and make things more sensitive.

Ah, so it's another hallerb "theory". We can safely ignore it in that case..

--
The best argument against democracy is a five-minute
conversation with the average voter.

- Attributed to Winston Churchill

no i report what westinghouse breaker design engineers told me........

they would change with age so they were made more sensitive to trip on
less current than designed........

this was better than starting a fire..

i happened to be there one day when they were testing knock off
westinghouse breakers, made in mexico. looked just like the ones they
produced from the outside.

when taken to 120% of rated current they exploded, a real fireball.
these breakers were high voltage distribution ones

so has anyone found a breaker that wouldnt trip other than FPE stab
lock??

wrote:
....

no i report what westinghouse breaker design engineers told me........

....

You'll excuse me if I wait to hear from the Circle-W engineers directly
what they _actually_ said and see their design criteria...

--

wrote in message
...
On Apr 8, 8:15?pm, David Nebenzahl wrote:
On 4/8/2008 7:39 AM spake thus:

breakers trip from heat, my theory is contacts degrade a little, heat
and make things more sensitive.

Ah, so it's another hallerb "theory". We can safely ignore it in that
case.

--
The best argument against democracy is a five-minute
conversation with the average voter.

- Attributed to Winston Churchill

no i report what westinghouse breaker design engineers told me........

they would change with age so they were made more sensitive to trip on
less current than designed........

this was better than starting a fire..

i happened to be there one day when they were testing knock off
westinghouse breakers, made in mexico. looked just like the ones they
produced from the outside.

when taken to 120% of rated current they exploded, a real fireball.
these breakers were high voltage distribution ones

so has anyone found a breaker that wouldnt trip other than FPE stab
lock??

I've seen breakers of all manufacturers fail. You think Federal is the only
brand that's had that problem. Try Frank Adams or Zinsco. Personally I think
the only difference is that Federal sold more product

so has anyone found a breaker that wouldnt trip other than FPE stab
lock??

I've seen breakers of all manufacturers fail. You think Federal is the only
brand that's had that problem. Try Frank Adams or Zinsco. Personally I think
the only difference is that Federal sold more product

most breakers work when needed

dpb writes:

That's been my experience in power plants, paper mills and coal
mines/prep plants as well.

There are some generating plants built in the early 50s w/ much of the
original electrical controls, switchgear, etc., ...

There's a hydroelectric powerhouse near hear that was built in 1912 and
remained in use until the late 1990's. Then a new powerhouse with more
efficient turbines came online, and the old powerhouse was turned into a
museum. All the original switchgear still seems to be there, though it
was adapted for remote monitoring and control at some point.

There are a few photos he
http://www.bchydro.com/recreation/ma...nland5361.html

It was built in a time when there was no power grid in the area, so it
was designed to be able to start "cold", with no outside source of
electricity. A bank of lead-acid batteries provided initial power,
probably for instruments and DC generator field. There are a pair of DC
generators, driven by tiny turbines, to provide DC armature power to the
main alternators. Output voltage control seems to have been done with
*large* carbon rheostats in the DC supply to each alternator.

The washrooms look like they are 1912 vintage, too...

Dave