Testing GFCI's - A Philosophical Discussion
 

I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. A GFCI is an electromechanical
device and the possibility exists that the test we just performed was
the last time that particular unit was going to work.

Granted, if it fails the test, we know we should replace it, so we're
really checking for a failed device, not a working device. Perhaps we
should feel better (read: relieved) when the test fails, because we
have the opportunity to replace the failed device. Ah, but wait - once
we replace the device and test it, all we really know is that it passed
it's initial test - we still don't know that it will work when it is
needed.

You know that disclaimer the investment folks always use - "Past
performance is not a guarantee of future results"? It seems to me that
the same holds true for a GFCI.

I submit that we should not feel confident that a GFCI will protect us
just because it passed the test. In reality, all we can do is look back
and say whether or not it would have protected us since the last test.

Sleep well!

Testing GFCI's - A Philosophical Discussion
 

DerbyDad03 wrote:

I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. A GFCI is an electromechanical
device and the possibility exists that the test we just performed was
the last time that particular unit was going to work.

Granted, if it fails the test, we know we should replace it, so we're
really checking for a failed device, not a working device. Perhaps we
should feel better (read: relieved) when the test fails, because we
have the opportunity to replace the failed device. Ah, but wait - once
we replace the device and test it, all we really know is that it passed
it's initial test - we still don't know that it will work when it is
needed.

You know that disclaimer the investment folks always use - "Past
performance is not a guarantee of future results"? It seems to me that
the same holds true for a GFCI.

I submit that we should not feel confident that a GFCI will protect us
just because it passed the test. In reality, all we can do is look back
and say whether or not it would have protected us since the last test.

Sleep well!

You test them when you install them and you test them when you have
reason to suspect they have been damaged. Outside of that you don't test
them despite the "Test Monthly" nonsense printed on them. Even in large
commercial buildings with full time on site electricians I have never
seen any GFCI testing. IR scans of distribution panels, regular
tightening of connector lugs, etc., but no GFCI testing.

Pete C.

Testing GFCI's - A Philosophical Discussion
 

DerbyDad03 wrote:
I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. ...

That's true of any device, electrical or mechanical. The identical
condition is true when the truck driver is asked to pull over and do a
brake/air check at the top of a long downhill stretch prior to starting
the descent...or the scheduled test of the Class 1 safety system in a
nuclear power plant, or any other system you care to name.

Testing GFCI's - A Philosophical Discussion
 

There has been research that found that the contacts in circuit
breakers and GFI breakers can fuse together with time and corrosion.
The result is a breaker that may trip at a higher load than rated or
may not trip at all. When you test a GFI, you open the points and the
corrosion effect has to start over. From what I read, you really only
need to trip a circuit breaker or a GFI about once a year to prevent
this from happening.
Brad
DerbyDad03 wrote:
I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. A GFCI is an electromechanical
device and the possibility exists that the test we just performed was
the last time that particular unit was going to work.

Granted, if it fails the test, we know we should replace it, so we're
really checking for a failed device, not a working device. Perhaps we
should feel better (read: relieved) when the test fails, because we
have the opportunity to replace the failed device. Ah, but wait - once
we replace the device and test it, all we really know is that it passed
it's initial test - we still don't know that it will work when it is
needed.

You know that disclaimer the investment folks always use - "Past
performance is not a guarantee of future results"? It seems to me that
the same holds true for a GFCI.

I submit that we should not feel confident that a GFCI will protect us
just because it passed the test. In reality, all we can do is look back
and say whether or not it would have protected us since the last test.

Sleep well!

Testing GFCI's - A Philosophical Discussion
 

Absolutely true.

Tommorrow I'll post my philosophical musings on the taxpayer dollars
spent on those "Trucks Test Brakes" signs. Sure seems like a waste. g

dpb wrote:
DerbyDad03 wrote:
I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. ...

That's true of any device, electrical or mechanical. The identical
condition is true when the truck driver is asked to pull over and do a
brake/air check at the top of a long downhill stretch prior to starting
the descent...or the scheduled test of the Class 1 safety system in a
nuclear power plant, or any other system you care to name.

Testing GFCI's - A Philosophical Discussion
 

So then shouldn't the label say "Exercise Monthly" as opposed to "Test
Monthly"?

Brad wrote:
There has been research that found that the contacts in circuit
breakers and GFI breakers can fuse together with time and corrosion.
The result is a breaker that may trip at a higher load than rated or
may not trip at all. When you test a GFI, you open the points and the
corrosion effect has to start over. From what I read, you really only
need to trip a circuit breaker or a GFI about once a year to prevent
this from happening.
Brad
DerbyDad03 wrote:
I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. A GFCI is an electromechanical
device and the possibility exists that the test we just performed was
the last time that particular unit was going to work.

Granted, if it fails the test, we know we should replace it, so we're
really checking for a failed device, not a working device. Perhaps we
should feel better (read: relieved) when the test fails, because we
have the opportunity to replace the failed device. Ah, but wait - once
we replace the device and test it, all we really know is that it passed
it's initial test - we still don't know that it will work when it is
needed.

You know that disclaimer the investment folks always use - "Past
performance is not a guarantee of future results"? It seems to me that
the same holds true for a GFCI.

I submit that we should not feel confident that a GFCI will protect us
just because it passed the test. In reality, all we can do is look back
and say whether or not it would have protected us since the last test.

Sleep well!

Testing GFCI's - A Philosophical Discussion
 

DerbyDad03 wrote:

Absolutely true.

Tommorrow I'll post my philosophical musings on the taxpayer dollars
spent on those "Trucks Test Brakes" signs. Sure seems like a waste. g

dpb wrote:
DerbyDad03 wrote:
I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. ...

That's true of any device, electrical or mechanical. The identical
condition is true when the truck driver is asked to pull over and do a
brake/air check at the top of a long downhill stretch prior to starting
the descent...or the scheduled test of the Class 1 safety system in a
nuclear power plant, or any other system you care to name.

Perhaps, but I've heard of at least one truck driver who was very
grateful for the sand runaway truck ramp at the end of the slope. Could
have damaged a lot more than his underwear had it not been there. Also
note that those trucks pay a much larger share of the roads maintenance
costs than you do in your car.

Pete C.
(I'll probably be a truck driver eventually, once we've managed to
outsource pretty much every other job...)

Testing GFCI's - A Philosophical Discussion
 

DerbyDad03 wrote:

So then shouldn't the label say "Exercise Monthly" as opposed to "Test
Monthly"?

Not in the lard ass US, where exercise is an obscene word...

Testing GFCI's - A Philosophical Discussion
 

It's probably good to exercise all your valves in your plumbing and
test your GFI's once a year. I test mine at each outlet with a
resistor.

Testing GFCI's - A Philosophical Discussion
 

http://www.codecheck.com/codecheck_r...ctr.html#shock

DerbyDad03 wrote:
I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. A GFCI is an electromechanical
device and the possibility exists that the test we just performed was
the last time that particular unit was going to work.

Granted, if it fails the test, we know we should replace it, so we're
really checking for a failed device, not a working device. Perhaps we
should feel better (read: relieved) when the test fails, because we
have the opportunity to replace the failed device. Ah, but wait - once
we replace the device and test it, all we really know is that it passed
it's initial test - we still don't know that it will work when it is
needed.

You know that disclaimer the investment folks always use - "Past
performance is not a guarantee of future results"? It seems to me that
the same holds true for a GFCI.

I submit that we should not feel confident that a GFCI will protect us
just because it passed the test. In reality, all we can do is look back
and say whether or not it would have protected us since the last test.

Sleep well!

Testing GFCI's - A Philosophical Discussion
 

Pete C. wrote:
DerbyDad03 wrote:

Absolutely true.

Tommorrow I'll post my philosophical musings on the taxpayer dollars
spent on those "Trucks Test Brakes" signs. Sure seems like a waste. g

dpb wrote:
DerbyDad03 wrote:
I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. ...

That's true of any device, electrical or mechanical. The identical
condition is true when the truck driver is asked to pull over and do a
brake/air check at the top of a long downhill stretch prior to starting
the descent...or the scheduled test of the Class 1 safety system in a
nuclear power plant, or any other system you care to name.

Perhaps, but I've heard of at least one truck driver who was very
grateful for the sand runaway truck ramp at the end of the slope. ...

Yep... :)

The ramps on I-40 east near Black Mountain west of Asheville in NC have
always had recent signs of activity when I go by there...

Testing GFCI's - A Philosophical Discussion
 

Instead of replying on list, Chris cluttered my inbox with, amongst
other ramblings,

"Heck, if you're going to worry about stuff, why not worry about the
airbags in your car--you have no way to test those until they're
actually needed..."

I don't recall posting that I was "worrying" about anything. I simply
made some points to start a fun discussion and it appears that I
accomplished my goal.

DerbyDad03 wrote:
I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. A GFCI is an electromechanical
device and the possibility exists that the test we just performed was
the last time that particular unit was going to work.

Granted, if it fails the test, we know we should replace it, so we're
really checking for a failed device, not a working device. Perhaps we
should feel better (read: relieved) when the test fails, because we
have the opportunity to replace the failed device. Ah, but wait - once
we replace the device and test it, all we really know is that it passed
it's initial test - we still don't know that it will work when it is
needed.

You know that disclaimer the investment folks always use - "Past
performance is not a guarantee of future results"? It seems to me that
the same holds true for a GFCI.

I submit that we should not feel confident that a GFCI will protect us
just because it passed the test. In reality, all we can do is look back
and say whether or not it would have protected us since the last test.

Sleep well!

Testing GFCI's - A Philosophical Discussion
 

how about testing circuit breakers by applying too high a current?

Testing GFCI's - A Philosophical Discussion
 

"DerbyDad03" wrote in message
oups.com...
I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. A GFCI is an electromechanical
device and the possibility exists that the test we just performed was
the last time that particular unit was going to work.

Basic statistics require point 3:

3 - A GFCI that is 10 years old and never been tested is less likely to trip
on a fault current. Why? Because, if it had failed to test over the 10
year period, presumably it would no longer be in the statistical pool.

Testing GFCI's - A Philosophical Discussion
 

What, specifically, are asking us to look at?

buffalobill wrote:
http://www.codecheck.com/codecheck_r...ctr.html#shock

DerbyDad03 wrote:
I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. A GFCI is an electromechanical
device and the possibility exists that the test we just performed was
the last time that particular unit was going to work.

Granted, if it fails the test, we know we should replace it, so we're
really checking for a failed device, not a working device. Perhaps we
should feel better (read: relieved) when the test fails, because we
have the opportunity to replace the failed device. Ah, but wait - once
we replace the device and test it, all we really know is that it passed
it's initial test - we still don't know that it will work when it is
needed.

You know that disclaimer the investment folks always use - "Past
performance is not a guarantee of future results"? It seems to me that
the same holds true for a GFCI.

I submit that we should not feel confident that a GFCI will protect us
just because it passed the test. In reality, all we can do is look back
and say whether or not it would have protected us since the last test.

Sleep well!

Testing GFCI's - A Philosophical Discussion
 

how about testing circuit breakers by applying too high a current?

I did that after I bought my house

Testing GFCI's - A Philosophical Discussion
 

DerbyDad03 wrote:
Instead of replying on list, Chris cluttered my inbox with, amongst
other ramblings,

Sorry about that...I had intended for that to go to the list and was
actually wondering why I hadn't seen it.

"Heck, if you're going to worry about stuff, why not worry about the
airbags in your car--you have no way to test those until they're
actually needed..."

I don't recall posting that I was "worrying" about anything. I simply
made some points to start a fun discussion and it appears that I
accomplished my goal.

I would submit that if one is not confident about something, then you
have some doubts as to its effectiveness. Add to that the sarcastic
"sleep well", implying that we shouldn't, and I don't think my comment
was too far off.

Chris

Testing GFCI's - A Philosophical Discussion
 

Chris Friesen postulated:
- I would submit that if one is not confident about something, then you
have some doubts as
- to its effectiveness.

Doubting something's effectiveness is not the same thing as worrying
about it. I doubt that many of the health aids they sell on late night
TV are effective, but I sure don't worry about them.

- Add to that the sarcastic "sleep well", implying that we shouldn't,
and I don't think my comment
- was too far off.

What keeps other's up at night may not be the same thing that keeps me
up at night. Perhaps I was just trying to instill a little worry in
others. g



Chris Friesen wrote:
DerbyDad03 wrote:
Instead of replying on list, Chris cluttered my inbox with, amongst
other ramblings,

Sorry about that...I had intended for that to go to the list and was
actually wondering why I hadn't seen it.

"Heck, if you're going to worry about stuff, why not worry about the
airbags in your car--you have no way to test those until they're
actually needed..."

I don't recall posting that I was "worrying" about anything. I simply
made some points to start a fun discussion and it appears that I
accomplished my goal.

I would submit that if one is not confident about something, then you
have some doubts as to its effectiveness. Add to that the sarcastic
"sleep well", implying that we shouldn't, and I don't think my comment
was too far off.

Chris

Testing GFCI's - A Philosophical Discussion
 

You test a GFI without a load so no arcing occurs on the contact unlike a
circuit breaker that requires testing a greater than full load. Out of
curiosity has anyone had a GFI that didn't trip on push to test or with an
external short to ground?


"Charles Schuler" wrote in message
. ..

"DerbyDad03" wrote in message
oups.com...
I was pondering the concept of "monthly testing" of GFCI's the other
day, basically trying to determine if it had any merit. Here are my
thoughts...

What does a passing testing of a GFCI tell us? It tells us 2 things:

1 - That the testing circuitry worked at the time of the test; and
2 - Had there been a fault in the last month, there's a high
probability that it would have tripped.

What it doesn't tell us, in any certain terms, that the device will
work the *next* time there is a fault. A GFCI is an electromechanical
device and the possibility exists that the test we just performed was
the last time that particular unit was going to work.

Basic statistics require point 3:

3 - A GFCI that is 10 years old and never been tested is less likely to
trip on a fault current. Why? Because, if it had failed to test over the
10 year period, presumably it would no longer be in the statistical pool.