Using A Circuit Breaker As A Manual Switch

[Bret Cahill]

How many times can you flip a 30 Amp CB on and off before it wears
out? Say you as gentle as possible with the switch.


Bret Cahill

 

[Tom Biasi]

How many times can you flip a 30 Amp CB on and off before it wears
out? Say you as gentle as possible with the switch.


Bret Cahill

Different manufactures have different specs. What do you mean by
"gentle"? Will you whisper sweet things to it while you switch a 30 Amp
load on and off?

Tom

 

[[email protected]]

Some are designed to be used as light switches in retail stores &
factories, but others had warnings not to use them as a switch.

I believe it's called an "switch" or 'S' rating. AFAIK, no
residential breakers have a switch rating.

 

[Bret Cahill]

How many times can you flip a 30 Amp CB on and off before it wears out?

There is no "gentle" for a normal circuit breaker: the toggle action is
so strong that the contacts are going to thump hard no matter what.

What Mr. Terrell said about switch-rated breakers: there was a breaker
box at my dad's shop that had the circuit breakers turned on and off
every working day for the ten years that I worked there, and we never had
a problem (and I would know -- it would have been my job to swap the
breaker out).

How would you know w/o a test, i.e., a short with a known resistance?
Maybe nothing ever went wrong in your shop and the CBs still worked
great as manual switches but had, over the years, been altered as far
as the amperage that shut them off?

A shop would be the last place to offer as evidence as the "do
everything within specs" mentality prevails. Much more compelling
would be the dtisy residential situation test.

The thermal CBs that Square D introduced in 1935 took awhile to for
the bimetalic strip to heat up and pull away from a contact. They
were replaced starting in 1940 with faster acting magnetic CBs.

All the testing and innovation took place at the plant.

But you never hear of electricians advocating anyone going around
testing installed CBs for safety.

This is similar to the idiot light problem. Supposing the idiot light
has burned out?


Bret Cahill

 

[Mr Ron]

But you never hear of electricians advocating anyone going around
testing installed CBs for safety.

This is similar to the idiot light problem. Supposing the idiot light
has burned out?

Here in the UK AFAIK there doesn't seem to be any way to test them. I had a
brocken socket to be replaced and couldn't find the breaker. We tried the
method of shorting the socket to earth to trip it. The wires just fused &
sat there live.
We eventually found the breaker at the other side of the store & had to
replace with a derated one because the resistance of the circuit was too
high.

Ron

 

[mowhoong]

How many times can you flip a 30 Amp CB on and off before it wears

out? Say you as gentle as possible with the switch.





Bret Cahill

Last week my office's 30 years air con switch (single throw 20A ) breakdown, it was Mk brand , I manage to brough one balance stock from a shop at thirty six dollar and it was make in UK during 2009. The seller said you can save cost by using MCB as a switch and it is very commom. BTW a china make unmark rating wall switch only cost one dollar fifty cents only, sure notto use for air con.

 

[Bret Cahill]

But you never hear of electricians advocating anyone going around

Here in the UK AFAIK there doesn't seem to be any way to test them.

What would you need besides an amp meter and some resistors?

I had a
brocken socket to be replaced and couldn't find the breaker. We tried the
method of shorting the socket to earth to trip it. The wires just fused &
sat there live.

That should be proof that the CB was no good.


Bret Cahill

 

[Sjouke Burry]

Here in the UK AFAIK there doesn't seem to be any way to test them. I
had a brocken socket to be replaced and couldn't find the breaker. We
tried the method of shorting the socket to earth to trip it. The wires
just fused & sat there live.
We eventually found the breaker at the other side of the store & had
to
replace with a derated one because the resistance of the circuit was
too high.

Ron

Your wiring needs replacing, a short-circuit should blow even a breaker
of double that spec.
Or you can wait until the house burns down.....

 

[Sjouke Burry]

Last week my office's 30 years air con switch (single throw 20A )
breakdown, it was Mk brand , I manage to brough one balance stock from
a shop at thirty six dollar and it was make in UK during 2009. The
seller said you can save cost by using MCB as a switch and it is
very commom. BTW a china make unmark rating wall switch only cost one
dollar fifty cents only, sure not to use for air con.

Perfect, those China breakers. They make the house burn down very nicely.

 

[Bret Cahill]

But you never hear of electricians advocating anyone going around

Your wiring needs replacing, a short-circuit should blow even a breaker
of double that spec.
Or you can wait until the house burns down.....

An acquaintence owned a nice small old house with a fuse panel,
probably 60 amps for the main. His insurance company refused to
insure it. The house was supposedly torched by a meth head and he
lost everything.


Bret Cahill

 

[Mr Ron]

Your wiring needs replacing, a short-circuit should blow even a breaker
of double that spec.

If you read the above text, we had to derate the circuit from 32A to 16 Amp
as the resistance of the circuit was too great for anything above a 16A
breaker to trip in the required time. Wiring otherwise tested OK.

Or you can wait until the house burns down.....

That's the point, CB was FAULTY & not testable.

Ron

 

[Bret Cahill]

 We eventually found the breaker at the other side of the store & had

If you read the above text, we had to derate the circuit from 32A to 16 Amp
as the resistance of the circuit was too great for anything above a 16A
breaker to trip in the required time. Wiring otherwise tested OK.> Or youcan wait until the house burns down.....

That's the point, CB was FAULTY & not testable.

It seems like it was "over fused" or "over breakered" but how do you
know it was faulty if there was no test to determine if it was faulty?

Apparently you had _some_ test to determine if it was faulty.


Bret Cahill

 

[Bret Cahill]

How many times can you flip a 30 Amp CB on and off before it wears

Thank you both for the insult to my father's abilities to wisely select
appropriate switches, and for once again discouraging me to answer your
questions.

No insult was intended nor should be taken.

Some people do everything on spec and some people occasionally do
things off spec.

And some will try to turn off spec into a religion. The more gnarly
the better. President Obama is not one of those people.

Use switch-rated circuit breakers.

A retired electrician just told me there was no way to damage CBs by
flipping them like switches.


Bret Cahill

 

[Mr Ron]

It seems like it was "over fused" or "over breakered" but how do you
know it was faulty if there was no test to determine if it was faulty?

Apparently you had _some_ test to determine if it was faulty.

They have a rated time/load curve. As the load increases the trip time is
reduced which is why you can load them to the max current rating. The cable
resistance is measured to to give an Earth Fault Current figure that would
trip the CB within 0.4 seconds. If the Live/Earth resistance is too high
for the breaker it won't trip fast enough.

Ron

 

[Cydrome Leader]

An acquaintence owned a nice small old house with a fuse panel,
probably 60 amps for the main. His insurance company refused to
insure it. The house was supposedly torched by a meth head and he
lost everything.

that sucks, but at least he didn't get ripped off by the insurance
company.