bensonelectric
Senior Member
How many times can a breaker be turned off before it is worn out?
Breakers as switches
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charlie
Senior Member
- Location
- Indianapolis
Re: Breakers as switches
Matt, circuit breakers are tested as switches and some are rated for a specific type of load such as SWD and HID for fluorescent or high intensity discharge lighting. So, to answer your question, there is no answer just as there is no answer as to the number of time a snap switch in your bedroom may be operated before it is worn out.
Matt, circuit breakers are tested as switches and some are rated for a specific type of load such as SWD and HID for fluorescent or high intensity discharge lighting. So, to answer your question, there is no answer just as there is no answer as to the number of time a snap switch in your bedroom may be operated before it is worn out.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: Breakers as switches
Breaker mechanical life depends on the size of the breaker.
As Charlie said, a 15A 1P breaker marked SWD or HID has passed the same performance and life tests as a normal wall switch. But a 3000A 3P breaker may only have a mechanical life of 50 operations. I believe this information can be found in the NEMA AB1 publication on circuit breakers
Breaker mechanical life depends on the size of the breaker.
As Charlie said, a 15A 1P breaker marked SWD or HID has passed the same performance and life tests as a normal wall switch. But a 3000A 3P breaker may only have a mechanical life of 50 operations. I believe this information can be found in the NEMA AB1 publication on circuit breakers
electricmanscott
Senior Member
- Location
- Boston, MA
Re: Breakers as switches
Going to the basement, be right back.
Going to the basement, be right back.
physis
Senior Member
Re: Breakers as switches
When I used to design stuff the manufacturer data would include tested number of operations for switches. I think in the millions was typical for some switches. Those certainly weren't circuit breakers though. I would expect the manufacturer knows and a distributor might be able to look it up.
I wonder about circuit breakers too. Some of them feel like there's too much going on in there to survive a lot of switching on and off.
Charlie already said it but there's 240.83(D) and 404.11
When I used to design stuff the manufacturer data would include tested number of operations for switches. I think in the millions was typical for some switches. Those certainly weren't circuit breakers though. I would expect the manufacturer knows and a distributor might be able to look it up.
I wonder about circuit breakers too. Some of them feel like there's too much going on in there to survive a lot of switching on and off.
Charlie already said it but there's 240.83(D) and 404.11
- Location
- Massachusetts
Re: Breakers as switches
This all reminds me of a time I was sent to a large movie theater to help out with some inspections by the Fire Dept. and the electrical inspector.
They wanted to check out the emergency lighting and fire alarm system.
The fire chief had me flipping a 1,200 to 1,600 amp main GFP breaker on and off like a light switch. :roll:
This model was one a with a spring that you pump up tension on with a lever than push a button to snap the breaker closed.
I bet I closed that switch 15 times each time waiting for the breaker to self destruct.
This all reminds me of a time I was sent to a large movie theater to help out with some inspections by the Fire Dept. and the electrical inspector.
They wanted to check out the emergency lighting and fire alarm system.
The fire chief had me flipping a 1,200 to 1,600 amp main GFP breaker on and off like a light switch. :roll:
This model was one a with a spring that you pump up tension on with a lever than push a button to snap the breaker closed.
I bet I closed that switch 15 times each time waiting for the breaker to self destruct.
petersonra
Senior Member
- Location
- Northern illinois
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- engineer
Re: Breakers as switches
I once saw a medium voltage MCC where a breaker being used as a motor starter had exploded. no one ever figured out quite why, but there was black marks in the space where it used to be in the MCC.
Very impressive.
I once saw a medium voltage MCC where a breaker being used as a motor starter had exploded. no one ever figured out quite why, but there was black marks in the space where it used to be in the MCC.
Very impressive.
- Location
- Massachusetts
Re: Breakers as switches
That's what happens after the management drags their feet on repairs to the emergency lighting.
Most of the cinemas did not have functioning emergency lighting.
Short answer, he was looking to make the testing take as long as possible keeping the building closed for business.Originally posted by physis:
I don't even want to know what the fire guy was looking for
That's what happens after the management drags their feet on repairs to the emergency lighting.
Most of the cinemas did not have functioning emergency lighting.
electricmanscott
Senior Member
- Location
- Boston, MA
Re: Breakers as switches
How can you expect them to be able to afford things like emergency lighting. Have you seen what it costs to go to the movies and have some snacks while you are there? No way can they be making any money.
How can you expect them to be able to afford things like emergency lighting. Have you seen what it costs to go to the movies and have some snacks while you are there? No way can they be making any money.
- Location
- Massachusetts
Re: Breakers as switches
Yeah Scott I was almost in tears with sympathy.
I did get 1/2 dozen free passes from the manager though.
Yeah Scott I was almost in tears with sympathy.
I did get 1/2 dozen free passes from the manager though.
Re: Breakers as switches
Even to achieve the initial standard UL489 listing the breaker must pass a sequence of tests which includes in part a number of different test from a 200% and 135% calibration checks, various overload test at 600% rated current, temperature rise checks at 100% load, endurance test (as you are inquiring about), the short circuit, dielectric, and calibration checks.
The reason I referred to all these other tests is that endurance tests are not just simply conducted until the breaker fails but are conducted at FL, and NL at a given number of operations a minute. So your question of
Breakers 0-100 rating must be able to be operated 6000 FL and 4000 NL @6 operations per minute. ratings of 101-225 are 4000 FL and 4000 NL @ 5/min. 226-600a, 1000 FL and 5000 NL @4/min, etc, after which they must pass the calibration tests again.
They also must pass a specific short circit 7 or 8 times and after that pass the 200% calibration test again.Then after all of that stuff the breaker must then pass a dielectric withstand test for one minute.
When it comes down to it breakers that are used as switches can be considered as being exercised which keeps the lubrication circulated around the moving parts as well as the wiping action that takes place then a breaker is opened and closed.
Even to achieve the initial standard UL489 listing the breaker must pass a sequence of tests which includes in part a number of different test from a 200% and 135% calibration checks, various overload test at 600% rated current, temperature rise checks at 100% load, endurance test (as you are inquiring about), the short circuit, dielectric, and calibration checks.
The reason I referred to all these other tests is that endurance tests are not just simply conducted until the breaker fails but are conducted at FL, and NL at a given number of operations a minute. So your question of
means that the breaker must not only pass a given number of mechanical operations but must also pass electrical performance test which should make you very secure in applying breakers in switching applications.
Breakers 0-100 rating must be able to be operated 6000 FL and 4000 NL @6 operations per minute. ratings of 101-225 are 4000 FL and 4000 NL @ 5/min. 226-600a, 1000 FL and 5000 NL @4/min, etc, after which they must pass the calibration tests again.
They also must pass a specific short circit 7 or 8 times and after that pass the 200% calibration test again.Then after all of that stuff the breaker must then pass a dielectric withstand test for one minute.
When it comes down to it breakers that are used as switches can be considered as being exercised which keeps the lubrication circulated around the moving parts as well as the wiping action that takes place then a breaker is opened and closed.
physis
Senior Member
Re: Breakers as switches
Bob, you would probably know about this, or a lot of you guys for that matter.
What is so special about HID as a load that there's a need for identification in 240.83(D)?
Edit: Free passes, the get in price is fair, it's that nasty food they sell that's puts you back a notch.
[ January 16, 2005, 04:08 PM: Message edited by: physis ]
Bob, you would probably know about this, or a lot of you guys for that matter.
What is so special about HID as a load that there's a need for identification in 240.83(D)?
Edit: Free passes, the get in price is fair, it's that nasty food they sell that's puts you back a notch.
[ January 16, 2005, 04:08 PM: Message edited by: physis ]
- Location
- Massachusetts
Re: Breakers as switches
Nope, I do not, but I bet templdl probably knows.
Re: Breakers as switches
HID breakers were, for a while, a self certified manufacturer rating which I understand UL has finally zeroed in on a short time back and has a standard for. Mercury vapor, metal halide, and HP sodium light loads ballasts that provide a high open circuit voltage for starting present an additional challenge for a breaker in that they have to withstand the high voltage and current spikes associated with these systems. From what I understand a common problem to be is that it is posible to tease the contacts by causing them to float very slightly then arc melting the contact surfaces. Because the breaker is still trying to hold the contacts closed the contacts may end up stuck together.
Also, remember that switching duty breakers, which are marked "SWD," have been a UL listed device for quite some time now for flourescent loads.
Anyway, both HID and SWD rated breakers are essentially common breakers that have additional testing done to allow them to be used in these applications. I can't recall if there has been any magic done with the design of these devices other than assuring that they will operate in those applications through UL testing standards.
I hope that makes sense.
Dave
HID breakers were, for a while, a self certified manufacturer rating which I understand UL has finally zeroed in on a short time back and has a standard for. Mercury vapor, metal halide, and HP sodium light loads ballasts that provide a high open circuit voltage for starting present an additional challenge for a breaker in that they have to withstand the high voltage and current spikes associated with these systems. From what I understand a common problem to be is that it is posible to tease the contacts by causing them to float very slightly then arc melting the contact surfaces. Because the breaker is still trying to hold the contacts closed the contacts may end up stuck together.
Also, remember that switching duty breakers, which are marked "SWD," have been a UL listed device for quite some time now for flourescent loads.
Anyway, both HID and SWD rated breakers are essentially common breakers that have additional testing done to allow them to be used in these applications. I can't recall if there has been any magic done with the design of these devices other than assuring that they will operate in those applications through UL testing standards.
I hope that makes sense.
Dave
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: Breakers as switches
Some manufacturers may adjust the magnetic trip of their standard breaker in order the get an HID rating. The inrush current of HID ballasts is usually 10-14 times FLA versus a motor of only 6-10 times.
Some manufacturers may adjust the magnetic trip of their standard breaker in order the get an HID rating. The inrush current of HID ballasts is usually 10-14 times FLA versus a motor of only 6-10 times.
Re: Breakers as switches
physis and jim may both have a point. Breakers has been commonly calibrated to 10x there rating with a calibration range of anywhere from +-20 and even more. NEMA AB4 tests state that the breaker should test within +-25% of the manufacturer's published trip rate.
The 10x is common with larger frame breakers but becomes a somewhat gray area with the smaller residential breakers that are produced like popcorn. It has been my experience that the manufacturer that I am most familiar with broke their resi. breakers of 15-100a into three groups, 15-30a, to 70a, and 100. You may have notic4es this when you look at trip curves for thes products. All the breakers within a given group were made of the same parts and had the same magnetic calibration. The only difference was their thermal elements.
Thus, simply taking a breaker in the 100a group and giving it a 20a thermal element would provide bigger contacts and a higher magnetic calibration without it being necessary to redesign the breaker to pass a SWD/HID UL test.
It is also interesting to note that some manufactures residential breaker have a standard 6-7x magnetic trip pickup and define and optional breaker that is calibrated 10X+ as high mag. Then other manufactures manufacture breakers with a standard 10x+ and then had an optional low mag. available.
Dave
physis and jim may both have a point. Breakers has been commonly calibrated to 10x there rating with a calibration range of anywhere from +-20 and even more. NEMA AB4 tests state that the breaker should test within +-25% of the manufacturer's published trip rate.
The 10x is common with larger frame breakers but becomes a somewhat gray area with the smaller residential breakers that are produced like popcorn. It has been my experience that the manufacturer that I am most familiar with broke their resi. breakers of 15-100a into three groups, 15-30a, to 70a, and 100. You may have notic4es this when you look at trip curves for thes products. All the breakers within a given group were made of the same parts and had the same magnetic calibration. The only difference was their thermal elements.
Thus, simply taking a breaker in the 100a group and giving it a 20a thermal element would provide bigger contacts and a higher magnetic calibration without it being necessary to redesign the breaker to pass a SWD/HID UL test.
It is also interesting to note that some manufactures residential breaker have a standard 6-7x magnetic trip pickup and define and optional breaker that is calibrated 10X+ as high mag. Then other manufactures manufacture breakers with a standard 10x+ and then had an optional low mag. available.
Dave
Re: Breakers as switches
I manage a gas station and am aware of an issue surrounding the use of our HID lighting system (about 20 of them) using a circuit breaker as a switch.
Our company has an issue with safety and I feel its paramount that this get resolved.
Is there anything under AB1 that requires a switched system (photo eletric, timer, relay) be employed where a safety device is the only switched component?
I manage a gas station and am aware of an issue surrounding the use of our HID lighting system (about 20 of them) using a circuit breaker as a switch.
Our company has an issue with safety and I feel its paramount that this get resolved.
Is there anything under AB1 that requires a switched system (photo eletric, timer, relay) be employed where a safety device is the only switched component?
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