circuit breaker as switch

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buck33k

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Washington state and North Carolina
An air compressor is turned on daily using a 2 pole 40 amp circuit breaker. HACR

5 HP 230 v.
Nameplate FLA 22.8
table value FLA 28
circuit conductors #8

Is there a safety issue with the existing breaker as far as the initial current imposed on the breaker? Is there another breaker style or rating which would be a better choice?
 
Most circuit breakers today have a mark that reads SWD meaning that it is suitable to be used as a switch. If this is an older breaker that could be a problem.
 
Thanks Dennis. I believe only 15 or 20 amp breakers could be SWD but I may be wrong.

My concern is with the requirements of 430.109. I know what I have described is probably done occasionally but may be prohibited or unsafe.

edited to add: The breaker is a modern Seimans.
 
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I'm preaty sure they can be used to control the utilization equipment.
http://www.mikeholt.com/mojonewsarchive/NEC-HTML/HTML/ElectricalCircuitBreakers~20020419.htm


Part 1
Circuit Breakers Defined
The American National Standards Institute (ANSI) defines a circuit breaker as: “A mechanical switching device, capable of making, carrying and breaking currents under normal circuit conditions. Also capable of making and carrying for a specified time and breaking currents under specified abnormal circuit conditions, such as those of a short circuit” The NEC defines a circuit breaker as “a device designed to open and close a circuit by non-automatic means, and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within it’s rating.” While the ANSI and the NEC definitions describe the same family of devices, they do have some differences, the same is true with the actual circuit breakers them selves. They are much the same in general terms; however there are a number of significant differences between the many types of electrical circuit breakers installed in many types of facilities today.

Circuit Breakers As Switches
Both the ANSI and the NEC definitions acknowledge the potential for the legitimate use of circuit breakers as switches. Switches (pass, but do not consume electrical power) are considered as being control devices, thus one may also say that a breaker is a control device, or a controller. .....
Click to expand...
 
MD
Thanks for link to the good article. There was a statement in there in reference to circuit breakers:

While circuit breakers can be legitimately and safely used as switches, the frequency and duration of such use is very limited. Routinely circuit breakers are manually operated for service-maintenance, and repair type activities. With the preceding enhancing our understanding; we can say that circuit breakers can legitimately be used as switches, generally they are not intended for prolonged frequent or repetitive manual breaking and making type control of electrical energy utilization equipment.

I wonder if my original scenario would be considered repetitive manual breaking and making?
 
buck33k said:
MD
Thanks for link to the good article. There was a statement in there in reference to circuit breakers:

While circuit breakers can be legitimately and safely used as switches, the frequency and duration of such use is very limited. Routinely circuit breakers are manually operated for service-maintenance, and repair type activities. With the preceding enhancing our understanding; we can say that circuit breakers can legitimately be used as switches, generally they are not intended for prolonged frequent or repetitive manual breaking and making type control of electrical energy utilization equipment.
Click to expand...

I wonder if my original scenario would be considered repetitive manual breaking and making?
Click to expand...

Yeah I saw that and I would say that is why they make bad controllers not sure there is a violation though:confused:
 
Here is a link to an older Westinghouse document that is still relevent today when it comes to breaker life.
I believe the UL test that are required that are shown on page 3 should impress most people.
Play close attention to the endurance tests at FL and NL.

http://www.eaton.com/ecm/idcplg?Idc...sed&Rendition=Primary&&dDocName=1016115402294

When it comes to switch duty I know that Westinghouse did not do anything to the mechanical part of the breaker but in the contacts.
You may note the HID and SWD breakers are directed to the small breakers such as the plug on breakers. They have a lot to deal with when it comes to the ballasts that they turn on and of.
When these small breakers are designed Westinghouse broke them up into families such as 15-30at, above 30-70at, above 70-100at where each had a different set of contacts.
To simply meet the SWD requirements all families use the same set of contacts as those in the 100a family.
There really isn?t any magic or foo-foo dust but it's the contacts that must last equal to or greater than the load FL and NL mechanical tests.
 
buck33k said:
I wonder if my original scenario would be considered repetitive manual breaking and making?
Click to expand...

No, repetitive would be defined as number of operations per minute and per hour. For example the pressure switch cycles repetitively.

Small molded case breakers primarily care about the amount of current they need to break not the amount of current they make, as long as the make current is lower than about 6x FLA.
 
jim dungar said:
No, repetitive would be defined as number of operations per minute and per hour. For example the pressure switch cycles repetitively.

Small molded case breakers primarily care about the amount of current they need to break not the amount of current they make, as long as the make current is lower than about 6x FLA.
Click to expand...

Jim help me with that one. I do not question you just educate me a bit more.
 
While, all standard plug-in circuit breakers are molded case, not all molded case are plug-in. The two primary classes of 600V circuit breakers are "molded case" and "power".

UL only has SWD ratings for 15A and 20A single pole breakers. These breakers have passed the same tests as standard 1P light switches in regards to switching tungsten and fluorescent lamps.

UL HID ratings are available for greater ampacities (60A max?) and multi-pole. HID breaker contacts are designed to handle the higher make current (often over 10x FLA) of ballasted luminaries.
 
jim dungar said:
While, all standard plug-in circuit breakers are molded case, not all molded case are plug-in. The two primary classes of 600V circuit breakers are "molded case" and "power".

UL only has SWD ratings for 15A and 20A single pole breakers. These breakers have passed the same tests as standard 1P light switches in regards to switching tungsten and fluorescent lamps.

UL HID ratings are available for greater ampacities (60A max?) and multi-pole. HID breaker contacts are designed to handle the higher make current (often over 10x FLA) of ballasted luminaries.
Click to expand...

Thanks for the good explanation.
 
Dennis Alwon said:
Most circuit breakers today have a mark that reads SWD meaning that it is suitable to be used as a switch. If this is an older breaker that could be a problem.
Click to expand...
Dennis: NEC required HID rated CBs in the 2002 NEC, a HID CB can be used for SWD so most mfgs no longer offer a SWD rated CB.
 
Tom.,,

I hate to " challange" you on this part but can you point where they did rewrite that related with the SWD breaker [ i know it became standard feateure on most SP breakers]

I know i did see it mention on 02 and 05 but not sure if that carry over on 08 [ i did not get chance to read all of it yet so it will be little while before i hit that area ]


Thanks

Marc
 
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