Why did the breaker trip after a power outage?

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On 5/8/2012 6:09 PM, Metspitzer wrote: ...

AFAIK (and the Cutler-Hammer brochure I downloaded from the above link indicates also) that this UL reqm't only applies to fluorescent lighting loadings???
For commercial buildings like retail or office space, I'm sure they are. I've never bothered to check whether the breakers at the church are rated or not; the frequency of times they get switched is so low and the loadings are limited that I've never worried about it.
This panel was installed in the mid-60s in a wiring upgrade to the original (1920s) building in conjunction w/ an expansion project. AFAIK there's never been a breaker failure in the 50 years since.
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That speaks for itself.
I have never bought a swd breaker either, but I would have expected them to last longer if you are using them as switches.
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On 5/8/2012 9:58 PM, Metspitzer wrote: ...

I strongly suspect that is mostly related to how heavy the switching cycle is as well as the switching load. There's two effects; the mechanical mechanism and the possible arc/pitting of the actual contacts afaict. Higher amps are obviously worse for the one; the mechanics of the switch itself are the other and one presumes probably there's some difference there in one intended for specific use as switch as compared to "just" a breaker.
But, my sense is that for small loads and reasonable use the likelihood is that the normal user wouldn't ever notice any difference at all.
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On 5/8/2012 6:22 PM, dpb wrote:

From the UL White book: "Circuit breakers marked "SWD" and rated 347 V or less are suitable for switching fluorescent lighting loads on a regular basis at their rated voltage.
"Circuit breakers marked "HID" have been investigated for switching high-intensity discharge lighting loads on a regular basis at their rated voltage.
"Circuit breakers rated 50 A or less and 125/250 V or less are investigated for use with tungsten-filament lamp loads.
"Circuit breakers are tested under overload conditions at six times the rating to cover motor circuit applications and are suitable for use as motor circuit disconnects per Section 430.109 of the NEC.
"Circuit breakers investigated for use with heating, air conditioning and refrigeration equipment comprising multi-motor or combination loads are marked "HACR TYPE," in conjunction with the Listing Mark. Such circuit breakers are suitable for use with heating, air conditioning and refrigerating equipment marked for use with HACR type circuit breakers." end quote
Both incandescent lamps and motors have an inrush/start current of about 6x normal current. Breakers are intended to not trip powering on incandescents.
Contacts can be damaged by arcing when the breaker is opened repeatedly. The old fluorescent ballasts were inductive and caused arcing - hence SWD rating. (I don't think the electronic ballasts arc much on opening.) My guess is HID ballasts are even more inductive and arc more on opening. I don't remember ever seeing a "HID" rating.
I have no idea how "HACR" breakers are different.
A garden variety 20A SquareD breaker I looked at is marked "SWD" and "HACR".
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I guess it all came on the same time after failure. That might rule out that possibility. I have turned certain transformers on, and depending on what part of the ac cycle, blew fuses. Some things are going to draw more current at lower initial turn on too.
Greg
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wrote:

I know that CRT computer monitors and crt tv sets always draw a lot of power upon starting. When I had them, I could see a surge on the room lights, particularly when a dimmer was installed.
One of the games still is a CRT type. I was there tonite again, and talked to the owner about it. I also noticed that I mis-counted. There are actually 6 games, a jukebox, 3 signs a clock, and an ATM machine all on that circuit. I also found out that the day they opened the bar some years ago, they had a power failure. An electrician came and found almost every outlet, except the ones behind the bar on the same circuit. He split it into 4 breakers. One for each wall. But he said that back then they only had 2 or 3 video games and a jukebox in the whole place. The company the furnishes the games keeps bringing in more and more stuff. He said the revenue from these games is small, but it all helps pay the bills. But he also said the electric bill is much higher than it used to be. Kind of makes me wonder if it's worth having all those games.... I seldom see them being used.....
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snipped-for-privacy@toyotamail.com wrote:

Look up "inrush current".
--
I saw a human pyramid once. It was very unnecessary. -Mitch Hedberg


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On Sunday, May 6, 2012 4:01:49 PM UTC-5, (unknown) wrote:

This is usually the case for storms...being outdoors! *L*
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You never had one of these?
http://static7.depositphotos.com/1011028/677/v/950/depositphotos_6775386-Magic-Snow-Dome.jpg
http://www.promo-wholesale.com/Upfiles/Prod_n/Import-Acrylic-Snow-Dome_20090827546.jpg
Being Mormon, and reader of Gary Larson's far side. I'd sure like a Donner Party snow dome, some time. Appeals to my sick and twisted side.
Christopher A. Young Learn more about Jesus www.lds.org .
On Sunday, May 6, 2012 4:01:49 PM UTC-5, (unknown) wrote:

This is usually the case for storms...being outdoors! *L*
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On Sunday, May 6, 2012 5:01:49 PM UTC-4, (unknown) wrote:

maybe just replace the breaker. breaker age/fatigue could have it tripping at say 12 amps instead of 15. use a "kill a watt" meter at any outlet. electricians use a clamp on ammeter at the panel. test each device to match their wattage plates. you can call the power company on a slow day to check their power lines to the building meter for any damage. you can request a replacement power meter from the company.
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snipped-for-privacy@toyotamail.com wrote:

Breakers are designed to trip while passing power. I'd be amazed if the breaker tripped DURING the power outage.
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On Sunday, May 6, 2012 5:01:49 PM UTC-4, (unknown) wrote:

Back in the late 70s I worked in a game arcade. I opened the business about 4 PM and closed it around 11 PM . The owner had told me to shut down each machine individually and dont use the breaker. I didn't listen to him and started just shutting off the breakers(2 of them) and this worked for a while then one breaker would pop once in a while but come back up if I reset it. I figure still no big deal and kept on doing it until a couple of weeks later it didn't reset and had to be replaced. Owner was not happy with me.
Also would just about be willing to bet money the breaker is 15A. The circuit was probably never intended to have something plugged into every outlet and have them all come on at once.
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On Sun, 06 May 2012 16:01:49 -0500, snipped-for-privacy@toyotamail.com wrote:

Why did the power go out in the first place??
Lightning strike perhaps? I.E. Voltage/current surge probably tripped the Power CO's overload circuits..
The same surge could have tripped the breaker in question. Most video games have power supplies protected by surge suppressor and RF-filters. MOV's protect by shorting out the excess energy.
Thus the transient voltage spike resulted in large current surge which could have tripped the breaker either when power was just about to totally fail, or when it was abruptly restored.
Note: When significant HV circuits are interrupted or re-connected, it's not exactly an instantously process (slow, hundreds of milliseconds), and there is significant arcing involved. Arcing =major source of high frequency voltage spikes.
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