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Posted By: Jennybean Resetting a Breaker - 10/05/02 04:27 PM
In our kitchen at work, the dishwasher tripped the breaker and the electrician told me just to reset the breaker. My husband says you need to know what tripped it before resetting, because someone might get injured. Who's right? Your help would be appreciated! Thanks!
Posted By: sparky Re: Resetting a Breaker - 10/06/02 01:25 AM
basically, a breaker will 'trip' from overcurrent (drawing more umph that usual) or a ground fault ( hot wire meets ground)
Posted By: jlhmaint Re: Resetting a Breaker - 10/09/02 02:07 AM
Technically yes. You are suppose to find the fault that caused the breaker to trip before resetting it. This is not always the case though. But if you have a plant electrician it is his job not yours to reset the breaker and address the problem. i would tell him to reset it because if something would happen, is he going to back you up and tell management that he told you to reset the breaker? Probably not!!
Posted By: OSHA Professor Re: Resetting a Breaker - 12/08/02 10:12 PM
Jennybean,
Did the electrician tell you not to stand directly in front of the panel when resetting the breaker ?
Don't want to alarm you but we have investigated decapitations as a result of someone closing (resetting) a breaker into a fault condition while standing directly in front of the panel. The panel cover actually blows off the enclosure with a very significant force (15 tons per square meter). This is called an arc blast or arc flash electrical hazard and is quite common. Once you have identified the breaker you want to reset you should always stand off to the side of the panel (not in front of it) when throwing the breaker handle. The same is true for throwing a handle on a disconnect switch.
There are work practices both in OSHA regulations / standards as well as NFPA (National Fire Protection Association) Standards that prohibit the manual resetting of circuit breakers untill "it has been determined that the equipment and circuit can be safely energized".
There are also requirements that you as an unqualified electrical person be trained to recognize and avoid electrical hazards which you are likely to encounter in the course of your work.
There are also training requirements for that electrician (qualified person according to OSHA)also.
Check out OSHA's site at www.osha.gov
to find out more about osha programs and safety and health in the workplace.

[This message has been edited by OSHA Professor (edited 12-08-2002).]
Posted By: sparky Re: Resetting a Breaker - 12/08/02 10:29 PM
OSHA prof's right.

there's been many a thread about being careful about tripped breakers here too,

many stories from many electricians here

we should have included a warning i guess.

[Linked Image]
Posted By: ThinkGood Re: Resetting a Breaker - 12/15/02 02:56 AM
Jennybean:

It's nice to read that your husband truly cares about you. He's absolutely correct -- especially because it's in the workplace, where you may have no idea if somebody was "repairing" something and caused a problem with the circuit, etc.

OSHA Professor and Sparky:

Relative to the arc flash hazard, the breakers in my home (Square-D HOM type) have 3 positions for the toggle switch. If something causes a fault, the breaker "trips" but the toggle is halfway between "ON" and "OFF." The "ON" and "OFF" positions are just what their names imply. Thus it is easier to tell if something was shorted/overdrawn, etc. if various breakers are on and off at the same time.

That said...I just would like a clarification...are you saying that the threat of the arc flash is present only when there is something on the circuit that still needs to be repaired, (that would be the fault, for example, a short circuit, correct?) or is this threat always there?

I think a nice length of dowel stick might be worth it ;-)
Posted By: OSHA Professor Re: Resetting a Breaker - 12/15/02 11:41 PM
ThinkGood,

I am not thoroughly familiar with that particular model of breaker, however all the breakers I am familiar with will trip with the “handle” resting in the middle position. This trip or “opening” (electrical tech talk) of the breaker could have been caused by an overload, as in plugging in too much stuff(load) or alternatively, a fault condition (short circuit in some stuff plugged into the branch circuit). The fault or short circuit condition could also have occurred in the branch circuit wiring itself rather than utilization equipment (some stuff) plugged into the branch circuit. There is no way of knowing by looking at the tripped breaker. If the breaker is closed (reset) into a fault there is a possibility of an arc flash. Still best to stand off to the side of the panel and turn / look away when resetting a breaker. Also a good safe work practice would be not to wear synthetic or synthetic blend clothing such as, poly blend shirts, nylon windbreaker jackets etc. when doing this operation. Wanna be extra safe also wear heavy cotton or leather gloves. It’s not really overkill it kind of like wearing the right clothing if you are welding underneath your car, or sandblasting, safety glasses ehen using a chain saw etc, etc, or anything which requires the right clothing AKA, PPE personal protective equipment).
When it comes to the wearing of PPE, remember. You can't win, you can only loose or break even! You go to work with two eyes, two hands, two legs, ten digits etc. You won't ever return home with more only the same or --if you loose, you'll return home with less.

OSHA Professor
Posted By: ThinkGood Re: Resetting a Breaker - 12/16/02 02:37 AM
[Linked Image from 65.108.216.53]
Posted By: james27613 Re: Resetting a Breaker - 12/18/02 03:07 AM
Time well spent, I learned something new today !

And my wife thinks I just look at ebay.
Posted By: :andy: Re: Resetting a Breaker - 10/23/03 05:46 PM
regarding the ARC BLAST

what exactly is this? Here, When you switch a breaker of 16 or 25A into total short circuit, you will hear a POFF in the inside and the handle will be loose, because the inner mechanics slipped through. you will need to return the handle to Off position to re-pickup the mechanics inside.

why should this cause the panel to be blown off with 15 tons/meter??

i've never heard of anything like this??

[This message has been edited by :andy: (edited 10-23-2003).]
Posted By: swedejr Re: Resetting a Breaker - 01/06/04 10:11 PM
I always use the "Left-hand Rule"- Stand to the right side of the disconnect (or breaker) and use your left hand to throw the switch. Keeps your body "out of the line of fire"
Posted By: PCBelarge Re: Resetting a Breaker - 01/26/04 01:01 AM
Andy
The incident that tripped the breaker could have caused damage to the lineside conductors that feed the panel, or any other conductor(s) in the panel. When reenergizing the said breaker, it may cause this situation to escalate into a catastrophic situation, which is a fault condition that can lead to an arcblast condition. The arcblast can develop very quickly into multiphase arcblast that has tremendous potential to cause property and bodily harm.
Try a www.google.com search on this subject, and you will find plenty of info on it. www.bussmann.com also has very good information on this subject.

Pierre
Posted By: cpalm1 Re: Resetting a Breaker - 02/10/04 04:09 AM
I personally have never heard of low amperage (household light and outlet breakers causing arc flash.
however when resetting a large amperage (industrial) breaker into a dead short a big arc results. the breaker could weld shut untill a meltdown occurs, but normally it will just pop open again. when it pops, there is a giant arc. in arc flash, the arc ionizes the air and makes it conductive. even though the breaker is open, the ionized air is arcing and carrying current accross the opened points of the breaker. this arcing makes even more ionized air. eventually the ionized air fills the breaker panel. arc flash then starts to occur accross the bus bars in the panel. the air is heated so quickly that the only way for it to escape the panel is to blow the front off. I have also heard that the massive amount of heat and the arcing will even dissosiate (split) the hydrogen and oxygen from moisture in the air and any condensation in the panel. if that is true, your panel basically turns into a hydrogen bomb
Posted By: :andy: Re: Resetting a Breaker - 02/28/04 07:46 PM
The standard for industrial power breakers with several hundred amperes is, that they hve to be able to safely shut off even in case of a total short circuit. So exactly what you mentioned, at the given voltage the breaker will not meltdown. to kill the arc, these breakers (also the samll household ones) have "loeschkammern" (i dont know the word), small metal plates in a row to weaken the arcs power and finally extinguish it.

If the poco's transformer short circuit power is bigger that the short switching capacity of your breaker, you have to install another breaker or (mostly here) big melting fuses with enough switchoff capacity.

with these precautions, and assuming the power transformer works correctly, you wont run into a meltdown nowhere.

just different if you've got an overvoltage on the line due to a transformer coil failure ect.
thats why most (all?) high amperage panels are equipped with surge detectors, also capable of at least the switchoff capacity
of the fuse they are connected to.
they short the line out in case of overvoltage, causing the fuse to blow. These are one-time surpressors, after one strike they're dead.

i've seen boxes for them with a clear front that spring mounted. The tripping detectors would break the cover if it wouldnt lift up [Linked Image]


to come back to the breaker at home: i've never heard f dangers in resetting a shorted breaker. never heard of anyone that heard of anyone who dreamed of someone that heard of this.
the standard after a breaker tripped here is to assure no one is in danger and switch it back on. if it bangs and the breaker tripped again, go for a search.

[This message has been edited by :andy: (edited 02-28-2004).]
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