Sub-panel w/ main breaker

[ActionDave]

I'm a bit surprised that you would ask. Are you assuming that breakers are now not intended has a manual emergency shut off? Really? If so by what means do you suggest that power be disconnected if there is a need to so in a hurry? Take a pair of linemans pliers and cut the wire? According to the UL489 tests breskers are perfectly capable of the task and come back to do it hundreds of times.
If there were any electrical emergency such that could hurt or kill someone or an arcing fault that is not of a great enough magnetude to trip a breaker or another event that may result in a fire any bright ideas? With all the panels as you say are behind locked doors and all the panel doors are locked, yes, if that is normslly the case then there is an issue. So what you are saying is trying to disconnect a main breaker shouldn't even be considered then.
Wonderful.

Like or not we have made electricity one of the safest forms of energy available and also one of the most important which adds up to the majority of breakers located behind locked doors.

Most every electrical shut off is designed to be part of stopping a mechanical system, shutting of the electricity is a means to an end, not an end to itself. The only thing I can think of off the top of my head where there is a quick way to turn off a main is a shunt trip for the fire department on a commercial building and those are locked up to max, not even the building owner has a key.

 

[iwire]

I'm a bit surprised that you would ask. Are you assuming that breakers are now not intended has a manual emergency shut off?

No the NEC does not intend breakers to be used for that purpose.

If they where for that purpose we could not put them behind locked doors, loeed panel covers, breaker lock on devices etc.

Really?

Yes, really.

If so by what means do you suggest that power be disconnected if there is a need to so in a hurry?

Please describe the incident that causes a need for a human to shut off a breaker 'in a hurry'.

According to the UL489 tests breskers are perfectly capable of the task

Of course they are listed as capable of opening the circuit.

If there were any electrical emergency such that could hurt or kill someone or an arcing fault that is not of a great enough magnetude to trip a breaker or another event that may result in a fire any bright ideas?

So the emergency happens, an untrained person has to figure out which panelboard in the building feeds the branch circuit with a problem, hope it is not behind a locked door, hope the panel cover is not locked etc.




The bottom line is the NEC does not intend breakers to be used as emergency manual shut offs.

 

[Smart $]

...
Please describe the incident that causes a need for a human to shut off a breaker 'in a hurry'.
...

When a person cannot let go while being electrocuted. If you are aware of this occurring and not the person getting electrocuted the best action is to push or pull him away from the power source with a non-conductive means... if feasible. The next best option is to de-energize the circuit (or the best initial action for a third party).

 

[iwire]

When a person cannot let go while being electrocuted. If you are aware of this occurring and not the person getting electrocuted the best action is to push or pull him away from the power source with a non-conductive means... if feasible. The next best option is to de-energize the circuit (or the best initial action for a third party).

Seriously?

Yeah, so in this instance, the person not getting a shock only has to know that the panelboard that happens to be right there, unlocked is the correct panel-board and that it will not shut off things that might inhibit first responders.

If it was you getting a shock and me standing there knowing where it is fed from I bet I still shove you off that item before I even think about finding a breaker.


If an area needs an EPO set up proper ones.

 

[Smart $]

Seriously?

Yes. :happyyes:

Yeah, so in this instance, the person not getting a shock only has to know that the panelboard that happens to be right there, unlocked is the correct panel-board and that it will not shut off things that might inhibit first responders.

If the person does not know which breaker, he should just shut off all the breakers. May be the correct panelboard, may not. The objective is to act quickly with best possible reasoning. May save a life, may not. But not acting at all is the worst approach.

If it was you getting a shock and me standing there knowing where it is fed from I bet I still shove you off that item before I even think about finding a breaker.

And hopefully I would be able to appreciate your action after the fact. :happyyes:

As I said, pushing or pulling is the best course of action if it can be done without subjecting another person to the same level of danger as the one getting electrocuted

If an area needs an EPO set up proper ones.

Agree.

However, an accident cannot be prevented, for the very term means it has already occurred. We can only evaluate the possibility and probability of an accident occurring, and take a course of action to mitigate the occurrence.

 

[goldstar]

All good advice so far. If you plan to use SER cable check the ratings http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet273

If you use a main breaker panel in the remote panel you'll have a 100A main in that remote panel and a 90A breaker (assuming you're using SER cable) in the main panel feeding that remote panel. In theory, the 100A breaker in the remote panel basically becomes a molded case switch. I say "in theory" because I'm assuming if there is a short circuit situation, the 90 A breaker should trip before the 100A, but there's no guarantee IMHO.

 

[goldstar]

FWIW, circuit breakers can be used as on-off switches. See this post from Jerry Peck (scroll down to the bottom of the page) http://www.inspectionnews.net/home_...rcial-inspection/4285-breaker-off-switch.html

I was told by an EI that if a breaker is to be used as an on-off switch it specifically has to be rated for that type of use. Not sure what the designation is.

 

[iwire]

FWIW, circuit breakers can be used as on-off switches.

For sure.

I was told by an EI that if a breaker is to be used as an on-off switch it specifically has to be rated for that type of use. Not sure what the designation is.

240.83(D) Used as Switches. Circuit breakers used as switches in
120-volt and 277-volt fluorescent lighting circuits shall be
listed and shall be marked SWD or HID. Circuit breakers
used as switches in high-intensity discharge lighting circuits
shall be listed and shall be marked as HID

My only point in this thread has been this simple thought.

I think few if any engineers are specifying main breakers in sub panels the purpose of emergency manual power shut offs.


YMMV.

 

[goldstar]

My only point in this thread has been this simple thought.

I think few if any engineers are specifying main breakers in sub panels the purpose of emergency manual power shut offs.
YMMV.

I agree

 

[templdl]

FWIW, circuit breakers can be used as on-off switches. See this post from Jerry Peck (scroll down to the bottom of the page) http://www.inspectionnews.net/home_...rcial-inspection/4285-breaker-off-switch.html

I was told by an EI that if a breaker is to be used as an on-off switch it specifically has to be rated for that type of use. Not sure what the designation is.

Yes, right on, and in addition to there are those who are clueless as to the testing requirements that breakers must pass in before they are blessed with a UL489 listing.
A breaker not being able to be used as a disconnecting means is amusing. And NEC art 230.41 and 42 must be senseless that there must be needs to be able to shut all the power to the building with 6 throws of the hand.e foolish an not required where it needs to be able to shut all the power to the building with 6 throws of the hand.
The point that I was trying to make was to indicate why a main breaker in a subpanel is desirable, though not required, but there are those who think it is a foolish idea which is obvious because of the excuses that they are most likely behind locked doors, panels locked, hidden, where panels are not accessable and on and on where a panel is not readily accessable, breakers are not designed try o be an emergency disconnect, etc. Therefore a main breaker in a subpanel is never a consideration.
The NEC are minimum requirements. Remember that common sense is not a requirement of the NEC where by providing something more than the NEC requires makes sense such as simply adding more outlets, quadraplex outlets all in an attempt to eliminate the need for extension cords and power strips, a main breaker in a subpanel, as long as they are within the code and cost is not a factor.

 

[jap]

Yes, right on, and in addition to there are those who are clueless as to the testing requirements that breakers must pass in before they are blessed with a UL489 listing.
A breaker not being able to be used as a disconnecting means is amusing. And NEC art 230.41 and 42 must be senseless that there must be needs to be able to shut all the power to the building with 6 throws of the hand.e foolish an not required where it needs to be able to shut all the power to the building with 6 throws of the hand.
The point that I was trying to make was to indicate why a main breaker in a subpanel is desirable, though not required, but there are those who think it is a foolish idea which is obvious because of the excuses that they are most likely behind locked doors, panels locked, hidden, where panels are not accessable and on and on where a panel is not readily accessable, breakers are not designed try o be an emergency disconnect, etc. Therefore a main breaker in a subpanel is never a consideration.
The NEC are minimum requirements. Remember that common sense is not a requirement of the NEC where by providing something more than the NEC requires makes sense such as simply adding more outlets, quadraplex outlets all in an attempt to eliminate the need for extension cords and power strips, a main breaker in a subpanel, as long as they are within the code and cost is not a factor.

I-wire never said a breaker could not be used as a means of disconnect.

JAP>

 

[templdl]

I-wire never said a breaker could not be used as a means of disconnect.

JAP>

I was very surprised to this statement on post #22 though."The bottom line is the NEC does not intend breakers to be used as emergency manual shut offs." As often happens iwire may be thinking of something else that be misunderstood by others as often happens to others also.
Breakers are commonly operated manually if there is a situation that one would be determined is an emergency. They could have a shunt trip or under voltage release option which when activated trip the breaker. Motor solenoid operators are also available that allow the breaker to be open and close remotely.
I agree that the term "emergency" often can mean different things to different people. Does that mean that if you determine a need to open a breaker immediately manually because of what may be determine as a critical situation or trip the breaker with an emergency push button to trip the breaker remotely.

 

[jap]

I was very surprised to this statement on post #22 though."The bottom line is the NEC does not intend breakers to be used as emergency manual shut offs." As often happens iwire may be thinking of something else that be misunderstood by others as often happens to others also.
Breakers are commonly operated manually if there is a situation that one would be determined is an emergency. They could have a shunt trip or under voltage release option which when activated trip the breaker. Motor solenoid operators are also available that allow the breaker to be open and close remotely.
I agree that the term "emergency" often can mean different things to different people. Does that mean that if you determine a need to open a breaker immediately manually because of what may be determine as a critical situation or trip the breaker with an emergency push button to trip the breaker remotely.

It means both.

JAP>

 

[charlie b]

I am with Iwire on this subject (a rare, but not unheard of thing :happyyes: ). But let me offer my opinion in a different way. If I am in my own home, standing in either the dining room or the kitchen, which would put me within 10 feet of the one and only panel in the building, and if I have reason to believe someone is receiving an electrical shock, then I absolutely will open the panel cover and hit the main breaker. And that absolutely will terminate the shock event. At that moment, I will also be standing within three feet of the home security system's panel. That has a battery backup, and I would use that system to contact the monitoring company, who would call for medical help. So yes, a main breaker can be used, in a life-threatening emergency, to terminate the shock event.

All that said, everything is different in a public building. Iwire has already explained why. I will only echo that the reason we install breakers in general, and main breakers in particular, has nothing to do with the ability to turn them off in an emergency. A branch or feeder breaker's primary role is to protect the downstream wire against overcurrent. A panel's main breaker's primary role is to protect the panel itself against overcurrent. All these breakers have the secondary role of keeping a circuit turned off during maintenance.

 

[templdl]

I am with Iwire on this subject (a rare, but not unheard of thing :happyyes: ). But let me offer my opinion in a different way. If I am in my own home, standing in either the dining room or the kitchen, which would put me within 10 feet of the one and only panel in the building, and if I have reason to believe someone is receiving an electrical shock, then I absolutely will open the panel cover and hit the main breaker. And that absolutely will terminate the shock event. At that moment, I will also be standing within three feet of the home security system's panel. That has a battery backup, and I would use that system to contact the monitoring company, who would call for medical help. So yes, a main breaker can be used, in a life-threatening emergency, to terminate the shock event.

All that said, everything is different in a public building. Iwire has already explained why. I will only echo that the reason we install breakers in general, and main breakers in particular, has nothing to do with the ability to turn them off in an emergency. A branch or feeder breaker's primary role is to protect the downstream wire against overcurrent. A panel's main breaker's primary role is to protect the panel itself against overcurrent. All these breakers have the secondary role of keeping a circuit turned off during maintenance.

Like a lot of things it is not a good idea to generalize as I did. By adding a main breaker to a subpanel board adds industrian can be extremely expensive. Generally I would like to understand that there would be an authorized person on staff of that is familiar with and knows how to access the equipment. Not every Joe Smow would have a clue.
I think the addition of a main breaker in a sub panel may be a consideration dependent upon ilocation, the type of facility and how it is staffed. Large homes that require multiple loadcenters may as LSO be a consideration since the home owner may not have a clue about where the main loadcenter is located and the difference in it and the. Subpanel that there may be.

 

[iwire]

I think folks are underestimating how fast electricity is compared to humans.