Commercial Panels

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sean1

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I am new to the trade, and didn't quite understand my foreman's description. I recently came across a 208 volt 3-phase panel in a commercial application and noticed that there were shunts in it. Was is the definition and purpose of these shunts?
 

infinity

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A shunt trip breaker is designed to be remotely tripped. Usually they appear to have an extra "pole" when mounted within a panelboard, (a three pole shunt trip will occupy four breaker slots in the panel). This extra "pole" typically has two control wires that are used to trip the CB. We have used these devices as part of an Ansul system in restaurants where the activation of the Ansul system will trip the shunt trip CB's.
 

George Stolz

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CHBSH330.JPG


Also, I believe when the fourth pole is energized, it contains a coil that activates the trip mechanism on the breaker.

I haven't had an opportunity to work with these yet, but I may soon... :)
 

sean1

Member
Commercial Panels

Thanks guys. Now I have a couple more questions regarding your responses.
1. What is an Ansul system?
2. Is the "remote trip mechanism" located at the appliance protected? And what does it sense to cause it to trip?
 

iwire

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First keep in mind shunt trip breakers come in many sizes and are used for other purposes than kitchen equipment.

1. What is an Ansul system?

Ansul is a brand name of commercial kitchen hood equipment.

There are manual pull stations and and automatic temp sensors in the exhaust hood that if a fire happens under the hood will release a chemical extinguishing agent to put the fire out.

At the same time you must remove the source of heat from the cooking appliances. If they are gas powered the gas is cut off, if they are electric the power needs to be cut off. This is where a shunt breaker comes in, you could also use a contactor (relay) but they cost much more than a simple shunt trip breaker.

There is a switch in the Ansul control panel that you run 120 volts through and back to the shunt trip breaker. When the ansul system activates it sends a 120 volt signal to the shunt trip breaker causing it to open.
 

sean1

Member
Commercial Panels

Thanks for the info.
When you mentioned that these breakers come in other sizes, do you mean different voltages? And what voltages do they come in? Also, what are the other applications that you mentioned?
 

infinity

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First keep in mind shunt trip breakers come in many sizes and are used for other purposes than kitchen equipment.


This is true. Ansul systems are just one of many shunt trip applications. Another example would be when building IT rooms under NEC Article 645 we use shunt trip main CB's to kill all of the power within the room after the activation of an EPO.
 

sean1

Member
Commercial Panels

Thanks again. As I mentioned, I am new at this & I have borrowed my friend's computer to use this website - which by the way is an excellent website - but I am not familiar with the terms you are using. I think IT is Information Technology, but I don't know what EPO is. Can you educate me?
I have a thirst for knowledge.
Thanks
 

iwire

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Location
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sean1 said:
Thanks for the info.
When you mentioned that these breakers come in other sizes, do you mean different voltages?

I believe you can get a shunt trip breaker in pretty much any size.

100 amp and below they usually have the 'extra' pole as the one George posted does.

Above 100 amps it is often a shunt trip 'kit' that you can add into the breaker.

Any large breaker with GFP usually comes with shunt trip terminals.


And what voltages do they come in?

The breakers can be any voltage, the shunt trip mechanisms that I have installed have always been 120 volt.


Also, what are the other applications that you mentioned?

As Trever mentioned it might be to shut down a computer room.

Or

To shut down an entire building with a button located at a place that makes the fire dept happy.

Or

I have used shunt trip breakers to provide GFP for heat trace circuits.

Or

To shut down fans / HVAC units when the fire alarm goes off.

The only limit to there uses is the installers imagination.

The advantage to a shunt trip breakers is they are cheaper than contactors and you do not have to install an additional enclosure.

The disadvantage is they are not 'self resetting' once they are tripped you must go to the breaker and reset it just like it tripped on overload.
 

infinity

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sean1 said:
Thanks again. As I mentioned, I am new at this & I have borrowed my friend's computer to use this website - which by the way is an excellent website - but I am not familiar with the terms you are using. I think IT is Information Technology, but I don't know what EPO is. Can you educate me?
I have a thirst for knowledge.
Thanks


Here is a web dictionary definition:

Short for emergency power off; also referred to as an EPO switch. A button or switch that shuts down the power in a room or network of electrical circuits. Typically used in data centers, where there are large amounts of computers using large amounts of electricity, the EPO is meant to be activated by a human only in emergency situations when it is necessary to cut the power if human life is in jeopardy or if there is the potential for major damage to the building or equipment (e.g., in the case of a fire or electrocution). The sudden loss of power will inevitably lead to the loss of some data, and the EPO is not meant to be used under normal circumstances.


Heres an article from APC:

http://www.ptsdcs.com/whitepapers/20.pdf
 

George Stolz

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Windsor, CO NEC: 2017
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To heck with it, I didn't need to reply. You guys had covered the bases. :)

One thing that Sean might not have clear, though. Relays are essentially handy switches that can control voltages other than the switch that the person touches is rated for. A picture may help:

Scotty.jpg

A while back, a member was looking to have a 120V pump come on whenever a low voltage thermostat "closed", or turned on.

If you trace your finger along the circuit paths, you will see how either thermostat in the system, operating at a tiny 24 Volts AC on tiny 18 gauge wire, can be made to control a 120V or 240V or 277V or 480V load, potentially on very large wire.

You see, the only load on the thermostat itself is the little coil in the relay. The coil causes the contacts to close, and in turn completes the controlled circuits.

In the case of the Ansul system, relays are used to do many tasks when only one switch closes.
 

sean1

Member
Commercial Panels

Thanks everybody for all the information you have provided me with. As I said, I borrowed a friend's computer and found this website to be very valuable. I now have enough information to get a better understanding of the function of shunts located in commercial panels.
 

infinity

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Location
New Jersey
Occupation
Journeyman Electrician
hardworkingstiff said:
Where do you get the control power for the "shunt" part of the breaker? From the same circuit breaker or from a seperate control breaker?


If I remember correctly there are both internally and externally powered shunt trip breakers. The internally powered one can be activated by the closing or opening of a dry contact, the externally powered ones are powered by applying voltage to them.
 

iwire

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Location
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hardworkingstiff said:
Where do you get the control power for the "shunt" part of the breaker? From the same circuit breaker or from a seperate control breaker?

All the ones I have done required an external 120 volt source to trip them.

This includes breakers used for 277 and 480 volt circuits.
 

drg

Senior Member
If your using a shunt trip breaker for a ansul fire suppresion system that requires a 120v to activate , do you carry a neutral from the 120v source also?

How is that arranged in the 480v panel ?

While the ansul system has been in some projects that I have been on , first hand I never had to terminate a panel with the shunt trips in them ,I hate to ask but I don't under stand .

In short I am asking how does , or where does the neutral terminate for the shunt trip breaker?
 

iwire

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Location
Massachusetts
I am sure there are a 100 ways to wire them that work fine.

If the panel is 120 we tie one of the shunt trip leads to the neutral bar.

The other side of the shunt is run out to the switches that will activate it.

A hot is either run from the shunt breaker load side if the size is right or the feed is picked up from another breaker. I like to use another circuit that would be missed if it went off.

On the few 480 volt panels I have installed shunt trips in we had to bring a 120 volt control circuit into the 480 panel.
 

drg

Senior Member
OK that helps , I see in your post #6 you explain that the shunt is activated by a heat sensor or manual switch also , that would only seem to make sense.

Next time I'll try and get involved with one these system's , for some odd reason I always seem to be doing something else......they don't sound that complicated but something I would like to put my hands on once , that always makes a big difference in understanding for me.
 
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