1 Pole GE Shunt Trip Breaker

[yahya176]

Hi, I hope all is well. I notice some post about the subject matter. However, I'm trying to avoid installing sub panel and main shunt and wanted to know Is it acceptable to use a single pole 120v coil type shunt trip breaker for shunt trip requirements for fire suppression? Do I wire it in across micro switch or on a set of aux contacts on contactor? the I have small restaurant job. In which, the wiring for the hood is needed; (1- Exhaust Fan 120v 1ph, 1-MUA 120v 1ph, 2-Receptacle circuits for 2-fryer and lights under hood). The mechanical contractor only provided 1- micro switch. I understand the MAU, receptacles and lights must be denergized by the closing of micro switch. The exhaust fan must remain on. I have two 120v DP contactors provided for (1) MAU and lights controlled by switch and (2) receptacle circuits on "constant" at the other? The exhaust fan is controlled by separate switch. I hope this helps! I'm just not sure if it is acceptable to d-energize the fire control panel circuit only to fulfill the shunt trip requirements. Please advise me, any information to the subject will be greatly appreciated. Thank you in advance. :?

 

[LarryFine]

This is my specialty. You don't really need the shunt-trip breaker, but you can use it if you really want to. It's usually used for appliance shut-off, but you have only one, but two appliances. Some can not have the trip coil constantly energized, so must be supplied by the same circuit they supply.

Meanwhile, a couple of questions:

Are the two fryers 120v? Can two be supplied by a single 120v circuit, or is the current too high?

Exhaust fan, make-up air fan, lights. How many switches do you want or need for these?

Is there a horn/strobe? How about any gas-fired appliances?

Will you need to make sure the fryers can not run unless the exhaust is on?

Must the exhaust automatically start with heat under the hood (called "night mode")?

 

[yahya176]

This is my specialty. You don't really need the shunt-trip breaker, but you can use it if you really want to. It's usually used for appliance shut-off, but you have only one, but two appliances. Some can not have the trip coil constantly energized, so must be supplied by the same circuit they supply.

Meanwhile, a couple of questions:

Are the two fryers 120v? Can two be supplied by a single 120v circuit, or is the current too high?

Exhaust fan, make-up air fan, lights. How many switches do you want or need for these?

Is there a horn/strobe? How about any gas-fired appliances?

Will you need to make sure the fryers can not run unless the exhaust is on?

Must the exhaust automatically start with heat under the hood (called "night mode")?

Ans.: Yes, 2 fryers
The fryers are 1500 watt and on a dedicated circuit
There are 2 switches located on the hood
No, strobe/horn
There are gas fired appliances too
Not sure if I need to make fryers run with exhaust?? "No Specs included"
Night mode not stated by building inspector or fire marshal "No specs included"

 

[LarryFine]

I am making a wiring diagram for you, but I may have to modify it, depending on the answers to the following:

Ans.: Yes, 2 fryers. The fryers are 1500 watt and on a dedicated circuit.

Use a simple 2-pole contactor with adequate current rating, with each pole controlling one fryer.

There are 2 switches located on the hood

Use one switch for both fans, the other for hood lights.

There are gas fired appliances too

Electric or mechanical valve? Here, if mechanical, a T-stat and 10-minute timer are required. Let me know.

Not sure if I need to make fryers run with exhaust?

Find out. Works with T-stat in duct and timer above if fryers are operated without exhaust running.

Night mode not stated by building inspector or fire marshal.

Same answer. If mechanical gas valve, T-stat may be required. If electrical gas valve, there will be a reset box, and exhaust must be on first.

A lot depends on whether the gas appliances have standing pilots or electronic ignition, and the desires of the restaurant owner.

 

[LarryFine]

Here is a diagram I made years ago that someone found and posted on another site:



The upper half is what you need to operate the two fans on one switch. On the micro-switch, N is the N/C terminal (normal), E is the N/O terminal, (emergency), and C is the common terminal. The Intake and Exhaust can either be the motors themselves (if they can run on a single circuit), or contactor coils (if they can not). To add the lights, connect the hot side of the light switch to the same micro-switch terminal that feeds the Intake.

When the system trips, the micro-switch removes the connection to the make-up air fan and bypasses the manual fan switch. If they want separate switches for each fan, I can do that, too.

To control the fryers, connect a 2-pole contactor to the same point, using one pole for each fryer circuit, but understand they'll only operate when the blowers are running. If they need to be powered all the time (except for a tripped condition, of course) then you'll need to add a contactor to "multiply" the single set of contacts for that use. Let me know, and I'll make and post a new diagram.

 

[yahya176]

Hi, there are mechanical gas valves and let’s assume fryers need to be run with exhaust fan. The gas fryers have standing pilots. As far as the owner I don’t believe they knows what he wants in that regard. It’s a one of those situations where everyone is clueless including myself :? BTW I saw that schematic on line. It’s very popular. I used it as an example, myself. Also the building inspector/electrical inspector wants to see a shunt trip breaker? Thanks again!

 

[dkidd]

Don't trip the exhaust fan.

 

[yahya176]

If the (2) fryers which are corded and plug into dedicated outlets under the hood could be powered all the time, that would be an option as well. Thanks again.

 

[ActionDave]

Also the building inspector/electrical inspector wants to see a shunt trip breaker? Thanks again!

There is no requirement or need for a shunt trip breaker on Ansul systems. I think it is the worst way to do it. I wire them up with contactors the same way Larry diagramed.

 

[kwired]

There is no requirement or need for a shunt trip breaker on Ansul systems. I think it is the worst way to do it. I wire them up with contactors the same way Larry diagramed.

I sort of agree with you on it being worst way to do it. If a switch contact fails or shunt coil is burned out nothing happens (as far as shutting down electric appliances) when the unit is called upon to do it's thing. Using a contactor - it will drop out anytime something fails and users will experience failures and have things serviced. Potential failure of this method is mostly only limited to welding of contacts in the contactor or other mechanical lockup of the contactor.

 

[yahya176]

I sort of agree with you on it being worst way to do it. If a switch contact fails or shunt coil is burned out nothing happens (as far as shutting down electric appliances) when the unit is called upon to do it's thing. Using a contactor - it will drop out anytime something fails and users will experience failures and have things serviced. Potential failure of this method is mostly only limited to welding of contacts in the contactor or other mechanical lockup of the contactor.

I see your point... I thought that micro switch served the same purpose except that you can reset the breaker. How does the micro switch works after it trips?

 

[kwired]

I see your point... I thought that micro switch served the same purpose except that you can reset the breaker. How does the micro switch works after it trips?

Microswitch is only "reset" when the system gets "recharged"

If using the shunt trip breaker you are using the normally open (held open) side of the switch. You don't have just switch failure as a possible fail mode, but if any conductor is "open" back to the shunt coil it is not going to operate the shunt coil, and the breaker isn't going to trip.

With a contactor there is still some risk of failed contact that is "welded" closed, but many other possible fails will be noticed as it won't let the equipment being controlled operate when it fails.

 

[yahya176]

Here is a diagram I made years ago that someone found and posted on another site:

View attachment 20070

The upper half is what you need to operate the two fans on one switch. On the micro-switch, N is the N/C terminal (normal), E is the N/O terminal, (emergency), and C is the common terminal. The Intake and Exhaust can either be the motors themselves (if they can run on a single circuit), or contactor coils (if they can not). To add the lights, connect the hot side of the light switch to the same micro-switch terminal that feeds the Intake.

When the system trips, the micro-switch removes the connection to the make-up air fan and bypasses the manual fan switch. If they want separate switches for each fan, I can do that, too.

To control the fryers, connect a 2-pole contactor to the same point, using one pole for each fryer circuit, but understand they'll only operate when the blowers are running. If they need to be powered all the time (except for a tripped condition, of course) then you'll need to add a contactor to "multiply" the single set of contacts for that use. Let me know, and I'll make and post a new diagram.

Larry, If you get a chance , Please show the wiring. Thanks guys! When the system trips, the micro-switch removes the connection to the make-up air fan and bypasses the manual fan switch. If they want separate switches for each fan, I can do that, too.

To control the fryers, connect a 2-pole contactor to the same point, using one pole for each fryer circuit, but understand they'll only operate when the blowers are running. If they need to be powered all the time (except for a tripped condition, of course) then you'll need to add a contactor to "multiply" the single set of contacts for that use. Let me know, and I'll make and post a new diagram.

 

[LarryFine]

Larry, If you get a chance , Please show the wiring.

Tell me what you need to see. Read through the entire thread again, look at my questions, and let me know exactly how you want to use the system normally (manual daily switching), and what needs to happen when the system trips. When you have only a single micro-switch, you can use contactors to multiply the contacts.

Whatever needs to lose power when the system trips, feed that device's contactor(s) from the micro-switch terminal that has power in the normal (set) position, and whatever needs to be energized when the system trips, feed that device's contactor(s) from the micro-switch terminal that has power in the emergency (tripped) position.