# Shunt Trip won't reset



## John15145 (Sep 13, 2015)

I have a Square D shunt trip breaker FJA34030sa if it doesn't reset is it bad


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## John15145 (Sep 13, 2015)

also how do they work, where does the secondary power come from


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## 480sparky (Sep 20, 2007)

It may not reset because there's still power being applied to the trip coil.

Where that power originates is anyone's guess. Fire alarm panel, elevator controls, ansul system, mushroom out at the dispensers, any number of life-safety or other systems.


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## Big John (May 23, 2010)

A shunt-rip is a solenoid that, when energized, puts pressure on the trip latch of the breaker preventing it from closing. Disconnect the wire-nuts to the shunt-trip and see if the breaker resets afterwards. If not, bad breaker.


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## telsa (May 22, 2015)

Big John said:


> Disconnect the wire-nuts to the shunt-trip and see if the breaker resets afterwards. If not, bad breaker.


I'd only risk that if the connected load was locked out// conductors un-landed.

Shunt trip breakers are only ever installed per specification. 

Something's up. 

This breaker has a 120 V shunt circuit. 

So even an influence tester should reveal if the shunt is being activated.


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## Big John (May 23, 2010)

Fair point, without knowing why the breaker is tripped, reclosing might be a bad idea.

But he can still test for power at the shunt-trip circuit. Opening that won't change the condition of the breaker.


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## ponyboy (Nov 18, 2012)

A lot of the shunt trip breakers I do are activated via mushroom head e-stop. Typically you'd think momentary contacts in a nc state but with shunt trips you'll likely find a maintained contact in a no state. Maybe someone bumped the e-stop and you need to find it and pull that bitch back out


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## 480sparky (Sep 20, 2007)

A way to figure out where to start looking is to find out what the breaker serves. :whistling2:


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## Wirenuting (Sep 12, 2010)

ponyboy said:


> A lot of the shunt trip breakers I do are activated via mushroom head e-stop. Typically you'd think momentary contacts in a nc state but with shunt trips you'll likely find a maintained contact in a no state. Maybe someone bumped the e-stop and you need to find it and pull that bitch back out Sent from my iPhone using Tapatalk


Ditto on the mushroom. We also have some of them tied to a rooms fire alarm.


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## John15145 (Sep 13, 2015)

*Shunt trip breaker*

Thanks for your advice, I have the breaker out of the panel and it still will not reset. it's a molded breaker, I guess it bad right lol.


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## ponyboy (Nov 18, 2012)

John15145 said:


> Thanks for your advice, I have the breaker out of the panel and it still will not reset. it's a molded breaker, I guess it bad right lol.



Did you disconnect the shunt contacts? I'd hope so


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## hardworkingstiff (Jan 22, 2007)

ponyboy said:


> Did you disconnect the shunt contacts? I'd hope so
> 
> 
> Sent from my iPad using Tapatalk


I would think if he took it out of the panel he would have disconnected them, but ......... that assume word ...... :laughing:


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## hardworkingstiff (Jan 22, 2007)

John15145 said:


> Thanks for your advice, I have the breaker out of the panel and it still will not reset. it's a molded breaker, I guess it bad right lol.


Makes sense.


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## ponyboy (Nov 18, 2012)

hardworkingstiff said:


> I would think if he took it out of the panel he would have disconnected them, but ......... that assume word ...... :laughing:



I agree but imo that probability that the shunt coil is in a maintained state of actuation is much greater than the breaker simply being bad. 


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## John15145 (Sep 13, 2015)

Thanks again guys


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## MDShunk (Jan 7, 2007)

That's a super high interrupting ability breaker. It might be worth seeing if the field installed shunt kit is available to rehabilitate that breaker. It's a 1,000 dollar breaker.


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