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#171919 12/08/07 09:42 PM
Joined: Sep 2004
Posts: 174
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bot540 Offline OP
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I need to install a few shunt trip Square D QOB breakers and was wondering how exactly are these things are wired. Off the ansul system I have three wires yellow, brown, and blue. I believe that the yellow is the common and the blue is the normally closed contact, which make the brown the normally open contact.
I am assuming you hook the breaker up to the normally open contact. Is this correct?


Jesus may have been a capenter,but God was an electrician.Genesis1:3
Joined: Aug 2007
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Yellow should be common,brown N/O.
Dedicate a ckt from a NON-shunted panel to this contact. then to the ST brkr/brkrs.On activation the relay closes and shunts the brkr. Panel down.
The exhaust fan/s should not be shunted on deployment.

Joined: Aug 2007
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====The exhaust fan/s should not be shunted on deployment. ==

I'll retract this, untill I can quote the art.
It is common practice, I just can't find it rght now.

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NFPA-17A-
4.4.3.5-- Exhaust fans do not need to be shut down on deployment of the wet system.


But in 5.6.2.2- all fuel and heat sources MUST be shut down.
easy to shunt trip the panel.
4.4.3.4- solid fuel- needs no shut down.Fancy Pizza joint--(Joint mmmm)
4.4.3.7- requires all shut down devices need a manual reset.
shunt trip brkr, coverd.

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bot540 Offline OP
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So the breaker needs a 120 volt signal to trip?


Jesus may have been a capenter,but God was an electrician.Genesis1:3
Joined: Jul 2002
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The shunt trips I've wired need 120v signal to trip

Joined: Dec 2000
Posts: 4,287
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I much prefer using a contactor instead of shunt trip breakers.
They don't take up valuable space in the panel (shunt trips take an extra pole space for the trip), and are more economical.

Joined: Aug 2007
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Agree, if you only have a few peices of equipment to shut down, contactor may be more economic.
Most gas equip. will have a mechanicle gas valve shut off.

Only the equipment in the protected area (hazard) needs to be dumped. Check your local codes and follow specs.

Last edited by leland; 12/09/07 10:13 AM.
Joined: Mar 2005
Posts: 1,213
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Originally Posted by walrus
The shunt trips I've wired need 120v signal to trip
I've seen some with 24VDC and 48VDC shunt trip- you'd need to check the specs on the breaker as to what it needs.

Should be OK to feed shunt-trip from this panel. After all, it will have power TO shunt trip, and after shunt trip... you don't really need power anymore!

Also, you might want to note somewhere on the panel that it's configured to shunt trip. We had one go off once over lunch when a contractor working sprinklers in another part of the building opened a valve just outside a data center to bleed the system and a flow sensor shunt-tripped the main breaker and killed power to the data center. DOH! None of the ITs had any clue what had happened or how to recover, and were running around trying to figure out why the generator hadn't started. - NOTHING was labeled, neither the panel nor the sprinkler. It's labeled now.

Last edited by SteveFehr; 12/09/07 11:06 AM.
Joined: Aug 2007
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I've done that! Wow,they don't like it much.
Coz everybody looses 10, mil$ a minute. Just ask them.

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