correctly wire fire suppression without use of shunt breakers

Im a residentual electrican and doing a commercial job that i have to wire fire compression system. I would like to do so without the st breakers. system has exaust, supply and hood lights. no under hood recepticles. Fire box contains 2 micro switches. How can i wire this with the use of contactors? Thank you and if more info is needed i can provide
 

hillbilly1

Senior Member
All appliances under the hood gas? The mechanical contractor will probably have an electric gas valve installed, or a mechanical one that is tripped by the fire suppression system, in the case of the mechanical valve, you will only need to shut down the make up air fan, and possibly start the exhaust fan depending on local codes.
 

iwire

Moderator
Staff member
Short answer, yes you can do it with contactors..


Of course I can't help but wonder why you want to go a much more expensive route.
 
All appliances under the hood gas? The mechanical contractor will probably have an electric gas valve installed, or a mechanical one that is tripped by the fire suppression system, in the case of the mechanical valve, you will only need to shut down the make up air fan, and possibly start the exhaust fan depending on local codes.
yes that's all i have to do is stop mua and start exaust. if exhaust not already running. i need to know in detail how to achieve using contractors
 
All appliances under the hood gas? The mechanical contractor will probably have an electric gas valve installed, or a mechanical one that is tripped by the fire suppression system, in the case of the mechanical valve, you will only need to shut down the make up air fan, and possibly start the exhaust fan depending on local codes.
Short answer, yes you can do it with contactors..


Of course I can't help but wonder why you want to go a much more expensive route.
what its the cost efficient way?
 

hillbilly1

Senior Member
yes that's all i have to do is stop mua and start exaust. if exhaust not already running. i need to know in detail how to achieve using contractors
That is easy, use a DPDT power relay (one with sufficent HP rating) wire the coil to the microswitch where when the fire suppression system is armed, the contact is closed. Wire the MUA fan switch in series with the relay switch using the normally open contact on one pole, while wiring the exhaust fan switch in parallel with it's control switch (hood switches) If the motors are 240, use two power relays. If they are three phase, tie into the control circuit for the starter. This will give you a fail safe, if for some reason the relay control power is turned off, the fans default to MUA off, exhaust on.
 
That is easy, use a DPDT power relay (one with sufficent HP rating) wire the coil to the microswitch where when the fire suppression system is armed, the contact is closed. Wire the MUA fan switch in series with the relay switch using the normally open contact on one pole, while wiring the exhaust fan switch in parallel with it's control switch (hood switches) If the motors are 240, use two power relays. If they are three phase, tie into the control circuit for the starter. This will give you a fail safe, if for some reason the relay control power is turned off, the fans default to MUA off, exhaust on.
this is the diagram
 

Attachments

That is easy, use a DPDT power relay (one with sufficent HP rating) wire the coil to the microswitch where when the fire suppression system is armed, the contact is closed. Wire the MUA fan switch in series with the relay switch using the normally open contact on one pole, while wiring the exhaust fan switch in parallel with it's control switch (hood switches) If the motors are 240, use two power relays. If they are three phase, tie into the control circuit for the starter. This will give you a fail safe, if for some reason the relay control power is turned off, the fans default to MUA off, exhaust on.
also how will it be possible to exaust without running mua in normal conditions
 

hillbilly1

Senior Member
In normal conditions, the MAU normally runs, this is to reduce loss of conditioned air in the kitchen, otherwise a separate switch would be required. This manufacture is doing something different than everybody else, because most micro switches are only rated for 6-10 amps, not 20 like the manufacture is stating. If what the manufacture says is true, then you can directly use the micro switch to override the wall switch if the motor is less than 1 HP, and since in this instance the MAU is not required to be shut down, only one contact will be needed. The fans should be on separate circuits, so the control switch will have to be double pole, due to the plans calling for one switch.
 
In normal conditions, the MAU normally runs, this is to reduce loss of conditioned air in the kitchen, otherwise a separate switch would be required. This manufacture is doing something different than everybody else, because most micro switches are only rated for 6-10 amps, not 20 like the manufacture is stating. If what the manufacture says is true, then you can directly use the micro switch to override the wall switch if the motor is less than 1 HP, and since in this instance the MAU is not required to be shut down, only one contact will be needed. The fans should be on separate circuits, so the control switch will have to be double pole, due to the plans calling for one switch.
this is what i have so far. i have 2 circuits feeding a double pole breaker. one for mua and one for exhaust and light. thats how i interpret it to be on diagram. is that correct so far? i have purchased 2 20 amp double pole contactors. and a junction box to put them in. i plan on bringing power from switch to contactors and thats about when im getting a bit confused. the fire suppression ppl have not set there box yet so im have hard time visualizing what my next steps should be. now the top end as far as wiring to the disconnect and fans make sense. and i do understand that i will need a seperate junction for micro switches because you cant junction in that box. its the switch to contactor to fire box that im not all the way grasping.
 
In normal conditions, the MAU normally runs, this is to reduce loss of conditioned air in the kitchen, otherwise a separate switch would be required. This manufacture is doing something different than everybody else, because most micro switches are only rated for 6-10 amps, not 20 like the manufacture is stating. If what the manufacture says is true, then you can directly use the micro switch to override the wall switch if the motor is less than 1 HP, and since in this instance the MAU is not required to be shut down, only one contact will be needed. The fans should be on separate circuits, so the control switch will have to be double pole, due to the plans calling for one switch.
so coming from panel i have two separate circuits feeding through both sides of double pole switch. is that ok? or switch is only suppose to trigger contractors
 

augie47

Moderator
Staff member
this is what i have so far. i have 2 circuits feeding a double pole breaker. one for mua and one for exhaust and light. thats how i interpret it to be on diagram. is that correct so far? i have purchased 2 20 amp double pole contactors. and a junction box to put them in. i plan on bringing power from switch to contactors and thats about when im getting a bit confused. the fire suppression ppl have not set there box yet so im have hard time visualizing what my next steps should be. now the top end as far as wiring to the disconnect and fans make sense. and i do understand that i will need a seperate junction for micro switches because you cant junction in that box. its the switch to contactor to fire box that im not all the way grasping.
What I normally see is a handy box nippled into the knockout at the fire suppression switch with connections made there and conductors run to your contactor location.
There are a number of routes you can take to reach your goal, but rather than re[inventing the wheel, the simplest might be to use Larry Fine's "after" diagram with the "Intake Fan" and "Exhaust fan" being your two contactors. Larry's "Hot" could come from either of your two supply breakers if properly sized to protect the control wiring or from a third source.
If you need to control receptacles/appliances you can use shunt trip breakers or additional contactors and Larry's hand-drawn diagram.
 
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hillbilly1

Senior Member
this is what i have so far. i have 2 circuits feeding a double pole breaker. one for mua and one for exhaust and light. thats how i interpret it to be on diagram. is that correct so far? i have purchased 2 20 amp double pole contactors. and a junction box to put them in. i plan on bringing power from switch to contactors and thats about when im getting a bit confused. the fire suppression ppl have not set there box yet so im have hard time visualizing what my next steps should be. now the top end as far as wiring to the disconnect and fans make sense. and i do understand that i will need a seperate junction for micro switches because you cant junction in that box. its the switch to contactor to fire box that im not all the way grasping.
As Augie said, most fire suppression systems have the junction box factory mounted, so your terminations will be in there. Think of it this way, you bring your control circuit for the contactors to the common of the microswitch, from the normally closed contact, you power the coil for the exhaust fan contactor, in turn it's contacts parrallel the on/off switch you installed feeding the exhaust fan. Then off the normally open side of the microswitch, power the MAU contactor coil, it's contact will be in SERIES with the on/off switch you installed feeding the MAU and you are done.
Keep in mind that the microswitch state is when at rest, if the system is "armed" or "cocked", the contacts will read the opposite of what I have told you if ohm it out.
 
As Augie said, most fire suppression systems have the junction box factory mounted, so your terminations will be in there. Think of it this way, you bring your control circuit for the contactors to the common of the microswitch, from the normally closed contact, you power the coil for the exhaust fan contactor, in turn it's contacts parrallel the on/off switch you installed feeding the exhaust fan. Then off the normally open side of the microswitch, power the MAU contactor coil, it's contact will be in SERIES with the on/off switch you installed feeding the MAU and you are done.
Keep in mind that the microswitch state is when at rest, if the system is "armed" or "cocked", the contacts will read the opposite of what I have told you if ohm it out.
thank you guys so much for the help. i successfully were able to get the system to function as it should. but i do have one more prob. the exhaust is pulling like 40(amps but only should be pulling 10. i have 110 going to motor like plate asks for and its rotating counter clockwise like it should. is there a possibility that something on my part could be causing this
 
As Augie said, most fire suppression systems have the junction box factory mounted, so your terminations will be in there. Think of it this way, you bring your control circuit for the contactors to the common of the microswitch, from the normally closed contact, you power the coil for the exhaust fan contactor, in turn it's contacts parrallel the on/off switch you installed feeding the exhaust fan. Then off the normally open side of the microswitch, power the MAU contactor coil, it's contact will be in SERIES with the on/off switch you installed feeding the MAU and you are done.
Keep in mind that the microswitch state is when at rest, if the system is "armed" or "cocked", the contacts will read the opposite of what I have told you if ohm it out.
thank you guys so much for the help. i successfully were able to get the system to function as it should. but i do have one more prob. the exhaust is pulling like 40(amps but only should be pulling 10. i have 110 going to motor like plate asks for and its rotating counter clockwise like it should. is there a possibility that something on my part could be causing this
 
Ansul Wiring Diagram

Ansul Wiring Diagram

A customer has requested a wiring diagram for the Ansul system I installed. Their "electrician" insists on it. Im never asked to provide and the Ansul manual does not provide anything but a small diagram for the Microswitches. Can you provide a diagram to shutdown a 110 receptactle for 1 switch and a 220 plug for the other switch. This is an old building and shunt trip breaker will not work.
 

kwired

Electron manager
A customer has requested a wiring diagram for the Ansul system I installed. Their "electrician" insists on it. Im never asked to provide and the Ansul manual does not provide anything but a small diagram for the Microswitches. Can you provide a diagram to shutdown a 110 receptactle for 1 switch and a 220 plug for the other switch. This is an old building and shunt trip breaker will not work.
We can give you wiring diagrams of different ways to make such an installation, only you know exactly what you installed. I would assume they want the diagram to match what you did, otherwise it has little meaning.
 

PetrosA

Senior Member
thank you guys so much for the help. i successfully were able to get the system to function as it should. but i do have one more prob. the exhaust is pulling like 40(amps but only should be pulling 10. i have 110 going to motor like plate asks for and its rotating counter clockwise like it should. is there a possibility that something on my part could be causing this
Are you sure you didn't have your clamp meter set to MIN/MAX mode? That sounds like a startup (inrush) reading to me. If it isn't, and you have it on a 20A breaker like you said, it shouldn't take long to trip the breaker. Is that what's happening?
 
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