# relay question



## UpInU Electric (Mar 21, 2011)

I have a door that is being held open via a relay in the fire alarm panel right now. My boss wants me to interupt the circut with a relay controlled by a time clock so the door will not stay open 24 hours a day. I need to feed the time clock with 120 V, and on the load side hit a transformer to step the voltage down to 24 V. From that point I need to set a relay and wire it NO. That way when the time clock goes off it will close the relay which in turn will close the door. My question is what type of relay would I need, SPDT or DPDT and how do I interupt the 24 V coming from the fire alarm panel and down to the door openers. I do not have to worry about calling out the fire alarm or disconnecting anything because it is not addressable.


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## steelersman (Mar 15, 2009)

UpInU Electric said:


> I have a door that is being held open via a relay in the fire alarm panel right now. My boss wants me to interupt the circut with a relay controlled by a time clock so the door will not stay open 24 hours a day. I need to feed the time clock with 120 V, and on the load side hit a transformer to step the voltage down to 24 V. From that point I need to set a relay and wire it NO. That way when the time clock goes off it will close the relay which in turn will close the door. My question is what type of relay would I need, SPDT or DPDT and how do I interupt the 24 V coming from the fire alarm panel and down to the door openers. I do not have to worry about calling out the fire alarm or disconnecting anything because it is not addressable.


Single pole relay should work. And I don't see why you need a transformer. Just use a relay with a coil rated for 120Volts.


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## gizmo21187 (Aug 11, 2010)

steelersman said:


> Single pole relay should work. And I don't see why you need a transformer.


Silly question is the entire door beeing supplied by the panel. If so. Just us a 120 relay. I don't think so it should be dc. But there are diff systems out there.
And how many wires go to the panel from the door.

We

Silly rabit, crack kills, i think

Sent from my M80 using a lighter.


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## HARRY304E (Sep 15, 2010)

gizmo21187 said:


> Silly question is the entire door beeing supplied by the panel. If so. Just us a 120 relay. I don't think so it should be dc. But there are diff systems out there.
> And how many wires go to the panel from the door.
> 
> We
> ...


 Are you having fun _gizmo:laughing:_


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## HARRY304E (Sep 15, 2010)

UpInU Electric said:


> I have a door that is being held open via a relay in the fire alarm panel right now. My boss wants me to interupt the circut with a relay controlled by a time clock so the door will not stay open 24 hours a day. I need to feed the time clock with 120 V, and on the load side hit a transformer to step the voltage down to 24 V. From that point I need to set a relay and wire it NO. That way when the time clock goes off it will close the relay which in turn will close the door. My question is what type of relay would I need, SPDT or DPDT and how do I interupt the 24 V coming from the fire alarm panel and down to the door openers. I do not have to worry about calling out the fire alarm or disconnecting anything because it is not addressable.


You just want a normally open relay...:thumbsup:


I am not familer with SPDT or DPDT :blink:

Can you define that please.

It is probably plain as day and i am just missing it.:laughing:


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## gizmo21187 (Aug 11, 2010)

HARRY304E said:


> Are you having fun gizmo:laughing:


Yes

We

Silly rabit, crack kills, i think

Sent from my M80 using a lighter.


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## HARRY304E (Sep 15, 2010)

gizmo21187 said:


> Yes
> 
> We
> 
> ...


Good....:thumbup::thumbup::laughing::laughing:


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## gizmo21187 (Aug 11, 2010)

HARRY304E said:


> You just want a normally open relay...:thumbsup:
> 
> I am not familer with SPDT or DPDT :blink:
> 
> Can you define that please. :


Pm i can snd u some links on that

We

Silly rabit, crack kills, i think

Sent from my M80 using a lighter.


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## HARRY304E (Sep 15, 2010)

gizmo21187 said:


> Pm i can snd u some links on that
> 
> We
> 
> ...


Ok cool..:thumbsup:


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## Jlarson (Jun 28, 2009)

HARRY304E said:


> I am not familer with SPDT or DPDT :blink:


SPDT (Single Pole Double Throw) is a common and a NO and NC terminals that share that common, also called a "Form C" contact. A SPST (Single Pole Single Throw) would just have a common and one other terminal, these are sometimes called "Form A" or Form B" depending on if it's NO or NC.

DPDT (Double Pole Double Throw) two separate commons that each have a NO and NC sharing each common, so two Form C's.


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## gizmo21187 (Aug 11, 2010)

Post pics i can't now seeing aids in under standing i say

We

Silly rabit, crack kills, i think

Sent from my M80 using a lighter.


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## HARRY304E (Sep 15, 2010)

Jlarson said:


> SPDT (Single Pole Double Throw) is a common and a NO and NC terminals that share that common, also called a "Form C" contact. A SPST (Single Pole Single Throw) would just have a common and one other terminal, these are sometimes called "Form A" or Form B" depending on if it's NO or NC.
> 
> DPDT (Double Pole Double Throw) two separate commons that each have a NO and NC sharing each common, so two Form C's.


:laughing:

Man I'm dumb.:blink:

The abbreviations cought off gaurd..:laughing::laughing:

Thanks Jlarson..:thumbup:


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## HARRY304E (Sep 15, 2010)

gizmo21187 said:


> Post pics i can't now seeing aids in under standing i say
> 
> We
> 
> ...


Yeah i know what you meen..:thumbup::laughing::laughing::thumbup:


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## UpInU Electric (Mar 21, 2011)

The reason Im using a transformer is because the 24 volts from the fire alarm is what is being used to hold the door open now. The goal is to maintain the fire alarm panel as the override to keep the doors open or closed, based on whether or not the panel is in trouble obviously. They want a time clock because after certain hours in the day, they dont want people looking inside the room. So i have 24 volts from the fire alarm panel going to the door opener now. I need to interrupt that with this relay which is controlled by the time clock.


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## gizmo21187 (Aug 11, 2010)

Put relay inline from door to panel.

Use a NC relay so that when the clock switches on it will turn to open and cut power to door and close. And when clock turns off now relay becomes closed and the panel now takes over.

That way if the clock is off the panel is boss, and when the clock is on the doors are shut, and if the panel tries closeing door (shut off door power) their all redy shut. And if u have a power failer the panel takes over.

And if you don't need or want use of the relay wells its a NC so just shut the power to the clock

2305

1909121225-1801020920-0318010311-110912120519

19051420-06181513-1325-1380-2119091407-01-12090708200518


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## Mike in Canada (Jun 27, 2010)

Is the time clock pre-existing? If not then I'd be seriously tempted to replace the whole mess with a pico-class smart relay. They have real-time clocks in them.


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## johnsmithabe (May 3, 2011)

a confused question !


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## johnsmithabe (May 3, 2011)

really informative.
Thanks


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## williamj (Nov 10, 2009)

There are 2 problems with this whole scenerio. One is the local fire marshall would probably have a HUGE issue with this and secondly someone is going to have to re-open the doors every day. I don'y know it maybe me but I think they need to find a different way to do what they want. What you are wanting to do electrically is easy but the practicality and legality of it are way different. I think you need to consult the fire marshal in your area and see what he thinks.


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## sbrn33 (Mar 15, 2007)

OK , I'll bite. Why would the fire Marshall have a problem with the fire doors closing? Isn't that what the fire alarm would do?


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## williamj (Nov 10, 2009)

You'll bite?


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## williamj (Nov 10, 2009)

yes when it is in alarm that is what it would do... come on man!


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## sbrn33 (Mar 15, 2007)

So why would he care if they closed the doors then?


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## tombs (May 26, 2011)

is the relay (existing) controlling the door locks or do they control door open magnets that release the door from the open position? If the doors close and lock it might be a problem for fire personel or escape paths for the occupants. Here, any changes to the existing fire system must go thru the Fire Marshal.


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## dronai (Apr 11, 2011)

UpInU Electric said:


> The reason Im using a transformer is because the 24 volts from the fire alarm is what is being used to hold the door open now. The goal is to maintain the fire alarm panel as the override to keep the doors open or closed, based on whether or not the panel is in trouble obviously. They want a time clock because after certain hours in the day, they dont want people looking inside the room. So i have 24 volts from the fire alarm panel going to the door opener now. I need to interrupt that with this relay which is controlled by the time clock.


 
It sounds like you've got it figured out ! TC to the Relay coil, 24V to the door. SPST N/O contactor. 12V trans as needed.

*The tip about the fire marshall sounds like a smart thing to check out


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