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Discussion Starter · #1 ·
I have a customer who wants three pool pump safety switches wired to one buzzer. - I told him I am not sure I will be able to do this. I want to try and keep this simple. Each safety switch has one set of 24 volt contacts for a remote alarm, (buzzer).

Let's say the buzzer has one set of inputs. I don't want to back-feed any of the other safety switches should one of the switches activate the buzzer. I'm not used to working with low voltage systems like this and I am wondering what the best way to accomplish this is. If I had a wiring diagram I am pretty sure I could accomplish this, but the diagrams that come with the equipment show only one buzzer per switch. Any ideas?
 

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Discussion Starter · #3 ·
what would happen if two pump safety switches were activated at the same time? would there be a possibility of back-feeding the safety switch contacts? ....hmmmm having trouble thinking this one through.
 

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Discussion Starter · #4 · (Edited)
you could do it with a couple of relays....but I think the best setup would be to have 1 buzzer and 3 indicating lights so you know which unit has tripped the safety switch. Do these switches have dry contacts?
I believe the 24 volt contacts for the remote alarm are dry contacts... although I am not completely clear on what that means. I am reading that from the manual.
The manual says, "Alarm - dry contact that closes while the SR500 is in an alarm state, or in maintenance mode...."
 

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I believe the 24 volt contacts for the remote alarm are dry contacts... although I am not completely clear on what that means. I am reading that from the manual.
The manual says, "Alarm - dry contact that closes while the SR500 is in an alarm state, or in maintenance mode...."
that's your dry contact.

just wire in parallel with one voltage source to activate buzzer (and indicator for which switch as others said).
 

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Discussion Starter · #7 · (Edited)
that's your dry contact.

just wire in parallel with one voltage source to activate buzzer (and indicator for which switch as others said).
While i like the idea of the indicator, it's not in the bid... I am being subcontracted and I have to do this according the the contractor's specs. The contractor has asked if I can wire all three switches into one buzzer. Honestly, I am not sure how to do this. I am not sure how I can have only one voltage source for the buzzer when three separate buzzers (each being a voltage source) needs to activate the same buzzer. - I would love to know how to do this.

What would the voltage at the buzzer be if two switches were sending 24V to the buzzer at the same time? I can't answer this question. I probably should know the answer but I don't. My guess is that the voltage would still be parallel at that point, and, therefore, you would only read 24 volts which should cause no harm to the buzzer.
 

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Discussion Starter · #8 ·
A dry contact is just a switch. It is isolated from the triggering device electrically. If all three safety devices are dry contacts, then just connect them in parallel.
What would happen if two switches went off simultaneously? The "dry" contacts would no longer be "dry"... Am I correct? I am thinking you would end up back-feeding the switch.

Someone else put these switches in and burned them up... I don't want this to happen. That is why I am being real careful here.
 

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Paul S. said:
What would happen if two switches went off simultaneously? The "dry" contacts would no longer be "dry"... Am I correct? I am thinking you would end up back-feeding the switch. Someone else put these switches in and burned them up... I don't want this to happen. That is why I am being real careful here.
what happens when you put two switches in parallel to control a light? You only need one power source. 3 switches in parallel and one buzzer. If you still can't grasp the concept of a dry contact, then ou better hire an electrician.
 

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dude, you need 3 sets of wires for your switches (3 pairs). wire to one location, where there is one buzzer and one supply. don't know how else to say it.
 

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Discussion Starter · #11 ·
what happens when you put two switches in parallel to control a light? You only need one power source. 3 switches in parallel and one buzzer. If you still can't grasp the concept of a dry contact, then ou better hire an electrician.
Okay, so it seems that if I feed the buzzer from two separate 24vac sources that would not harm the buzzer. Nor, should it harm the safety switches in any manner should two switches be sending 24 volts to the buzzer at the same time.
 

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drew this up real quick...you would need four relays....the buzzer would latch until you hit the silence button after the safety switches have been opened. you could add latching contacts to the indicator lights also. Unless the safety switches have some sort of indication as to which one has tripped the indicator lights are a good idea.
 

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Paul S. said:
Okay, so it seems that if I feed the buzzer from two separate 24vac sources that would not harm the buzzer. Nor, should it harm the safety switches in any manner should two switches be sending 24 volts to the buzzer at the same time.
you said they are dry contacts. They are not power sources.
 

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Discussion Starter · #17 ·
View attachment 35982


drew this up real quick...you would need four relays....the buzzer would latch until you hit the silence button after the safety switches have been opened. you could add latching contacts to the indicator lights also. Unless the safety switches have some sort of indication as to which one has tripped the indicator lights are a good idea.
Thank you!
 

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Discussion Starter · #20 · (Edited)
If you are using the device I think you are, then terminals 7 and 8 provide your 24 volts. Terminals 5 and 6 are your dry contacts for alarm. Only use terminals 7 and 8 for you supply voltage from one unit only.
Now you're talking! I'll have to look at the manual, but just seeing your post; that seems to make sense. It's a Stingl SR500 pool pump safety switch. (Safety Vacuum Relief System)

I haven't had time to digest the whole manual; I did call the manufacturer and I am still awaiting a call back from them. - My only concern here is that if one of the pumps is switched off for maintenance the other's would loose their warning system. (The ability to activate the buzzer.) If this, in fact, works then I would have to make sure the pump maintenance disconnect is located after the safety switch.... and hopefully they don't use the breaker as a disconnect thereby taking away the source voltage for the buzzer.... Just thinking out loud here.
 
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