warning light

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  #1  
Old 01-10-14, 04:23 PM
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Angry warning light

long story short, the power went off to our hot tub and if froze in the -5* weather.

what I would like to do is install a warning light that goes ON when the power goes off so this does not happen again. I thought about a light that stays on with the power on, but I don't think that wouild get the attention needed as a light coming on. Any ideas
 
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Old 01-10-14, 05:22 PM
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A normally open relay with a 120v or 240v coil + 12 volt battery + 12 volt LED light.

<img src="https://myphotos.mypclinuxos.com/images/ray2047/alarm.jpg" width="650" height="450"/>
 

Last edited by ray2047; 01-10-14 at 05:57 PM.
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Old 01-10-14, 09:49 PM
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neat idea, any idea where I might find something like this ready made?
 
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Old 01-11-14, 05:39 AM
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That's a rather specialized request especially for a 240 volt circuit. I did a quick search online and could not find one ready made. Luckily it's a really simple circuit and could be made with parts ordered online.

Most important would be to get a continuous duty relay that has normally closed (NC) contacts. If a single pole single throw (SPST) NC relay is hard to find you can use a relay that has more contacts. You would just use the NC contacts and leave the others unused.

It's also possible that the controls for your spa already have a relay with NC contacts that are not being used. Some spas have a master relay as part of their safety circuit that kills power to the entire spa when you open the cabinet door.
 
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Old 01-11-14, 08:29 AM
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You need a relay that is open when energized. Here is an example: 90295Q 208/240V Coil SPDT Relay note only one set of contacts would be used. With this relay it would be either 5 or 4.
 

Last edited by ray2047; 01-11-14 at 08:57 AM.
 

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