DIY Auto-Top-Off (ATO) System

[JWeb]

Rob, also keep in mind that the float switches have a maximum current rating - which is consumed by the wattage/voltage combinations of all of the equipment running off of that switch. If I remember correctly, most of the float switches I was looking at were rated for 0.7A or so - which is approximately 80 watts at 120V (conservatively). It doesn't take much to use up all of that power. If you exceed the current rating of the switch, it could melt or (possibly worse) have the contacts welded shut - making it no longer a switch (= FLOOD).

(I also agree that stray voltage is still a concern... and although you have heaters and pumps in the sump, they are well designed to handle and isolate the 120V... the float switches are not, IMO.)

Also, I believe that you were looking for a source for latching relays that weren't 30$. If you review my original post in this thread, you will find a link to the latching relay I used for my ATO. I got it from DigiKey.COM and it was cheap - I think 5 or 7$.

Hope this helps...

Jeff.

 

[RobboT]

thanks Jeff, this thread is so long now I didnt even recall that relay link.

 

[RobboT]

OK we can talk on this 'til Im blue in the face and since I've become known for doing that . . . why the hell not.

12V is more than enough to kill you. I dont think that $20 makes me any safer.

The switches I'm using are UL approved. They are rated for 0.28 amps at 120V AC. I'm not sure what you know about UL but it only applies to certain uses of certain things, i.e. these switches are actually designed for use in HVAC Condensate systems so the UL approval will most likely only be valid in that application.

I would agree that in reality there is no amount of money worth my life however we take chances every day with a million little things, nothing is risk free. Just by getting out of bed I am risking death. Just because something is UL listed doesnt mean it wont fail, just because you've used less electricity doesnt mean it wont kill you. I'm confident that the system in my tank is as safe as I can make it within my own limits of risk. I'm confident that if something goes wrong with this system that there will be indicators to that failure that will be obvious to me before I put my hand in any current filled water that would kill me.

Now on to experience, I have had voltage in my system on two occasions. Once due to a 250W heater another due to a powerhead. In the case of the PH the current was directly in the main tank, there were no ill effects on my tank inhabitants only on me when I poked my hand in there. The heater was in the sump and I only found out about the problem when I stuck my hand in the sump to pull my return pump for maintenance. It had probably been that way for some time and I had my hands in the main tank prior to that and felt no stray voltage in the tank as a result.

So short of removing all the electrical devices from my system I cannot eliminate the hazard. Awareness is the key.

 

[Tstone]

Smiley face impression of Rob.

 

[Tstone]

Oh yeah I agree Rob.

I took a chance and got out of bed this morning and lived to tell about it.

 

[NateHanson]

I'm not trying to get into something here , but 12V actually can't even shock you, let alone kill you. The potential in 12 volts is barely high enough to overcome the resistance in your body, so 12 volts generally won't be able to shock you if you're holding pos and neg 12 volt leads in opposite hands. 120 V on the other hand has more than enough potential to travel through your body.

 

[RobboT]

I give up Heading out to connect my car battery to my testicles to prove Nate's theory

 

[smcnally]

I'm not trying to get into something here , but 12V actually can't even shock you, let alone kill you. The potential in 12 volts is barely high enough to overcome the resistance in your body, so 12 volts generally won't be able to shock you if you're holding pos and neg 12 volt leads in opposite hands. 120 V on the other hand has more than enough potential to travel through your body.

Not to dredge up an old thread, but I just read this and was wondering if this is what a lot of people think. 12Volts can kill you just as well as 1 Volt can kill you if it has the right amount of amperage. One thing I was taught in electrical training was this quote "It isn't voltage that kills you, but the amperage in it" Did you know that when you get a static shock on your finger tip when touching a door knob etc., that that is a minimum of 3,000 volts. Crazy, huh?