wiring float switches

[aquaman2]

A couple days ago I asked about wiring floatswitches. I got lots of good answers, but many were too complicated for me to understand. They involved wiring releys, and schematics I didn’t understand. Well I got my FS's from floatswitches.net. I always see people talk about these and recommend them, but have never seen anyone give this page from their site. It is awesome. I was nervous about not wiring the auto top off to a reley and having 120v in my system. Not anymore.

top off

[GMGQ]

Great overally DIY webpage.

HOWEVER, look at the white extension chord part. There's copper wire exposed?!! Then they tell you to heat shrink the whole thing together??? Those exposed strands of wire will definitely touch each other. Even though it's from the same wire, if the exposed parts touch, then the current wont go through the relay like it should.

You should clean up that exposed wire, maybe wrap each one in smaller heat shrink or electrical tape, THEN use the large heatshrink to wrap everything up.

[aquaman2]

THAT WIRE DOSENT MOVE ELECTRICITY. ITS INSULAATION I BELIVE

[Pyrojon]

That is a GFCI extension cord I believe. the braided insulation is a ground and probably needs to be intact for the GFCI to work properly. So you definatly want those exposed wires to touch. If not the GFCI may not work properly and you may as well use a regular $2 extension cord from WalMart.


My only criticism of the project is that the relay is powered by a 9v battery. This should be replaced with an AC Adapter and plugged into the wall. That 9v will run out faster then you think and the result will be that your autotopoff will stop working and your tank level will drop, which defeats the purpose of the whole thing in the first place.


btw, what's wrong with these switches switching 120v directly?
What's so scary about having a 120v device in the tank, don't your powerheads, heaters, etc... all run on 120v?

[aquaman2]

120 CAN FRY THE SWITCH

[Pyrojon]

From the floatswitches.net web site

- Max voltage/current:220VDC/1.5A

I have been using these exact same float switches, switching 120v, in my system for about a year. No fried switches yet.

[chrisguy]

Its a great DIY page. It's a nice simple design for someone that might not want/need a more complicated system.

[Bugs]

That is a straight forward steps-by-steps. Great design with one little draw back as Pyrojon described. Maybe aquaman2 can give us an update on how long the 9V battery would last with this setup...

[aquaman2]

actually, when i asked about the stuff the other day, the part that confused me was wiring the relay. now that i see how easy it is, ill probally just use the 12v *****. ill just follow the instructions and replace the 9v with the transformer.

[aquaman2]

*****. = transformer. dont know why its blocked t-r-a-n-s. is what i put in

[Johnnyfishkiller]

Originally posted by aquaman2
120 CAN FRY THE SWITCH

I agree with Pyrojon. IMO/E there is no reason to make it overly complicated. Just run 120 volts to a switch designed to do the job and be done with it. I run a solenoid valve on the output of my RO unit for my top off. It's been running over 2 years with no problems. My solenoid valve draws about 1/4 of the switch rating, so the possiblility of it burning up the switch is low, plus I run a backup switch just like the pictures showed. Besides, why would you think that 120 would cook a switch faster that 12v? Switches burn from too much current, not voltage. Higher voltage systems tend to run lower current to do the same job.

The wiring on my top off consists of a 99 cent extension cord, and enough 18/2 bell wire (@ .19 per foot) to get to my sump. Just wire the whole thing in series and you're done.

I also plugged the extension cord into a timer. It does two things for me. When the RO unit runs, it will run for longer periods and produces cleaner water than short bursts. Second, it limits the daily production of water. If something bad happens, it will be a 3 gallon bad day instead of a 100 gallon bad day.

[xrunner1234]

I'm disappointed that they did not show a suppression device such as a diode or a zener. It should be there to clamp the inductive voltage spike that the relay coil and the floatswitch will see when the relay is turned off. This will greatly increase the reliability of floatswitch.

[Johnnyfishkiller]

Originally posted by xrunner1234
I'm disappointed that they did not show a suppression device such as a diode or a zener. It should be there to clamp the inductive voltage spike that the relay coil and the floatswitch will see when the relay is turned off. This will greatly increase the reliability of floatswitch.

True. The voltage spike from a 12v relay can easily exceed 250 volts, well over the designed rating of the switch.

Another good reason to use AC. You don't have to learn which end is which on a diode, or figure out what a zener is.

[xrunner1234]

Originally posted by Johnnyfishkiller
Another good reason to use AC. You don't have to learn which end is which on a diode, or figure out what a zener is.

Simplicity is usually the best route. But since most DIY'rs do not know how to wire for safety and per UL, it is not advisable to wire the floats using household AC. There is a reason that UL charges so much for certification and performs many tests.

[chrisguy]

xrunner1234 - any chance you can provide a diagram of how the diode or zener would be wired and what the correct version would be? I would like to add one to my DIY auto top off.

Thanks!

[Blazer88]

I'm curious as well about the diode. I have most of the parts rounded up to build this thing and would like to add the diode. Thanks.

[xrunner1234]

Sure. Check out this thread http://archive.reefcentral.com/forum...hreadid=437217

I have a schematic there of my setup.
Also check out Tyco's write-up about coil suppression.
http://relays.tycoelectronics.com/app_pdfs/13c3311.pdf

[chrisguy]

Originally posted by xrunner1234
Sure. Check out this thread http://archive.reefcentral.com/forum...hreadid=437217

This link takes me to a list of all forums here on RC.

[xrunner1234]

Sorry. http://archive.reefcentral.com/forum...hreadid=437217