Dimmer switches shutting off??????please help

bidden · 08-27-04, 08:05 AM

I have 4 individual cages, all with thier own wired flexwatt. I have double checked all the wireing to ensure it is correct.

The problem I am having is with the dimmer switches, they will just shut off with no reason. I have tried 2 different brands now, one from home depot and one from Rona, both just turn off with the knob still in the on position???? To reset them I just turn the dial to full for a couple seconds, then back to where it was, and then they come back on??

Anyone have any input on how I can avoid this??? or any brands that work properly??

Stockwell · 08-27-04, 08:45 AM

I have posted on this many times. Cheaper dimmers that use single time constant trigger cicuits will not restart after minor power blips. Even outages of less than one second will turn them off if they are being used much under half. The normal 6 buck dimmers are always a problem and require you to turn them up past half, then back down to get a lower setting.
The problem is any minor power interruption turns them off and if there is no human hand to crank them up to half , then down, they simply stay off.

You need to get your self one of the 15 to 20 dollar dimmers and look for ones that say "full range dimming" These are usually slider types.
This type utilizes a more sophisticated triggering circuit, and will come back on even at very low settings.
Another helpful thing is to put a small pilot light across your heat tape and the brilliance of the light will go up and down witht the dimmer setting and this will also give you a visual indication that your dimmer is still on.
If you go to Radio Shack or an electronic parts supplier, ask for a Neon pilot light rated for 120volts.. They come in a variety of sizes and colors. MAKE SURE it's for 120VAC, and wire it right across were the wires hook to the heat tape.

bidden · 08-27-04, 09:33 AM

Thanks a bunch Roy, definatly appreciate the help!!!

hooter · 08-29-04, 03:33 PM

wow why pay 15 to 20 dollar for a generic dimmer when you can get a rheostat for around $12...

Pretty much all rheostats have safty in mind considering they make them for animal use

Stockwell · 08-29-04, 04:32 PM

By definition a rheostat is a variable resistor.
They are not used at all in herpetoculture.
What you are buying for herps in any package are also simply "phase fired switches" known commonly as "dimmers", regardless of what you want to call them, or what they are labelled as. They operate by chopping off part of each cycle of line rather than by limiting current through resistance only as a true rheostat would do.
They may also suffer from the same problems as cheap dimmers depending on the type of firing circuit being employed.
It's easy to test for this common problem with them turning off with power blips..
Simply turn them down low, and unplug them, then plug them back in. Do this several times in a row, and see if they re-start every time, without you needing to first turn them back up, before down.
Also prices mentioned are Canadian dollars. Pet stores generally charge more than 12 bucks for dimmers packaged as herp heat controls

hooter · 08-29-04, 09:15 PM

Yes Stockwell,

I am aware that a dimmer is in fact a rheostat but at pet stores they have rheostats for reptile use thus they will not turn off after a certain amount of time.

As for price, Maybe in Canada rheostats are more than $12 but I can find them around here for around $10.

Whatever you buy I dont care but here in the states its cheaper to just buy the rheostat for reptile use and not have to worry about a dimmer failing because of the *wrong so to say* features.

BoidKeeper · 08-29-04, 10:42 PM

I have one from a pet store and it is not full rang. There is a narrow band that controls the light and then it is off. I buy the hardware ones and wire them to an extension cord and that way I can plug in up to 3 heat pads at a time.
Cheers,
Trevor