thermostat sensor placement

Where is the best place for the thermostat sensor to be placed? I have paper towel substrate over top of reptile carpeting. Should it be touching the bottom or off the floor a little?
I have it toward the middle of the hot side (away from the glass) propped up about half an inch off the bottom. It is set to 92.

I have a tub set up, but the basics should be the same, my probe is under the tub touching the heat pad. If its inside the tub the snake can move it around.

I place my T-Stat sensors on the outside of my enclosures foil taped to the UTH or Heat tape. You should not place them in the enclosure in case the snake urinates or spills water on the probe which would drop the reading on the probe causing the temp to spike and possibly burning the snake. Hope this helps :P

Yeah, I agree with the above posters. You don't want the probe inside the tub at all. Always on the heat source.

Cheers.

I already knew this, but can someone post a pic of how they tape it so I can get a visual?

I use both interior and exterior placements. Interior provides much more accurate temps I use hot melt glue to secure the probe. With exterior ambient air temps effect the temp quite dramatically especially if they vary a lot. I know Dion of herpstat does not recommend foil tape or exterior mounting, the claim with foil is the ambient air temp has a even greater effect on the accuracy.

The 'issue' of spillage on the probe in my tests the snake waste is in the mid 80s temp wise and the spike is only about 2-3 degrees and if set point is 90 a maxed out temp of 92-3 and only for about ten min. I have had a large water bowl spilled on the probe, the 'spike' was not so much a spike but a drop of 5 degrees and then the area returned to normal hot side temps. Local spill is not large enough to effect much and large ones drop the whole hot area and it returns at the same time.

In either set up the probe MUST never move the snake must not be able to nor can the cat, door ect. It must be firmly fixed in place. I always recommend a failsafe T-Stat in cse the probe is pulled in any set up.