When i start to build my tortoise table where should i put the heat pad. I want to know because i am scared if the wood cathches on fire so is their a certain thing i can do for the heat pad.
Usually a heat pad is only used to warm up substrate to add more humidity. Are you wanting this to keep the tortoise warm? If so, I would suggest a CHE (ceramic heat emitter) which can used 24/7 (if needed) or in combination with a UVB light during the day and the CHE when lights are off. This way the heat comes from above (which is the best) and can directed into a certain or more limited space, which allows for cooler areas on the table.
I'm not a fan of using a heat pad for an indoor tort table. Some members have had good luck using heat ropes, but I've never tried that. Like Jacqui has suggested, using a CHE (ceramic heat emitter) to heat an indoor tortoise works better than a heat pad. You would use the CHE at night and a light for during the day. I like to use the MVB (Mercury Vapor Bulb) because it is heat and UVB all in the same fixture.
And just a note...most heat pads don't get hotter than 80F degrees, so catching your wood on fire probably won't be a problem.