Protection question - heating cables

[KellerAg]

Hello everyone,

I’ve read this forum for a long time but never posted.  
 

I’m in Keller, TX (8a I believe) and I wanted to ask if anyone had experience with the pipe heating cables available at Home Depot?  I wrapped all of my palms/cycads in burlap and then used the pipe heating cables, followed by landscape fabric and then a 9 mil tarp.  

The species are Mediterranean fans, butia capitata, cycas revoluta, cycas taitungensis, cycas panzhihuaensis and a hybrid tait x panzi.  
 

With the exception of yesterday afternoon for about 3-4 hours, the temp has been below freezing since Thursday which is when I did all of this prep.  The heating cables have been on the whole time.  Is there a chance that those cables got too hot?  I’ve never used them before but I reached up under the protection yesterday to feel the crown of the butia and the revoluta and I was quite surprised at how warm it was.  So now I’m worried about killing them by trying to protect them.  

Of course, it does give me hope that they may survive Mon/Tues/Wed (assuming I didn’t do too much heat damage).

Thanks