Pitot Heat ground

[rvg8tor]

Interesting thing while testing my pitot heat.  I hooked up black to ground of my power supply, red to positive and light to white and all worked well.  I then decided to test the ground to the airframe since I am pondering whether to run a ground line to the pitot controller or locally grounding to the airframe (metal plane), the battery ground will be attached to the airframe.  Well I had not yet connected the controller black wire to the airframe and I hear the pitot controller kick on, hmmm.  It seems the controller box which is attached to a wing rib is making a ground.  Should this be happening or do I have something wrong inside the controller box?  

Thanks for any help. :-/

 

[dynonsupport]

The controller box is grounded to the circuit internally, so if it's hooked to a metal airplane, it will operate.

It wasn't designed to use just this ground, so while it won't hurt anything in the short term, you do need to hook the ground wire up as well, even if it is just to local grounding spot.