I bought two Ecobee Smart Thermostat Premium to replace our older Honeywell thermostats.

I checked both thermostats and their wiring matches and they do not have a C wire present. So I figured I’ll need to install the PEK to the HVAC control panel… …except, I go to the control panel inside and find that the control panel does have a C wire present.

I’m a bit confused since I don’t grasp why the control panel would have it when neither thermostats has it? Is there another panel somewhere I should be looking for like a zone panel?