While installing a new thermostat I accidentally attached the blue wire (common) to the heat damper terminal on the thermostat. It is a common 5 wire set-up with red being hot, white being the heat relay, the yellow being compressor contact and the green being the fan. I lost power to the thermostat. I checked my breaker box and all was OK there. What I want to know is if there is a fuse for the red wire or did I do some damage. The thermostat is a Honeywell T8600D
Thanks
Randy

What you are looking for is a small fuse for the 24 volt control circuit, which may be at or on the control transformer, or mounted on a control board at the furnace/air handler.

If there is no fuse, need to check the 24 volt output of the control transformer, may have caused this to fail by shorting out the control circuit.