Need a little help in confirming my interpretation of 427 and specifically 427.22 from 2002 code. It appears that only electric heating systems that utilize heat trace or flexible heating panels require ground fault protection? Is this because they have no grounded external sheath as in earlier editions of the code?

Rusty,
The heat tape and heating panels must have a grounded conductive coating. Note that in previous codes, this covering was required to be metallic, but in the 2002 code it was changed to permit nonmetallic conductive coatins to be used. See 427.23. GFP was required even when the heat trace had a grounded metallic covering. The GFP is required because resistance heating can fail in a manner that will produce enough heat to start a fire without pulling enough current to open the overcurrent protective device.
Don

Thanks a lot Don,
I guess I just wondered what makes the heat tape different say from a hot water heater or the numerous other resistance heater apps that do not require GF protection.

Rusty,
I think that there is a lot more potential for damage to heat tracing than other types of resistance heating.
Don

I'll second Don on the damage issue.
When installed under pipe insulation, in order to help minimize potential damage, the outer sheath of the insulation should even have warning stickers(supplied from the manufacturer)to indicate that electric heat tracing is installed underneath.