Voltage drop length for Heat tracing pipe circuits

[rayp1]

The NEC mentions that the voltage drop is from the service equipment to the utilization equipment.

Heat tracing branch circuit is from the circuit breaker in the panel to the power box. Than the "consumer" or utilization equipment starts after the power box with heat tracing "heater cable".

The length we are using to determine the branch circuit voltage drop is from the breaker to the power box, not the heat tracing wire itself. Is this correct?

 

[rcwilson]

Correct. Calculate the voltage at the connection to the heat trace circuit cable. Do not include voltage drop in the heat trace cable itself.

However, voltage drop along the heat trace cable can affect its heat output. Follow the manufacturer's recommendations for maximum length of a circuit. The length also affects the inrush current when a cold circuit is powered up. If it is a self limiting cable that changes resistance with temperature it will draw a lot more current when cold, then reduce current draw as it heats up.