Actually NEC Article 430 states that you need both a branch circuit protector and a motor overload
And I could not find anything otherwise.
Branch circuit protection and motor overload are 2 completely different thing each is designed to do different things
Lets look at the overload
What is it for, to prevent the motor from drawing to much current ( Overloading) if the motor overloads the OL trips and if it’s wired correctly shuts off the motor. The overload can b in many forms the OL relay that is common, Manual starter overload combination that acts as both a starter and overload like the ones pictured here, they have morphed and changed over the years but basic concept is still the same. I have worked with most types including the old oil filled dashpots ( I dout anybody on this board have ever seen a dashpot OL)
NEC require some type of overload on all motor circuits except the small motors usually used in residential uses
In summary the overload is to disconnect the motor before it draws too much power and destroyers itself.
VFD’s have an electronic OL built in so and external one is not needed unless you are using the VFD to feed multiple motors then an OL is required for each motor.
Now lets look at the Branch Circuit Protectors
I have had the discussion may times before
I really think they should be called Branch Circuit Isolators because that what the do.
When they open they isolate the faulted branch from the main power source.
You must first understand there is no device available to disconnect any circuit before it faults ( Short circuit, ground fault whatever )
So the best you can do is to disconnect (Isolate) the branch as quickly as possible to protect the power source in a fault detection
With branch circuit protection you have 2 basic types the oldest and still the most reliable is the fuse then you have the modern CB circuit breaker I am not going to get into the different types they all work about the same different speeds , different current curves ect.
I have had panel shops tell me they don’t need a Branch Circuit Protector, their panels are to small to require one. What they forget is that when the panel is installed and powered from a plant main panel that main panel has a Branch Circuit Protector in it, the main panel breaker isolates the sub panel on a fault. So you actually have it anyway.
All circuits require a circuit protector from 5 V to 100KV transmission lines there is no exception to that.
A So if I have a client that insists that I don’t need either of them I walk away I don’t need that liability if something goes bad.
It always falls back to last person working on it.
To repeat both are required on all motor circuits.