Identified Handle Ties for Circuit Breakers

[underQ]

I'm studying the National Electric Code book's material on :

Multiwire Branch Circuits ( Art 100 Def., 210.4, 240.15(B)(1) )
and
Multiple Branch Circuits ( 210.7,240.15(B)(2) )


Here's part of what I've dredged Up:

240.15 establishes the prelude to a Branch Circuit's Ungrounded Conductors:

(A) An Overcurrent Device is Required and it offers three options :
A fuse,
A Circuit Breaker having an Overcurrent trip unit,
A CT w/ OC relay


Then this section focuses on the Circuit Breaker with overcurrent trip unit option :

(B) Circuit Breaker as Overcurrent Device
It must be capable of opening all ungrounded conductors of Branch Ciruit AUTOMATICALLY AND MANUALLY

(and then it goes on to provide what I consider exceptions)

unless otherwise permitted

(which it then gives 3):

(1) 240.14(B)(1) Multiwire Branch Circuit --ok to use "identified handle tie)
(2) 240.15(B)(2) Grounded Single-Phase A/C Circuits ==> Line-to-Line 1-phase circuits
(3) 240.15(B)(3) 3-phase...

Now here is my Question: From this reading, I get the idea that an "identified" handle tie only provides manual opening of the ciruit breaker.
I've seen single-pole breakers (two) tied with a handle tie in a tripped condition with only one (of the two)
breakers tripped.
I've never paid attention to 3 breakers tied..., and I was wondering what would happen if a three-tied breaker
arrangement had an overcurrent condition... on the center breaker so that automatic tripping would happen on
only the middle breaker?

So, now my one question has become two questions:
1. Does an identified handle tie only provide manual disconnect for the circuit breakers that are established to protect the ungrounded conductors,

and

2. Would the center breaker trip if an identified handle tie arrangement were used on a Multiwire or Multiple Branch Circuits that has a fault on the center breaker?

What I understand from my reading is that either type (Multiwire B.C. or Multiple B.C.) requires there to be more than one ungrounded conductor..., that the Multiwire requires there to be a grounded conductor (Multple B.C. doesn't mention the grounded conductor so it either has no neutral, more than one neutral, or there is either no voltage difference between the ungrounded conductors... or there is a different level of voltage between the two or more ungrounded conductors and this neutral... to make the the Multiple Branch Circuit distinct from a "Multiwire" Branch Circuit.

I'm probably overthinking all this..., but it has been a difficult concept for me to get a clear 'handle' on..., and "handle ties" have been a relatively obscure subject for me... which I am working to resolve.

Richard Blankenship

 

[WoodrowJWeen]

I've actually asked several circuit breaker manufactures if handle ties will ensure automatic tripping of the connected poles. They all agreed...maybe. So essentially handle ties are good for multiple single phase (phase to neutral)circuits sharing a neutral but not three phase loads.

 

[dpc]

For what it's worth, we never allow use of handle ties - only multi-pole breakers.