Reverse feed breakers - UL Listing

[Charz]

Why does the UL certification to be removed for the breaker, if the power supply is applied at LOAD and load at the LINE end of the MCCB?

I suppose there is no technical issue and we just need to ask the manufacturer to put the markings as below.

What do you think?

From UL 508A:

From UL 845:

 

[GoldDigger]

I don't know about the UL listing, but the NEC does not allow such use of a breaker with marked LINE and LOAD terminals.
There are some types of breakers which will not operate properly with the LOAD terminals constantly energized and the LINE terminals switched. These include any GFCI or AFCI breaker which powers the internal electronics from the LINE terminals as well as (possibly) shunt trip breakers.
For AC, unlike DC, the load breaking capability of the contact mechanism is unlikely to depend on the direction of energy flow.

 

[jim dungar]

I suppose there is no technical issue and we just need to ask the manufacturer to put the markings as below.

What do you think?

The information, you quoted, needs to be provided by the assembler of the control panel, not by the manufacturer of the circuit breaker.
The required labeling is telling people what to expect when they open the enclosure and are exposed to live parts.

UL489 applies to the breaker, as far as LINE and LOAD markings.

 

[kwired]

Breakers are not normally marked Line and Load unless their operation depends on it being a a certain way.

Standard thermal-mag or instananeous trip usually won't matter which way they are connected overcurrent detection concepts of those are only driven by the current.

A breaker that has powered electronics within will usually need the supply side connected to the "Line" terminals so those electronics are powered correctly.

 

[petersonra]

IME, MCCB that have removable trip units are labeled line and load and are thus cannot be reverse fed.

As best I can tell they make them non-removable by putting a piece of tape of the trip unit.

I think all the MCCB with electronic trip can be reverse fed though.