Circuit Breaker and Fuse Characteristics
CHARACTERISTICS         CIRCUIT BREAKERS         FUSES
COST                                    Higher                            Generally low
Maximum Interrupt
Capacity Available                5,000A                               20,000A
Operate as Switch                  Yes                                     No
Re-settable                              Yes                                     No
Vapor Proof                           Some                                   No
Size Ranges Available        to 150 Amperes*            to 500 Amperes

*Until the 1997 introduction of Blue Sea Systems' 300 Ampere High-Load" Multiple Pole Circuit Breakers.

THERMAL Circuit Breakers versus Magnetic Circuit Breakers -how they work
Both thermal and magnetic circuit breakers must convert amperage to mechanical force in order to open the circuit.

Thermal Circuit Breakers use the amperage to heat an element which then deflects and opens the contacts.
Magnetic Circuit Breakers use the magnetic field created by the current in a coil to attract the armature and open the contacts.

Thermal advantages                         Magnetic advantages
   · Lower cost                       · Insensitive to ambient temperature
   · Greater size range            · Less variation unit to unit in opening
                                                   speed for a given amperage

========== ABYC standards
DC Circuit Breakers
E-9.11e. Circuit Breakers--Circuit Breakers shall:
   (1) Have a DC voltage rating of not less than the nominal system voltage:
   (2) Be of the trip-free type;
   (3) Be capable of an interrupting capacity according to Table II
        and remain operable after the fault. (integral over-current
        protection in electrical devices may have a lower interrupting
        capacity);
    NOTE: A fuse in series with, and ahead of, a circuit breaker may
          be required by the circuit breaker manufacturer to achieve
          the interrupting capacity.
   (4) Be of the manual reset type except as provided in ABYC E-9.1l.g; and

AC Circuit Breakers
E-8.11.3   The AC voltage rating of the over-current protection device
                 shall not be less than the nominal voltage of the supply circuit.
E-8.11.4.1 meet the requirements of Underwriters Laboratories, Inc.
                  UL 484, "Molded Case Circuit Protectors for Circuit Breaker   Enclosures". or UL1077, "Supplementary Protectors for Use
                   in Electrical Equipment", or UL 1133, "Boat Circuit Breakers",
                    and
E-8.11.4.2  be of the trip-free type, and
E-8.11.4.3  be capable of an interrupting capacity in accordance with
                    Table I, (see page 3 for Tables I and II referenced)