Quote:
Originally Posted by FF
Most boats with a 30A power cord are wired so if the total on board load goes over 30A a breaker on the boat will pop.
Your power cord is protected because your boat is limited in its load.
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This thread has kind of gone full circle. What FF is saying is true. Most boats have an onboard breaker and those that do not should because it is an electrical requirement.
NFPA 302
9.9.2* Overcurrent Protection Location. Conductors other
than cranking motor conductors shall be provided with overcurrent
protection at the source of power unless permitted by
9.9.2.1, 9.9.2.2, or 9.9.2.3.
9.9.2.1 Where not practical to locate overcurrent protection at
the source of power, conductors other than cranking motor conductors
shall be provided with overcurrent protection no more
than 7 in. (18 cm) from the point at which the conductor is connected
to the source of power measured along the conductor.
9.9.2.2 If the conductor is contained in a sheath or enclosure,
such as a junction box, control box, or enclosed panel,
throughout the required distance, and where not practical to
locate overcurrent protection at the source of power, conductors
other than cranking motor conductors shall be provided
with overcurrent protection no more than 40 in. (102 cm)
from the point at which the conductor is connected to the
source of power.
With an onboard breaker, the argument that the 50 amp shore breaker does not protect the 30 amp shore cable is almost mute. To make it more insignificant,.... look at the electrical standard. All 30 amp shore power cords using #10 wire with 140 degree F insulation is good for 40 amps. With 176 degree F insulation and #10 wires it is good for 50 amps. Outdoors in open air anybody that questions the ability of a 10 gauge 30 amp shore cable carrying up to 50 amps is blowing air in a paper bag.
NFPA 302
Table 10.13.6(a) Ampacities of Insulated Conductors
Temperature rating of insulation
AWG 140F 167F 176F 194F 221F
10 ...40A .. 40A.. 50A . 55A . 60A