Every problem cannot be solved with this checklist but it will give you a good starting place. Weve included copper wire specifications which comply with the awg standards at the bottom.
12 Way 32v Circuit Car Boat Blade Fuse Box Block Holder For
Fuse size for boat wiring. Study schematics never be afraid. 8awg is getting toward over kill in most. The continuous loads add up to 105 amps. This simple equation allows you to calculate the voltage drop for a circuit of any length and any current flow if you know the resistance of the wire. Of particular interest is the equation. For example a trolling motor on a 20 foot boat should have 4 or 6 gauge wire for best battery utilization.
Check the manufacturers installation instructions for recommended fuse sizes for each piece of equipment. Even a small boat 3 5 loads wed recommend at least 12awg wire for this. The fuse in a dc circuit should be about 150 of the load so a 15 amp would be appropriate. A fuse or circuit breaker is sized to protect the smallest wire in its circuit. This is sometimes a long wiring run on a boat. Blue sea systems dc circuit wizard performs calculations and recommends appropriate circuit protection optionsfuse or circuit breakerand wire size for just about all dc applications.
The current carrying capability ampacity of this wire is determined by referring to table 3 and then a fuse or circuit breaker is chosen with a rating no higher than this it can be lower. The fuses for each circuit should be 3 amp except for the radio because on transmit it draws 6 amps. Finally note that the amp capacity ampacity of the wire curtails. 10awg for larger boats 5 10 loads is normal. Plus these two conductors will carry the current of all your electrical loads combined so they are typically fairly beefy cables. Things could get really ugly really quickly so to avoid all that mess youll need to ensure that you get the right size fuse for the job every time.
If the circuit is properly placed in the fuse then the fuse will rise in the current. For your fuse to do its job correctly and protect your wires it should be rated about 11 to 15 times the rated. Load requirement and distance from the battery will help determine proper gauge wire and fuse requirements. So use a 10 amp fuse for the radio circuit. Essentially as complicated as things may look on your boat there are only two circuit designs that typically get employed. The wire size listed in the graph at the intersection denotes the gauge of wire to use.
Therefore each fuse has a rated size when the current exceeds the rated size when the fuse will be blown. Voltage drop current x length x ohms per foot. Remember this fuse is to protect the wire to the equipment. The main function of a fuse is to protect your wiring but in order to do so youll have to get the right fuse wire size from the start too low and itll blow too high and youll end up doing damage to the whole circuit. A change in six gauge numbers is a fourfold increase in wire size. Basic circuit design now that you know who the key players in this game are lets take a look at how we can keep them from ever becoming visible to the naked eye.
If there is not an exact match between cable ampacity and available fuse or circuit breaker ratings an overcurrent device with a rating of up to 150 of the ampacity of the cable can be used but thats the limit. For example we can determine the rating for a fuse or circuit breaker and we can select the proper wire size to supply a device without inadvertently holding back any of the amperage the device needs. When the wire size goes down two numbers from 14 to 12 the amount of. We need to determine the size of the main fuse. Fuses protect the electronic equipment from overcurrent damage but also to avoid electronic equipment due to internal failure caused by serious injury.
Gallery of Fuse Size For Boat Wiring
