I recently ran into a problem on my O'Day 34 with Universal 25 diesel. Engine refused to start with no power to engine panel. Problem was traced (after an hour) to a faulty 20 Amp fuse behind the panel. The fuse did not blow, it merely decided to fail internally after 20 years in place (no corrosion present). This fuse is shown on the Universal circuit diagram as protecting the key switch and I assume the starter solonoid and was mounted in a fuse holder that required removal of the contents of the cockpit locker and a back panel behind the engine panel to access it. My questions: What is this fuse protecting? Is it needed? Wouldn't a circuit breaker at a convenient location be better or could I just elimiate it? Boat runs fine with new fuse and fuse holder wired in place but this bothers me. Thanks for comments.
fuses on starting circuits
- Thread starter wayneR
- Start date
- Status
Tinned wire .....
If the boat is over 20 years of age then probably there is corrosion within the strands of wire, especially in the 'connections'. Such corrosion results in high resistance which results in heating the connections. If you have a 'fuse problem' in the starting circuit .... its time to replace the wiring/fuse holder/switches, etc. with pre-tinned *marine grade* wire, etc. Most boat builders use non-tinned 'automotive' wire ... cheap stuff that corrodes easily in the marine environment. The fuse protects the whole starting circuit including the 'primary' side of the starter solenoid - but not the full power (secondary - BIG WIRE from the battery to the starter).
If the boat is over 20 years of age then probably there is corrosion within the strands of wire, especially in the 'connections'. Such corrosion results in high resistance which results in heating the connections. If you have a 'fuse problem' in the starting circuit .... its time to replace the wiring/fuse holder/switches, etc. with pre-tinned *marine grade* wire, etc. Most boat builders use non-tinned 'automotive' wire ... cheap stuff that corrodes easily in the marine environment. The fuse protects the whole starting circuit including the 'primary' side of the starter solenoid - but not the full power (secondary - BIG WIRE from the battery to the starter).
Fuses
Wayne, The fuse is protecting your boat. Should the wiring downstream become short circuit the fuse should blow rather than making all the wiring upstream red hot. All wiring to a fuse must be capable of carrying the rated current of the fuse as well as all wiring from the fuse - until another fuse is reached (if there is one). Of course the wiring must also be capable of feeding the unit on the end without excessive voltage drop. For info fuses normally have a 1000 hour rating if run at full current.
Wayne, The fuse is protecting your boat. Should the wiring downstream become short circuit the fuse should blow rather than making all the wiring upstream red hot. All wiring to a fuse must be capable of carrying the rated current of the fuse as well as all wiring from the fuse - until another fuse is reached (if there is one). Of course the wiring must also be capable of feeding the unit on the end without excessive voltage drop. For info fuses normally have a 1000 hour rating if run at full current.
Fuse
Wayne, The fuse is protecting your boat. Should the wiring downstream become short circuit the fuse should blow rather than making all the wiring upstream to red hot. All wiring to a fuse must be capable of carrying the rated current of the fuse as well as all wiring from the fuse - until another fuse is reached (if there is one) For info fuses normally have a 1000 hour rating if run at full current.
Wayne, The fuse is protecting your boat. Should the wiring downstream become short circuit the fuse should blow rather than making all the wiring upstream to red hot. All wiring to a fuse must be capable of carrying the rated current of the fuse as well as all wiring from the fuse - until another fuse is reached (if there is one) For info fuses normally have a 1000 hour rating if run at full current.
fuse
if you don't mind spending the money a breaker is far greater then a fuse. put a 20amp breaker in place of the fuse and you'll be fine.
if you don't mind spending the money a breaker is far greater then a fuse. put a 20amp breaker in place of the fuse and you'll be fine.
Starting Circuits
Overcurrent Protection (fuses or cct. breakers) is NOT required on Stating Motor Circuits. The Ignition Switch is part of the starter circuit, so no fuse is required. The engine instruments are normally supplied from the ignition switch, and DO require fuses. As has been indicated, fuses protect the downstream wiring and ultimately the boat, so you may wish to protect the start (ignition) switch circuit with a high ampacity fuse (provides short circuit protection, but not overload protection).
Overcurrent Protection (fuses or cct. breakers) is NOT required on Stating Motor Circuits. The Ignition Switch is part of the starter circuit, so no fuse is required. The engine instruments are normally supplied from the ignition switch, and DO require fuses. As has been indicated, fuses protect the downstream wiring and ultimately the boat, so you may wish to protect the start (ignition) switch circuit with a high ampacity fuse (provides short circuit protection, but not overload protection).
Fises
Not much to add here, other than fuses need to be placed as close as possible to power sources. Fuses are critical. I would change the fuses from glass to ATC and have a Multimeter for testing. Best, Trevor
Not much to add here, other than fuses need to be placed as close as possible to power sources. Fuses are critical. I would change the fuses from glass to ATC and have a Multimeter for testing. Best, Trevor
- Status