smokeyangler:
When I had my fire I didn't have my fish finder plugged in. It was a Lowrance Elite 4 DSI fish finder. I did have my battery connected to the fish finder cord though.. My fire was due to a cigarette lighter extension receptacle that I had added to the wiring. It had gotten wet at ORC, dried and the corrosion from the salt water created a path for the electricity to flow. It created enough heat to start the wiring and socket to catch on fire. I will never go without a fuse again. I learned a valuable lesson.
Wilfite:
I know this is an old thread but since it is stickied I figured it would be worth updating.
I have a background in electronics and I have been doing marine wiring on and off for a lot of years. I see some controversy in this thread regarding fusing. The fuse is intended to protect your wiring, it is NOT intended to protect the load. The load (like a FF) will/should have its own fuse.
According to ABYC E-9.11.b "The rating of overcurrent protection devices used to protect a load other than a DC motor shall not exceed 150% of the current carrying capacity of it's supply conductor"
As I understand it, the 150% figure is to allow for short term current spikes (like from inrush current when you turn on a device) for a fully loaded wire circuit. Extended overcurrent situations will still blow the overcurrent device before the wiring is compromised. Best practice in normal situations where the circuit is not fully loaded is to rate the overcurrent device for the maximum of the wire or a bit below. According to the same ABYC spec, the maximum allowable current (under 50V) for common wires size is below. The two values are "outside engine spaces"/"inside engine spaces". I prefer to err on the side of caution and go for the lower value. 18: 10A/5.8A 16: 15A/8.7A 14: 20A/11.6A 12: 25A/14.5A
ABYC E-9.10 says Overcurrent Protection Device Location - Ungrounded conductors other than cranking motor conductors shall be provided with overcurrent protection within a distance of 7" of the point at which the conductor is connected to the source of power measured along the conductor. This means you need to place your fuse right at the battery rather than at the device.
You can certainly use a lower value fuse if you like, however as you go to lower values corrosion and mechanical stress will have a larger chance of damaging the fuse so it seems better to me to go for the largest hunk of metal fuse that is reasonable and still protect the boat.
Hope this helps folks in the future.
The spec is available here: https://law.resource.org/pub/us/cfr/ibr/001/abyc.E-09.1990.pdf
skidlybo:
Thanks for the reference. Brings back my old boat building days. It's worth the effort to research the correct way to wire/fuse something. It's so much easier to troubleshoot when something is wired properly.... and it won't catch on fire.