Moderated Discussion Areas
ContinuousWave: Small Boat Electrical
|Author||Topic: Fuse Location|
posted 08-27-2006 05:49 PM ET (US)
I am re-wiring the lights on my 25' Revenge. Does it matter whether I put the fuse before or after the on/off switch?
Also, all the lights currently have a common hot wire which is pig-tailed between each of the switches. I am inclined to install a bus bar and run separate hot leads to each switch. Thoughts?
Thanks for your responses in advance.
|Casco Bay Outrage||
posted 08-27-2006 07:24 PM ET (US)
Usually the fuse goes between the switch and the light.
While sharing a single power run, I prefer to have seperate feeds for individual switches. Note that Blue Seas, Marinco and other switch panel manufacturers often run a single power and then wire the switches in series. It important to have the appropriate gauge of wire if you do an in-series approach.
The switch panel I am referring to can be seen in my re-wiring project thread. Scroll down to the "console after photo".
Hope this helps.
posted 08-28-2006 08:36 AM ET (US)
As a general practice, I usually see over-current protection devices placed at the point of power distribution. This would put them before any switch.
In the case of very sensitive devices, it is often seen that a fuse is installed as close to the sensitive device as possible, usually inside the unit, on a rear panel, or in the unit's power cord.
|Casco Bay Outrage||
posted 08-28-2006 10:12 AM ET (US)
I defer to Jim on this. Sorry for the inaccurate information.
posted 08-29-2006 01:08 AM ET (US)
Generally the current protection device should be close to the distribution center. If the current protection were farther downstream, the wiring from the distribution center to the switch would not be protected. If a short occurred in the switch, the wiring could burn up without blowing the main fuse protecting the distribution buss.
For example, a typical set up is to have an 8-AWG conductor feeding the distribution center from the battery primary distribution. This circuit is protected by a 30-ampere circuit breaker.
If a 16-AWG wire runs from the distribution center to a switch, then to a fuse, and then to a small lighting circuit, this wire could carry a very high short circuit current if a fault develops ahead of the fuse. If 30-amperes of current flow in a 16-AWG wire, there will be a lot of heating. However, the main 35-ampere circuit breaker will not blow. This fault could create a hazard.
If the fuse is located at the distribution center, any fault in the 16-AWG wiring will be protected by the lower current fuse.
posted 09-01-2006 01:23 AM ET (US)
If the fuse is located at the distribution center is there a need for the 35 ampere circuit breaker?
Also, what do you think about the pigtailed hot wire connected to the navigation lights, compass, anchor light, spreader lights, and power port (cigarete lighter)?
Thanks for the great advice.
posted 09-03-2006 08:58 AM ET (US)
I think it is best to have a distribution panel, such as a Blue Seas fuse block, and fuse the nav lights seperatly. Plugging in a defective spot light at night could knock out your navigation lighting at a bad time. I'm planning on redoing my wiring this winter and will be relocting the fuse panel out of the area it is in to make it more accesable. I also prefer fuses over circuit breakers as they involve basically a simple heat related reaction, while a circuit breaker has mechcanical parts to also contend with................Jack (87 Revenge)
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