[utchuckd]

Do things that have their own switch (or don't need a switch) have to go through a circuit breaker or fuse/switch? I want to add a 12v outlet and stereo on my boat. Does the outlet need to be able to be powered off? Does the stereo need to be on the panel since it has it's own power button?

I've got one open spot on the original panel and could run one of them through it, but I could also put in a small fuse block and bypass the switch panel. I'd like to keep the current panel for now as it's the original to the boat, plus a small fuse block is much cheaper than replacing the whole panel. If I added anything in the future is when I would look at replacing the panel.

 

[eherlihy]

I believe that you are asking if everything needs to be on its own individual breaker. The answer to this is NO. I have frequently advised my customers to combine several circuits onto a single breaker, with a distribution fuse panel closer to the components.

For example; on my boat I have a fixed VHF, a 12VDC outlet, and chart plotter, all mounted at the navigation station. I am also preparing to mount an AIS class B transponder. All of these devices are (or will) be connected to a 6 circuit fuse panel at the Nav. station. This panel is connected to a single 15A breaker on the main distribution panel, with 10 gauge wire, and labeled "Nav. Station".

Another common upgrade that I have made is to wire the running lights, steaming, foredeck, and anchor lights to a sub breaker panel near the helm. These are then run to a single breaker at the distribution panel labeled "Nav. Lights".

 

[fryewe]

Run a fused 12V receptacle off the panel switch if you like. The stereo is both fused and switched, most likely.

An issue such an installation is that the programmer/clock in the stereo (which draws minuscule power) may need continuous power, and when you unplug the stereo from the receptacle, or turn off the main power switch, you may lose all programmed channels as well as interrupt power to the clock, requiring resetting the clock.

 

[utchuckd]

No, I'm asking if a 12v outlet and/or radio needs to be on a switch (breaker or fuse/toggle switch) at all. I do like the sub-panel idea.

Maybe I'll just go ahead and change it all out, its 35 years old anyways.

 

[ccriders]

The 12V outlet needs to be on a breaker as you do not know what will be plugged into it, just like in your house. The stereo (AM/FM radio?) can share a breaker with other like devices with a total amp draw less than the breaker capacity. But do it right and don't load up a terminal strip with several wires on one screw post, and use a jumper bar to connect several circuits together.
Also, from my experience, if you decide to rewire, then take out all of the old stuff and redo it with all new breaker panel, wires, outlets, etc. it will be much easier than trying to work with who knows what has been done in the last three plus decades.
At least that has been my experience. Especially mast wiring. If I were doing it again, I would not use a mast head anchor light, but one that can be hung on the forestry and hoisted as needed.
John

 

[btrayfors]

No, it doesn't have to be on a switch, though that is often convenient.

However, it does have to be on a fuse or breaker, preferably 15A.

Piggybacking on other circuits with their own 15A maximum CPD (switch or breaker) is OK, as indicated above.

Bill

 

[eherlihy]

The fuse/breaker is there to protect the wire. This is to prevent a fire. EVERY length of wire should be protected by a fuse/breaker within 7" of the source.

There is no requirement to add another switch.

 

[utchuckd]

Thanks everybody.

 

[MarkSF]

So, you can share a breaker that's already in use, provided that you don't mind that everything on that breaker gets switched on and off together!

A good solution to running several devices off one breaker is a DC sub panel like this :

Amazon.com: Blue Sea Systems 5025 ST Blade Fuse Block - 6 Circuits with Negative Bus and Cover: Sports & [email protected]@[email protected]@http://ecx.images-amazon.com/images/I/51%[email protected]@[email protected]@51%2B5nXsWtYL

For example, my "instruments" breaker powers up one of these fuse blocks. The instruments connect to this block. Keeps the wiring nice and tidy.

 

[PitApe]

While every single item doesn't need its own fuse/breaker, everything should have some sort of circuit protection. Bundling all the interior lights makes sense, for example (although, wiring the Prt and stb lights separately is even better). However, a fault in one item could trip the breaker (or blow the fuse) and then the interior is in complete darkness. Likewise, if you bundle all your boat's electronics together and have just one breaker/fuse for the lot you risk a fault in one causing all of them to be useless.

I would put something like a 12V plug on its own breaker/fuse for the simple reason that you are more likely or have problems with that circuit as you plug in different gizmos, each of which might have been rattling around in a locker for who knows how long before you decide to use it that day. That way when your 12V blender blows the fuse as you are making Margaritas you can at least have your interior lighting on while you search through the boat for a replacement fuse.

I am in the process of redoing the 12V system on my boat. I'm wiring the Port and Starboard interior lights, and each of the 12V plugs, so that they are on their own circuits. I'm also wiring two separate 12V plugs in the cockpit (for use with the tiller pilot, spotlight, and a hanging lamp I sometimes use while eating/entertaining in the cockpit). That way, if one circuit blows I have a backup and/or can more easily trace the problem.

 

[utchuckd]

The more I look at it the more I know need to redo everything, I just didn't want to get into that yet.

How many of y'all run a radio through a fuse only so you don't lose the clock/station memory programming?

 

[ccriders]

The more I look at it the more I know need to redo everything, I just didn't want to get into that yet.

How many of y'all run a radio through a fuse only so you don't lose the clock/station memory programming?

I only listen to one station, so don't worry about it. Plus there are clocks all over the place.
John

 

[MarkSF]

They usually have a memory backup wire, and a main supply, so run the backup via a fuse and the main via the breaker.

 

[Minnewaska]

I've had to do too much troubleshooting over the years to want different wiring systems on the same boat, ie. some through the panel, some not. Headache. A direct wired bilge pump for safety may be the only exception, although, that also runs through a dedicated breaker on the panel on my boat. Makes it easier to power down, so I can clean the filter.

 

[eherlihy]

The more I look at it the more I know need to redo everything, I just didn't want to get into that yet.

How many of y'all run a radio through a fuse only so you don't lose the clock/station memory programming?

The radio will have a "DC +" wire, which will be red, and have a 2-5A fuse, and a "memory" wire, which will be yellow, and should also have a 0.5A fuse.

I said this before, but it bears repeating; all "+" wires should be protected by a fuse/breaker within 7" of the power source.

 

[ccriders]

Which would be the positive terminal strip for the DC+ wire and the battery for the "memory" wire?
John

 

[eherlihy]

Which would be the positive terminal strip for the DC+ wire and the battery for the "memory" wire?
John

Yes