Circuit Breaker & Switch Panel Questions

[linesider2]

I've got some questions about the wiring for my boat. When I decided to start the mod I bought a 6 switch and circuit breaker panel. I'll attach a photo. A year or so later I'm now starting to really think of placement of everything and what I need to wire everything correctly. The packaging shows the total circuit capacity is 35 amps and 7 individually. I'm trying to read more about it and I understand quite a bit of it but still have questions.

Question 1: I've got a rule bildge pump that shows it is rated for 2.5 amps. With the correct wire size in proportion of length of wire used can I safely connect the pump to a 7 amp circuit breaker. I think the lenght of wire used will be about 7'.

Question 2: How about the nav light and anchor light. I want them on separate circuits and since they pull less than 1 amp is the 7 amp too much as well.

Question 3: Really the same question as 1 and 2 but for the depth finder. I know this doesn't use much power either.

Question 4: Should I or will I need to go with fuses instead because I can't find a circuit panel with anything like 3 to 5 amp individual circuit breakers.

I'm thinking that I bought the wrong panel for my needs. Can anyone give me some advice and opinions.

Thanks!

 

[seabob4]

Re: Circuit Breaker & Switch Panel Questions

You need to install breakers that are rated to protect your appliances. If the bilge pump is rated at 2.5A, you need a 3A breaker. Nav/Anchor lights are typically 5A. Depth finder? 5A. Any high power lighting, like spreaders? 10A. Just replace the breakers. Here, check out Defender Marine. Dirt cheap, and they will meet your requirements...

BTW, linesider...Snook?

 

[RicMic]

Re: Circuit Breaker & Switch Panel Questions

Circuit breakers and fuses are sized to protect the WIRE, not the device. You
size the wire to be big enough for the amp draw of the circuit and the length of the run and then size the fuse or circuit breaker to keep the wire from overloading. With a seven amp circuit breaker you could use #16 marine grade with and be find with any of that stuff.

 

[linesider2]

Re: Circuit Breaker & Switch Panel Questions

Thanks Seabob4 and RicMic. Seabob4, it's striper.

I've seen the debate on other threads as to what the fuse/cb is protecting, the wire or the load.

What I can't figure out is why they make these cb or fuse switch panel combos w/ a relatively large individual amp size for each switch if the typical loads we use and their recommended cb/fuse sizes are way below what is being sold in these panels. I hope this makes sense. I can try to explain better if it doesn't. There are so many people buying (including me) and installing these pre-made combo panels and I can't figure out why if they are unsafe.

 

[linesider2]

Re: Circuit Breaker & Switch Panel Questions

I guess it might have to do with the wire size after all?

 

[RicMic]

Re: Circuit Breaker & Switch Panel Questions

Its the wire, People assume that the fuse/cb MUST be there to protect the load, but its not, how would it? Devices that need a fuse to protect their internal wiring, such as a radio, have fuses built in. I was a working electrical engineer and designer for many years, take my word for it. The smallest normal wiring in a boat is #18 and a 7 amp circuit breaker is appropriate for that, hence the panel you have.

 

[NYBo]

Re: Circuit Breaker & Switch Panel Questions

Think about your house wiring. You can safely plug a 4 watt night light into a 20A, 12 gauge circuit although it only draws a fraction of an amp, right? The circuit breaker is to protect the wiring in case of a dead short so you don't have a fire. The night light is on its own. Same exact principle in your boat.

 

[linesider2]

Re: Circuit Breaker & Switch Panel Questions

Thanks RicMic and NYBo. I'm going to go with the panel I have and get to work. I'll try to update some pics of my wiring in progress and I'm sure I'll have some more questions.