Power Distribution and Control; Over-current Protection: Fuse v. Circuit Breaker

[Spc337]

As I rebuild my console I'm replacing the existing switches and probably going with [Blue Sea Systems] Contura Breaker Switches [see follow-up comment below]. I'm trying to avoid over engineering as I'm apt to do and getting a good lesson in ABYC standards from previous posts.

What would be helpful is to get some thoughts on what should be run through a circuit breaker and what is best left on a fuse circuit, such as on a fused circuit in a [Blue Sea Systems] 5026 distribution panel.

I have the following [circuits] which I will put on the [circuit breaker and control switch] panel:

• Nav/Anchor Lights (On/Off/On Switch)
• Deck Lights (On/Off Switch)
• Instrument Lights (On/Off Switch)
• FWD Bilge (On/Off) - This will be in the fish box in front of the console so I don't have to pull the plug to drain.
• AFT Bilge (On/Off/Auto) - Stern Fish Box
• MID Bilge (On/Off) - This will be a remote pump to aid in draining and water in the fuel compartment.
• Entertainment Audio (On/Off Switch)

Here is the list of additional [circuits] that will need power, but I'm unsure if there is any advantage to run from a [circuit breaker and switch] or to run from a fused circuit:

• VHF w/AIS (Fuse Block)
• Chart Plotter and Fishfinder (Fuse Block)
• Port Downrigger (Fuse Block)
• Starboard Downrigger (Fuse Block)
• USB Charger (Breaker Panel)

The VHF radio and the Chart Plotter have their own power switches. From what I understand it isn't healthy to simply cut power to these without properly shutting down. So I'm thinking Fuse Block.

Downriggers will be wired to the fuse block given the high current drawn.

The USB charger will likely be within the switch panel but not [controlled with a switch].

[jimh]

At first glance, I would configure the downrigger motors to have a circuit breaker instead of a fuse. If an electric motor stalls, it will draw a momentary high current. That momentary high current might cause a fuse to blow, but a circuit breaker may tolerate a momentary overload without tripping open. Even if the circuit breaker trips open, you can just reset it, but a fuse that opens will mean you will have to replace the fuse.

Update: for the downrigger motors, you don't need to take up a slot on the CONTURA switch and circuit breaker panel. I'd just use a separate circuit breaker for those loads. Since you won't be controlling the motors with the circuit breaker, it does not have to be mounted at the helm dashboard panel.

[jimh]

I was confused by your description of "Contura Breaker Switches."

I think you plan to use a combination of a push-button reset circuit breaker for circuit over-current protection and a regular ON-OFF switch for circuit control. These are actually two separate components. Blue Sea Systems combines the circuit breaker and the CONTURA switch on a pre-assembled panel for easier mounting.

For an example, of what I think you are planning, see

https://www.bluesea.com/products/8371/Water_Resistant_Circuit_Breaker_Panel_8_Position-Black

and

https://dh778tpvmt77t.cloudfront.net/images/products/8371.jpg

[jimh]

Re power to devices that have their own integral ON-OFF controls: I don't see any advantage to having a switch that controls power to a device that also has its own power switch. And, as you mention, modern marine electronic devices like a chart plotter should be powered off using their shutdown procedure. To simply cut off power to them might be harmful or at the least cause some data loss.

Also, many electronic devices today do not use a mechanical power switch. Even if you left the device in the "on" state and cut the power, you would most likely have to push the device's ON button to cause it to turn on again after you restored power. This reduces the convenience of controlling their power with an external switch.

[Spc337]

For an example, of what I think you are planning, see

https://www.bluesea.com/products/8371/Water_Resistant_Circuit_Breaker_Panel_8_Position-Black

Correct - Sorry for my short hand.

When I look at the images, many switches are labelled with "VHF" or "Chartplotter." I can't see the value in switching them in addition to their integral on-off buttons so thought I seek to understand. I'll wire them to the Fuse Block.

Thanks

[jimh]

The VHF Marine Band radio will probably tolerate having its power cut-off without any harm. But, as I mentioned, it is very likely you will have to push the radio ON button to turn it back on when power is restored. If you have two controls for power, then you have to switch two controls to "on" to get the radio working. It just seems like twice as much work to me.

The wiring of the CONTURA switches can become a bit tricky. I think they incorporate an LED annunciator lamp to illuminate when the switch is in the ON position. That generally means you have to run a lamp ground circuit to the switch.

For the control of the sump or bilge pumps, do you want the ON position to be normal or just momentary?

[Spc337]

Sounds like I'm on the right path with regard to what benefits from a switch and what will not. I'm going to investigate a breaker for the downriggers, the [Blue Sea Systems] version looks to run $90 per breaker which is very expensive.

$90 Breaker - https://www.bluesea.com/products/7136/1 ... _Mount_30A
or
$55 Breaker - https://www.bluesea.com/products/7181/2 ... _Mount_30A

I'm not sure what the difference is as the specs look similar.

Are there other breaker options that you would recommend?

Thanks
Sean

[NOTA BENE: there is no company called "blue seas"; the company is called Blue Sea Systems. No "s" on "Sea."--jimh

[jimh]

...I'm not sure what the difference is...

The more expensive device is designed to be used as a control switch and a circuit breaker in one device; it will tolerate many, many manual operations of the control from OFF to ON or back to OFF. Circuit breakers are NOT designed to be switched ON and OFF repeatedly. Often a circuit breaker will have a rather small amount of trip-OFF operations permitted, perhaps less than 100 trip-off events, either automatic or manual. You do not want to use a circuit breaker-only design as a control switch.

Are there other breaker options that you would recommend?

I bought an almost identical circuit breaker for about 40-percent less because it was not being sold as a marine product. In an earlier article I wrote:

I also ordered a 50-Ampere circuit breaker, also through Amazon, for $24. I ordered a Cooper-Bussmann model 185. I believe it is identical to the Blue Sea System type 185 (which is no longer offered by Blue Sea Systems). There is now very similar model offered from Blue Sea Systems, the 285, but the only difference I could find was the large stud connectors changed to M6 metric threads from 1/4-inch threads. The Blue Sea Systems breaker was $40. I could not see paying $16 more to get metric threads.

http://www.amazon.com/gp/product/B0024JHQ02/ref=oh_details_o01_s00_i00

[Spc337]

Thanks! That’s great info.