Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 21-06-2023, 05:15   #1
Registered User

Join Date: Aug 2009
Location: Lake Macquarie NSW
Boat: Chamberlin 11.6 catamaran
Posts: 991
Dumb questions about breakers

I am planning a total rewire of my cat. I have had some good input from forum members, thanks.

I was trying to get the price down of a build your own switch panel. I considered DIN rails but they don't seem to be easy to switch. I could use them as breakers only but I am more likely to use ATO car type fuses that fit in Blue Seas fuse blocks.

The hydraulic magnetic breakers used in most Blue Seas systems are pretty pricey. I can find thermal Carling breakers that are much cheaper and could use them as switches. But I have problems getting them in the correct current rating. 10 or 15 amps is easy, but what about 7 or 3?

When I look at pre-made panels, they seem like they have either 10 or 15 amp breakers. So if this is the case, and if I want to fuse the system for the appliance (most of my circuits are single loads apart from lights) I need a fuse block. (Appliance rated lower than wire)

So are the very expensive Blue Seas panels useful? It doesn't seem as though I can buy them without 15 amp breakers, so what is the point of having breakers if they are not specced for the wire or the appliance? It seems a heap of money to use a breaker (that may be too large) as a switch. In Australia, each hydraulic/magnetic breaker is about $30 and with about 25 switches on my boat, the panels are getting really pricey.

I am thinking I should just go toggles and fuse everything. Then I know that the circuits have proper tripping, either for the wire or appliance. I can still have all the fuses in a couple of places and easily check them. But the pricey Blue Seas panels are really popular. What am I missing? It means more than a thousand dollars for me to go the big Blue Seas panel road and I would really like to save that money.

cheers

Phil
catsketcher is offline   Reply With Quote
Old 21-06-2023, 05:47   #2
Registered User

Join Date: Oct 2016
Location: Monroe, Ga
Boat: 1987 Sabre 42 C/B
Posts: 417
Images: 1
Re: Dumb questions about breakers

Couple of options. I just finished rewiring/putting a new panel in my boat.

Look at frontpanelexpress.com. You can design your panel and they will build it to you spec. Their software is pretty easy to learn and you can monitor the price to have it made as you build it.

I used a friends laser cutter to make my panel. We designed the panel, cut it out, drilled all the holes, and etched in the labels. I am sure you could find someone local with a laser cutting to go this route also.

I liked being able to design my panel to my specifications and not have to conform to a commercially designed panel. Lots of options. I hope you find one you are happy with. As you are finding out to properly rewire your boat is going to be expensive. All of the components needed are pricey and there are a few ways to save some bucks. But it is also not the place to skimp and do compromising work. Properly done it will add lots of reliability and peace of mind. I believe it also adds some value to the boat.



Good luck
Foster
flee27 is offline   Reply With Quote
Old 21-06-2023, 06:16   #3
Registered User

Join Date: Mar 2023
Location: Chesapeake Bay
Boat: Endeavour 32
Posts: 276
Re: Dumb questions about breakers

Quote:
Originally Posted by catsketcher View Post
I am planning a total rewire of my cat. I have had some good input from forum members, thanks.

I was trying to get the price down of a build your own switch panel. I considered DIN rails but they don't seem to be easy to switch. I could use them as breakers only but I am more likely to use ATO car type fuses that fit in Blue Seas fuse blocks.

The hydraulic magnetic breakers used in most Blue Seas systems are pretty pricey. I can find thermal Carling breakers that are much cheaper and could use them as switches. But I have problems getting them in the correct current rating. 10 or 15 amps is easy, but what about 7 or 3?

When I look at pre-made panels, they seem like they have either 10 or 15 amp breakers. So if this is the case, and if I want to fuse the system for the appliance (most of my circuits are single loads apart from lights) I need a fuse block. (Appliance rated lower than wire)

So are the very expensive Blue Seas panels useful? It doesn't seem as though I can buy them without 15 amp breakers, so what is the point of having breakers if they are not specced for the wire or the appliance? It seems a heap of money to use a breaker (that may be too large) as a switch. In Australia, each hydraulic/magnetic breaker is about $30 and with about 25 switches on my boat, the panels are getting really pricey.

I am thinking I should just go toggles and fuse everything. Then I know that the circuits have proper tripping, either for the wire or appliance. I can still have all the fuses in a couple of places and easily check them. But the pricey Blue Seas panels are really popular. What am I missing? It means more than a thousand dollars for me to go the big Blue Seas panel road and I would really like to save that money.

cheers

Phil
A couple things come to mind

An appliance should be rated lower than the wire supplying it. So, the breaker is sized to protect the wire.

Why would you build a circuit for a 3a load? Add it to a current circuit and switch it at the appliance.
If that single circuit is optimized for for cost/etc...your going to want 30g wire. The smaller the wire, the more fragile it is. That leads to premature failure i. Our corrosive and constant flexing environment. IIRC, ABYC recommends no smaller than 16g wire for circuits.
SY Harmony is offline   Reply With Quote
Old 21-06-2023, 06:24   #4
Registered User

Join Date: Jul 2009
Location: 2024 - Colombia, 2025 - Panama
Boat: Amazon 49 cutter, custom steel boat built in Surrey, Canada
Posts: 845
Images: 1
Re: Dumb questions about breakers

I agree with Harmony. The circuit breaker protects the wire, not the end device or load. I can see no reason you would need a 7 or a 3 Amp circuit breaker. Just use 16 AWG wire or the metric equivalent and make your life simpler.

Also, don’t forget that it’s always good practice to plan for the future. What if it comes time to replace your 3 Amp load and you find the current draw for the replacement is now 4 Amps?

Best of luck!

Steve
steve77 is offline   Reply With Quote
Old 21-06-2023, 06:41   #5
Registered User

Join Date: Sep 2014
Location: Laporte, Texas
Boat: Allied 42 XL2
Posts: 75
Re: Dumb questions about breakers

I have rewired three boats. As I understand electrical systems, the circuit breaker should be sized to protect the wire that leads from the breaker to the device. Thus, the breaker for a 16 gauge wire would be a 10 amp breaker. a 14 gauge wire would be a 15 amp breaker and so on. Then, add an in-line fuse at the device, to get the lower amperage protection.

Putting the minimum size breaker/fuse at the panel can create nuisance trips due to voltage loss in long wire runs and crimp connectors and also due to varying voltage in the boat's batteries; as voltage goes down, amperage goes up per the formula - wattage = volts times amps.


Building an electrical system on a boat to the minimum required will create a system which will give you trouble over time. As Flee27 said, a boat is "not the place to skimp and do compromising work".

I used Blue Sea equipment in all the rebuilds and have not had any problems. Blue Sea is a well-known standard brand and parts are available at local boat stores and some hardware stores. Yes, they are expensive, but they are reliable and, as the saying goes, you get what you pay for. I paid extra for the illuminated labels and pilot light options; very handy at night.

Good luck,
John
crosswire is offline   Reply With Quote
Old 21-06-2023, 06:44   #6
Registered User

Join Date: Jul 2020
Location: Virginia, USA
Boat: Hunter 340
Posts: 1,471
Re: Dumb questions about breakers

Couple things:
1) fuses/breakers protect the wire. You don't tend to see 1A or 3A breaker because usually people don't have wiring limited to 1A or 3A.

2) The panels usually come with some 10A or 15A breakers because they are most commonly used.

3) ABYC requires boat wiring to be at least 16 AWG which is going to be rated for 5A or 10A depending on distance.

4) Yes blue sea is expensive. They are commonly used because they are widely available. Not just initial panel but upgrades and replacement parts.
Statistical is offline   Reply With Quote
Old 21-06-2023, 07:33   #7
Registered User

Join Date: Mar 2021
Location: Flagler County, FL, USA, Earth
Boat: Lagoon 380
Posts: 1,538
Re: Dumb questions about breakers

Is that a multi-pole AC main breaker? it should be.

Also, and way more unusual is a multi-pole DC main. Arguably, useful when lightning in the area to kill both POS and NEG legs for surge reduction. However, if the main also kills bilge pumps, not a good idea.
team karst is offline   Reply With Quote
Old 21-06-2023, 08:16   #8
Registered User

Join Date: Sep 2014
Location: Laporte, Texas
Boat: Allied 42 XL2
Posts: 75
Re: Dumb questions about breakers

AC mains should be double pole.
DC mains can be single pole.
Bilge pumps, gas alarms, CO detectors, etc. should be on separate, "always hot", feeds from the batteries with separate over amperage protection for each device. Blue Sea has pre-built panels that help address this need.

The "always hot" feeds do create a need for a way to keep the batteries charged if the boat is used infrequently.

John
crosswire is offline   Reply With Quote
Old 21-06-2023, 08:32   #9
always in motion is the future
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 20,159
Re: Dumb questions about breakers

Here’s some panels from FrontpanelExpress.

The DC Distribution panel shows the breaker values clearly. 15A is a standard value and supports most AWG14 circuits on boats, while the wire can take 35A without burning so a good safety margin.

The 50A breakers have 6AWG wire and go to small BlueSea fuse blocks with the familiar automotive fuses. These cabins even have a small inverter (this is 24V).
Attached Thumbnails
Click image for larger version

Name:	IMG_2066.jpg
Views:	177
Size:	409.8 KB
ID:	277072   Click image for larger version

Name:	IMG_2084.jpg
Views:	159
Size:	421.9 KB
ID:	277073  

__________________
“It’s a trap!” - Admiral Ackbar.

s/v Jedi is offline   Reply With Quote
Old 21-06-2023, 08:33   #10
Registered User

Join Date: Oct 2016
Location: Monroe, Ga
Boat: 1987 Sabre 42 C/B
Posts: 417
Images: 1
Re: Dumb questions about breakers

Quote:
Originally Posted by team karst View Post
Is that a multi-pole AC main breaker? it should be.

Also, and way more unusual is a multi-pole DC main. Arguably, useful when lightning in the area to kill both POS and NEG legs for surge reduction. However, if the main also kills bilge pumps, not a good idea.
If your question about the AC main breaker being multi-pole is in reference to my panel the answer is yes, it is a multi-pole breaker.

Foster
flee27 is offline   Reply With Quote
Old 21-06-2023, 08:39   #11
Registered User

Join Date: Jun 2019
Location: Rochester, NY
Boat: Chris Craft 381 Catalina
Posts: 6,991
Re: Dumb questions about breakers

If it's going to be a single device circuit, I see no reason not to down-size the breaker closer to the expected draw, that way it can offer some protection to the device as well as the wire.
rslifkin is offline   Reply With Quote
Old 21-06-2023, 08:46   #12
always in motion is the future
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 20,159
Re: Dumb questions about breakers

Quote:
Originally Posted by rslifkin View Post
If it's going to be a single device circuit, I see no reason not to down-size the breaker closer to the expected draw, that way it can offer some protection to the device as well as the wire.
In theory, yes, but devices that need protection take care of that themselves.
__________________
“It’s a trap!” - Admiral Ackbar.

s/v Jedi is offline   Reply With Quote
Old 21-06-2023, 09:16   #13
Registered User

Join Date: Mar 2021
Location: Flagler County, FL, USA, Earth
Boat: Lagoon 380
Posts: 1,538
Re: Dumb questions about breakers

very nice panels Jedi; even a newbe can follow the source/load switching paths.
team karst is offline   Reply With Quote
Old 21-06-2023, 11:33   #14
Registered User

Join Date: May 2016
Posts: 108
Re: Dumb questions about breakers

Here is a good link for figuring cable sizing

https://boathowto.com/wiresize/abyc/
Senojev is offline   Reply With Quote
Old 21-06-2023, 13:30   #15
always in motion is the future
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 20,159
Re: Dumb questions about breakers

Quote:
Originally Posted by team karst View Post
very nice panels Jedi; even a newbe can follow the source/load switching paths.
Thank you, a multi-discipline job
__________________
“It’s a trap!” - Admiral Ackbar.

s/v Jedi is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Dumb DSC VHF questions Gary H Marine Electronics 16 03-12-2013 06:46
are "dumb" questions dumb, or ... sailorboy1 Our Community 27 20-11-2013 07:53
Hello, I Am a Pro Boater with Dumb Questions! whiteH2Okayaker Meets & Greets 20 14-04-2010 15:17
Pardon These Dumb Questions - drew.ward Cooking and Provisioning: Food & Drink 14 04-06-2009 04:13

Advertise Here


All times are GMT -7. The time now is 21:00.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2025, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.