Electrical Distribution (DC) Panel Questions

[Paul S]

Jim
You might want to look at one of these:
http://www.defender.com/product.jsp?pat ... id=1131356

About $60 cheaper and waterproof which is not a bad idea as close at it will be mounted to the main hatch.

Mark

I would still go with breakers over fuses.. thats just my preference.

If the panel is going to THAT wet.. chances are you have other big issues to deal with

[bastonjock]

fuses are a better option than breakers,when a breaker trips you should replace it,most people just reset it,each time that a breaker trips it becomes weaker.

[KayakDan]

I have the same fuse panel that Paul has,and it is backlit. It's a great choice. I may add a second small panel,as Paul did. I have one open circuit,that I'm saving for my fridge/freezer,but I used all the others,and I will probably want to add more toys later on.

I would rather have the option of quickly resetting a breaker,rather than go rummaging for a replacement fuse.

[Highlander]

Bastonjock

I'll have what ever your Drinking make mine a triple , where did you get this theory or info from

J

[Hardcrab]

I'll have some of that also.
I do know that circuit breakers are not infallable. I've changed a few "weak" breakers (trip before rating) in my 30+ years aviation electrical experience, but never replaced one simply because it tripped. Unheard of in my line of work.
If 100% protection of a current sensitive circuit is desired, then fuses are called for.
The current ratings for fuses can be made very precice and repeatable unlike breakers. (Unless you are in space. No gravity to break the molten fuseable material)
The standard usage refered to in this post is sledgehammer protection. Simple protection for dead shorts or gross overloads to protect the wiring from overheating. Breakers do great in this area.

[The Mutt]

If you want quick acting isolation, use fuses, circuit breakers trip a little slower than a fuse making them perfect for a dead short, we use a circuit breaker with built in voltage readout for our two 6v deep cycle batteries wired in series(giving us 12v/225 Amp Hr) installed in our 4WD they run our fridge/freezer, LED camp lighting and shall eventualy be connected to the Macgregor's power line via an Anderson Plug to keep everything charged while being towed, for any reason that a dead short happens then the alternator and cranking battery are protected, in low amp situations like the radio power line I us a fuse.

It is an Urban Myth that a Circuit Breaker has to be replaced after tripping, if that was the case the Power Companies wouldn't be using them, like all electrical equipment they can become faulty and need replacing, generally when they keep tripping and won't stay engaged.

Glenn

[dvideohd]

A short word about Fuses and Circuit Breakers...

You can TAILOR the break characteristics of the fuse or circuit breaker... slow blow, fast blow, etc.....

BUT THE PURPOSE OF EITHER ONE IS SAFETY - it's not going to protect a piece of expensive electronics from shorting out or blowing... The purpose is to prevent a fire or unsafe SHORT!!!!! It's convenient when you can put a switch with it... It's an awareness that we have to be sensitive about corrosion and poor wire characteristics... but the Fuse or Circuit Breaker won't stop that problem either!!!!

Defense in depth is a GOOD idea... An AC line should have a two pole breaker on the input.. Each distribution leg has a 15A breaker.... Each AC socket has GFI (though that is technical overkill.. I just wanted simple wiring... )

DC equipment should have overvoltage protection... and fuses, too...

None of these things will protect from a solid lightning strike...

So while a precisely tailored fuse might be better in a narrow sense... the USE of a circuit breaker is much better from a human standpoint... ALSO - there are a lot more points to look at with your dollars than the difference between a fuse and a circuit breaker....

*************

Still... both work.... so what ever makes you happy!!! Jus look at the whole wiring grid to see if you are in good shape! Have you changed out your zincs (if you have them) lately (if you need too...) . Do you have AC? do you need a galvanic isolator (ie, a corrosion path)?

--jerry

[bastonjock]

Bastonjock

I'll have what ever your Drinking make mine a triple , where did you get this theory or info from

J

It comes under the 16th edition of the IEE regulations for Electrical installations at work.

I am a qualified UK sparkie,our regs are different from the states,whilst breakers are aceptable in a domestic installation,the book says that they should be changed after they have tripped

I have built and comissioned controls systems for years,i have seen the train of thought change from fuses,to breakers and back to fuses, a lot of it depends on the consultant engineer

[dvideohd]

The UK is a different animal... I have seen two wire AC sockets in older UK homes and some hotels...... Strange wiring also... so I know there are likely to be "special considerations" to deal with these things... I have a socket tester for the AC power in my home - and I periodically go do "plug in" checks of the AC socket - and check the socket power function... I have found bad sockets... It is possible - that it could cause a breaker to go, too....

I think there is a line somewhere that says a breaker can fail.. but a breaker is not a fuse... If I had a breaker that failed repeatedly... I would worry that (a) there's a very good reason... and (b) it is possible - but unlikely - that the breaker is "going bad"...

I have Aluminum wiring in my house.... turn on the microwave and coffemaker --- it blows a circuit - as it should.. I worry about Al wiring a good bit.. I added GFI sockets to all outside power - and selected internal power... I think these were pretty important things to do....

I likely won't be replacing breakers if they blow - I sure will be trying to find out why....

************

--jr

[MadMacX]

Guys, chill a minute. We are talking about DC power (12V) not AC (120/240V). That's a whole different animal when we are talking about circuit breakers. 120/240V can kill on contact and should be handled differently than 12V. !2V can kill, but not directly (fire from short). I have worked in environments that were required to replace a tripped 120/240 breaker if it had tripped more than twice. The reason I was told, was that it is a safety consideration.

FWIW, I have four ETA AC240V/DC28V breakers on my boat. One controls the shore power side of things and the others control various 12V functions (GPS/Plotter, depth finder, autopilot). Everything else is on fuses (lights, stereo, mast lights etc.). IMO, if the wiring was done correctly, and according to code, you should never have to worry about resetting a breaker or replacing a fuse. Why do I have a combination of breakers and fuses......because I wanted it that way. Both work equally well at what they do!

BTW, has anyone looked at the March issue of Sail, page 56? It has a nice article on custom made electrical panels. I used to wire race cars and we made our own aluminum panels on a Vertical Milling Center. I guess I was just never smart enough to try and market them. It's a good idea.

Pat

[Highlander]

Pat

Better do your home work a 12v Alternator or ign. system if not handle properly can stop your heart ? , Fry your Brain ? and even Kill Ya ! ?

J

[dbcounihan]

It's not the voltage, it's the amps that will kill you. Given the right (Wrong!) circumstances, a 12V battery can kill you
if the amperage interrupts your heart. I remember back in the early 70s when Mercury came out with its 50,000V
ignition system on its outboards. We had a mechanic who used a screwdriver to check the voltage get launched
out of the boat, over the pier and into the lake. Fortunately for him, the amps were very low.

[MadMacX]

Pat

Better do your home work a 12v Alternator or ign. system if not handle properly can stop your heart ? , Fry your Brain ? and even Kill Ya ! ?

J

Ah, I've spent quite a bit of time around 6, 12 & 16 volt systems and, yes, if you are stupid enough, you can hurt yourself, but if I read Jim's original post correctly, he will be working on the other side of the system, not the ignition or charging side!!

I think we all agree that if someone were to decide to lay their tools across the terminals of the battery while they are working, well, that might hurt, but it would also be stupid. If you decide to grab the high tension side of the ignition system while you are starting or running your engine, that too will hurt, if not stop your heart, but again that would be stupid But, if you are wiring in a new panel you should only be working with the battery, hot and ground and the engine should not be running. If you screw those up you might burn a wire, blow a fuse or trip a breaker, but you are not going to kill yourself. Screw up on a 120V system, well....that's going to really hurt. My only point was that the discussion was getting into residential/commercial wiring of 120/240V systems and that had nothing to do with the OP. If I misspoke or offended someone, please accept my apologies.

Pat

[dvideohd]

i guess we should more carefully separate the AC and DC section discussions...

But on boats, if it is electrical - it can tie into some other electrical system... I think if possible for AC on one device to find some way to get on another - nominally DC device. I have certainly seen it happen. I can understand that if some sections get corroded - then the GROUNDING can fail - and again cause another potential issue...

It seems that using Fuses instead of Breakers - on DC - might not be necessary.. but as part of an overall stategy to maintain the power systems in "Bristol" condition - it could be a good idea. Just part of tight control on systems integrity... That's what will keep our boats in good shape forever - Keeping a tight reign on anything that might give advance notice of a problem is a good thing.. You could be more likely to get that notice with a sensitive fuse.... and therefore have a good reason beyond the technical merit of "does a breaker work"....

--jerry

BTW... I have seen sttrange failure paths where a DC power supply failed - and it led to 120VAC showing up on the chrome trim of a consumer product... I am not, as you might guess, a fan of chrome trim - or exposed metal - on consumer products....

[The Mutt]

I thought we were talking DC power in Australia you have to be a qualified electrician to work on 240 VAC.

Glenn