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Old 12-09-2008, 06:35   #1
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Electrical help needed please

I am new into sailing/boating in general and have a question about a distribution panel - or switch panel (whichever you want to call it.) I just picked up a 5amp switch panel that I am going to hook my battery up to it. I know it is on the small end of the spectrum in terms of amperage, but can I still use this switch board to run my running lights, cd radio, stereo, cabin lights, etc?

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Old 12-09-2008, 07:05   #2
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5 amp switch panel

Here is what you must know, and there is no magic here:

P=VI or in words power = voltage X current
Power(P) in Watts, Voltage (V) in Volts, Current (I) in Amps

You have not said so, but assuming you are speaking of boat power then:
Nominal 12V battery case:
P=12V X 5A= 60Watts Maximum
Add up your loads. If they exceed 60W you will blow the breaker. You could just run one thing at a time (if under 60W) and then the breaker will only blow if you switch anything else on.

In the shore power case with V =120V,
Nominal 120V shore power case:
P=120V X 5A= 600 Watts Maximum
Add up your loads. If they exceed 600W you will blow the breaker. You could just run a few things at a time (if under 600W) and then the breaker will only blow if you switch anything else on.

So what you have learned here is that 5 Amps is a small load. It may have a use, but if you need to drive more electrical and electronic appliances (and what boat ( Bring On All Technology) doesn't), you will need additional breakers or a breaker of increased amperage.

The next issue is wire sizing. All conductors are sized to handle a specific amount of current. I am sure that someone will explain this, if this has not already answered your question.

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Old 13-09-2008, 09:23   #3
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By panel - I assume you have multiple switches with 5amp breakers. They are breakers not fuses, right?

Because it's not clear by your post but you want to run these things on separate circuits.

IIRC correctly - here's how our panel is split up

10 amp - running & Steaming lights
5 amp - anchor light
10 amp - vhf
10 amp - autopilot
10 amp - cabin lights & outlets (fans)
5 amp - instruments - depth & compass light.
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Old 13-09-2008, 09:47   #4
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I STRONGLY suggest you not do any electrical wiring to your boat at this time. A mis-step can cause a fire at worst or serious damage to other electrical circuits on your boat at best and if you are in a marina the results could be devastating. You really either need to acquire a great deal more knowledge or get the help of a knowledgeable individual before you start and as you progress. Get a copy of the 12 Volt Bible and study it thoroughly. Obviously from your question this is not something you should tackle at this point by yourself.
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Old 06-11-2008, 23:21   #5
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I have to agree with Chuck mate. If you want get a good book like Marine Electronics Bible or any other that looks like starting out wit Electronics for Dummies and then getting serious. You can do major damage, start fires, distroy thousands of $$ in equipment, maybe even kill yourself by getting it wrong. We all started out knowing zip about this stuff and learned along the way so be smart... learn now and try to avoid all the mistakes I am sure I and the others in here could tell you about... if we were drunk enough to be honest that is.

Some very basic tips:
Always use very thick wire for DC runs. The smallest should be 2.5 mm and I really mean smallest, like for a GPS or small LED. 6mm is usually more like the real thing.

Use the best switches you can find. I always use Airpax simply because they are tested and then tested again for commercial aircraft and are really what they say they are, not like most "marine" switches. Trick: Check at the airport maintainance facilities. They often have "out of date" ones you can get for peanuts or a case of beers for a dozen. That has to do with the rules for aircraft not if the switches are good or not. Otherwise think 100+$ each.

Take your electrical system seriously, very seriously and it will give you years of trouble free service. Fail to take it seriously and well its your back side after all....

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