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Old 29-06-2012, 18:12   #1
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wire ga. ????

radio panel ready for final install
can't find anything on what wire size to use. Friend suggested 22ga. is that right?
Will using 18 require more battery to push the power?

Noobie appreciate the support!
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Old 29-06-2012, 18:24   #2
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Re: wire ga. ????

What do you mean by radio panel?

Most people usually use no smaller than 14ga. But like all things magic fire it's all dependent on the amount of current being used.
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Old 29-06-2012, 19:09   #3
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Re: wire ga. ????

If your wire is too small adding "more battery" will not help. You will still see a voltage drop no matter how big your battery and if the wire is too small for your load the wire will get hot, maybe melt or catch on fire.

Like SM said, have to know what a radio panel is and how much power it will draw. Somewhere you should see a rating in Watts or Amps for whatever it is. Know that then you can calculate what gauge wire to use.
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Old 29-06-2012, 19:09   #4
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We usually look at length of wire run and Amos device rewuires. Probably 14 gauge is fine but there are very easy to find wire size recommendations by amp load. You usually use both pos and neg for length cacs. 22 is way to small for most anything barring data.
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Old 29-06-2012, 19:44   #5
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Re: wire ga. ????

Using 18 gauge will not require more battery(amps) power,,unless its real shi**y wire.
Skipmac said it best,,small gauge with large load or amps and you got trouble.
It's ok and in most cases Safer to run larger gauge wire just use a fused link between your radio panel and the larger gauge wire, if it trips you want it to trip on the Radio side of the Wire.
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Old 29-06-2012, 20:06   #6
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Re: wire ga. ????

You need to be a lot more specific. Specifically, what loads (in Amps) are being connected through this panel? For example, my SSB has a 30A fuse, so I use 8ga to the batteries; my VHF draws perhaps a quarter of that (no, I'm not going to look) and I would have used something between 12 and 16. There is precious little that I would hook up with 22ga wire - it would have to be something like a single LED bulb.

When you are more specific, I'm sure you will get lots of useful advice. The ABYC publishes tables of loads vs lengths, with gauge sizes, for typical applications. You should be referring to those.

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Old 29-06-2012, 20:16   #7
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Re: wire ga. ????

ABYC currently says that you shouldn't run anything smaller than #16 AWG wire for DC power. You need to know the max possible load for a wire, which is usually the same as the breaker or fuse for the circuit. More current = thicker wire. Then, there's length of run, where it's run, and how many are bundled together. Fun, no?

Here's an online calculator
to simplify the process, but if this is all greek to you, it would help to read a decent book on boat electrics to demystify it.
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Old 29-06-2012, 20:36   #8
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Re: wire ga. ????

Quote:
Originally Posted by colo.sail View Post
radio panel ready for final install
can't find anything on what wire size to use. Friend suggested 22ga. is that right?
Will using 18 require more battery to push the power?

Noobie appreciate the support!
Smaller gauge numbers are physically bigger wires able to carry more current without incurring a voltage loss.

22 is minuscule.

You need to look on the piece of equipment and see what the info tag says for amperage. If you have more than one piece of equipment on a circuit you need to add up all the nameplate amperage's.

Measure the length of the wire run from the distribution panel and double that.

Using the length and amps determined in the previous 2 paragraphs, check for the wire size from the table at this link: Amps and Wire Gauge - 12V Circuit

This table was the first result from a google search for 'wire size of 12volt electrical system'

If you are just on the cusp of needing a larger wire size, go with the larger size, the marginal cost of the larger wire now is nothing compared to the cost of replacing the wire in a year when you add a piece of equipment to the circuit in a year.

Oh yeah, one last thing. DO NOT USE HOUSEHOLD WIRE. Two reasons.
1) Most household wire is solid wire that won't hold up well to the constant flexing on a boat. IF it breaks clean annoying. A partial break can create a hot spot that starts a fire.
2) Marine wire is tinned, so it doesn't corrode in the marine atmosphere. Household wire will be a gooey green mess of corrosion products in several years and many of your joints will be creating a lot of voltage loss and you will need to replace the system.
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Old 30-06-2012, 14:44   #9
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Re: wire ga. ????

A better explanation ...
my radio panel - the panel with all the radios mounted .... is, the nav station. VHF, GPS/Sounder, Radar, AM/FM car radio and the lights switch panel (running, anchor, masthead, etc.) and battery monitors.

ICOM 700 SSB is on a shelf nearby.

We were going to wire all the instruments to one 8-pin panel/block from Radio Shack (or another as recommended by you wise sages) and then one-lead to power supply. Between the instruments and the block is what I was inquiring about, all individually fused, since not quite ready to do the box to battery leads yet.
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Old 30-06-2012, 15:29   #10
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Re: wire ga. ????

You need to determine what is the most current that will ever go through that wire and then gauge it for no more than a 3% drop, or nothing less than 16 gauge wire, whichever is larger wire. That is the bottom line.

Each load on that circuit should have its own fuse and the circuit should be on a breaker.
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Old 30-06-2012, 16:31   #11
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Re: wire ga. ????

So I take it that the Icom 700 has its own wiring, separate from this panel (as it should be). SSBs are wired direct to the batteries, with their own fuses/switches.

Just estimating from what you have written, this panel will need to be wired to a 15A or 20A circuit breaker on the main panel - BUT this MUST be calculated by adding up the loads, not guessed. And, depending on the length of the run and other variables and calculating as described above, you will probably want to use a 12ga cable between the main panel and this panel. The problem is that the total voltage drop that the load will experience is a combination of the drops from the instrument to the new secondary panel, from the secondary panel to the main panel, and the main panel to the batteries. The combination must not be more than 3%, and less is better. So going large on the battery to main and main to secondary is usually a good idea.

Usually the equipment mentioned has its own power leads attached (except for the lights), with an inline fuse on each one. If not, you will need to add an inline fuse on each electronic instrument or in the panel. Be sure to use the fuse size and type specified for the equipment - electronic stuff often calls for fast-blow fuses. Since these leads are going to a secondary panel, the panel is (should be) pretty close to the equipment and in most cases the factory cable should reach. If one has to be extended then use a larger size wire for the extension (it really would be better to calculate though). If the instrument doesn't have a power lead you might take a look at the instructions - these days many instruments have a table of recommended wire sizes in the manual.

I am more than a little put off by the concept of using RS components on a boat. They are not in any sense marine grade, and would be prone to corrosion and failure. If it is worth your time and money to do this job, then do it right. A marine grade panel and marine grade wire are really not that much more money. BTW there are other, less expensive, sources of marine grade wire than Ancor - I have been using Cobra wire and save nearly 40%.

Greg
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Old 30-06-2012, 16:35   #12
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Re: wire ga. ????

I should add that I would be tempted to use two terminal strips, and then a small panel if needed for switches/fuses for those devices that don't have internal switches. These days most electronic equipment have their own power switches so there is no need to duplicate. Just run them, with their individual fuses, to the terminal strip and then run the strip to one circuit breaker on the main.

Greg
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Old 30-06-2012, 17:35   #13
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Re: wire ga. ????

Quote:
Originally Posted by colo.sail View Post
A better explanation ...
my radio panel - the panel with all the radios mounted .... is, the nav station. VHF, GPS/Sounder, Radar, AM/FM car radio and the lights switch panel (running, anchor, masthead, etc.) and battery monitors.

ICOM 700 SSB is on a shelf nearby.

We were going to wire all the instruments to one 8-pin panel/block from Radio Shack (or another as recommended by you wise sages) and then one-lead to power supply. Between the instruments and the block is what I was inquiring about, all individually fused, since not quite ready to do the box to battery leads yet.
Instruments/radios to block: Assuming short, protected runs, AWG#18 is safe for 10A so it would probably be OK. ABYC spec's AWG#16 minimum at present mainly because of its physical properties - the thinner the wire the more chance of breakage or cable injury when it's being installed. ABYC may at some point approve smaller gauge cables when they are sufficient (eg LED lighting, devices taking less than 10 A) AND when the wire pair is suitably jacketed for protection.

Rather than terminal strips, it might make more sense to buy two buss bars (+ and -). Are your fuse-holders inline, or mounted?

What size breaker or fuse is on the DC circuit that will feed this system? It needs to be big enough to not blow when every device wired to the buss bars is on and VHF is transmitting on high power. Then, the wires from DC panel to buss bar must be sufficient to carry the trip current of the fuse or breaker.
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