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Ancor wire calculator/6 AWG ?

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ct95949
Captain

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Aruba
300 Posts

Initially Posted - 02/24/2006 : 16:41:14

I was recently advised that the wiring in my boat may not be big enough and after doing some research I've found that advise may be correct.The wire from my house batterys to the main panel is 10 gauge duplex which I sized based on a 30 amp circuit in my home.If every thing in my 12V system was on at once it would draw about 30 amps.It is 10-12 feet from the batterys to the panel.

OK. Go to the West Marine and Ancor wire calculators which say to measure the run from the batterys to the panel and back or 'round trip'.A 30 amp circuit going 20-25 feet would need 6 gauge wire

I have no problem spending the money to over build my wiring but am I the only one who thinks 6 gauge may be a little over the top?
What is happening in the real world? How many of us have actually done this? And I want to here from all the normal guys not just the over acheivers

Thanks,Craig

'90 SR/WK #6017. PO of '79 SR/SK.

Edited by - ct95949 on 02/25/2006 09:19:52

RickStevens
1st Mate

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USA
62 Posts

Response Posted - 02/24/2006 : 16:55:23

Normal?

Edited by - RickStevens on 02/24/2006 16:55:45

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 02/24/2006 : 21:44:20

Here you see the big red 6 going from the batteries to the Guest battery switch, the yellow crimped connectors on the factor 10 that runs around the boat and my 12 that I have run short distances, (main salon only) with the red and blue crimps.

Edited by - on

Sea Trac
Master Marine Consultant

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Vanuatu
1357 Posts

Response Posted - 02/24/2006 : 21:57:42

Ha ha! Real men use 0 gauge across the batteries, to the Guest switch and to the panel. (Only because it was available and free.) If I were spending the money, I'd go with 6 gauge, because anything larger is EXTREMELY difficult to run, besides being total overkill. I also have factory 10 gauge throughout, except for short instrument runs which are 12 gauge, like Frank. Originally, the battery was wired to the panel with 10 gauge.

Edited by - on

Happy D
Admiral

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921 Posts

Response Posted - 02/25/2006 : 06:29:08

I have calculated the required wire size for my system based on Famsp. Using the ABYC TABLE II - ELECTRICAL LOAD REQUIREMENT WORKSHEET, I have 32.07 amps load to the electrical panel. 30’ round trip.
30' x 32.07 = 962.1 Famps. (feet/amps)
My wire runs through the engine room, I have an inboard engine and I only want a 3% drop in voltage.
My electric distribution panel is rated for 100 amps.
Using the Blue Sea wire sizing chart:
#6 wire is rated for 879 Famps, 102 amps in the engine room.
#4 wire is rated for 1398 Famps, 136 amps in the engine room.
When I add in my starting load to the calculation for the house batteries, the wire size jumps up to #2.

However, the starting load is not 30 feet, it's only 10 feet from the house battery to starter, and that is only if I need to start the engine using the house battery furthest from the engine, so #4 wire is OK. Starting load is 100 amps continuous cranking. The <i>starting</i> battery is only 2’ from the engine.

I am having the wires (#4) made to length by Genuine Dealz in Louisville, KY. They have the best price going. They will professionally crimp the battery lugs and shrink tube them for $.99 each. The wire is made in the USA, that is important to me.
I have 100 amp fuses at the batteries. Since my fuses are in the compartment with charging batteries, I am using ignition protected fuses.

Edited by - on

ct95949
Captain

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Aruba
300 Posts

Response Posted - 02/25/2006 : 09:18:28

I had already ordered the 6 gauge when I posted this question but I still couldn't believe I needed to use something that big.Two other questions:do I need to buy a big expensive crimper or is there another tool that would work? I want to do the work my self on the boat.And I will be installing Blue Seas Maxi Fuse Blocks at each battery which accept 30 to 80 amp fuses.Since my system would draw 30 amps max I had planned on using 40 amp fuses.It seems like a fuse should be rated only a little above the maximum draw so it would blow if a short started heating things up.Is that correct?
Thanks,Craig

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 02/25/2006 : 11:49:43

Craig,<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">...do I need to buy a big expensive crimper or is there another tool that would work? I want to do the work my self on the boat.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">I use the smaller of the bolt-driven Nicopress swedging tools to crimp terminals on large wire. It was inexpensive and has come in handy. I also solder and heat shrink after crimping. I think soldering and sealing is an especially good idea were wires might be exposed to out-gassing fumes from lead/acid batteries. If using solder, be sure to thoroughly wash off the corrosive flux residue with full strength alcohol (shellac thinner).

-- Leon Sisson

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ct95949
Captain

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Aruba
300 Posts

Response Posted - 02/25/2006 : 15:26:17

Thanks Leon
Are you talking about the same kind of tool that is used to swedge lifeline terminals? If I heat shrink then I should be able to use uninsulated cable lugs which should be easier to crimp?

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 02/25/2006 : 17:59:27

Craig and Lorri,

Yes, this thing (the smaller one):
<center>

</center>
Yes, unisulated terminals w/heat shrink. The insulated crimp on terminals for small wire (up to about 10ga.) are intended for fast cheap installation. I know others will defend insulated crimp terminals. I've had formal NASA training in their proper installation and use. I still don't like 'em. It's a personal bias. For anything more critical than a car stereo, I prefer crimp - solder - wash - heatshrink. Especially in a corrosive or moving environment. For extra sealing, you can smear on a bit of silicone sealant before sliding the heatshrink into place. Then go easy on the heat to avoid overcooking the silicone. For extra strain relief, you can add a second, longer, layer of heat shrink tubing.

-- Leon Sisson

Edited by - on

mashedcat
Navigator

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USA
194 Posts

Response Posted - 03/01/2006 : 16:46:31

If you do a google search for WireSizer 2.0 you can find a free download to do all your calculations. I never looked at the Ancor one so i dont know which is the better deal

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