50mm2

[capta]

I have just spent a huge amount of time on the internet trying to find the US electric cable gauge equivalent to 50 mm2. Why do the Europeans have to befuddle my old mind so?
I am trying to figure if the cables I have will run the new windlass. Since they are both 1200w units, I see no reason why not. But just to check it, I read the Lofrans instructions and they gave me that figure (50mm2) as the proper wire size.
From what I found on the web, that is .63" diameter, or 7/0 gauge, which seems a tad large for a 30' run at 100 amps.
Help, please.

 

[Rocket1]

1/0 AWG = ~53mm^2

Per ABYC calulations, assuming a 30' one-way run (60' round trip), 1/0 AWG should be adequate. You would see about a 5% voltage drop, which would be acceptable for a "non-critical" component like a windlass. The other thing to consider is that this is a short term load, not something that you're going to be running for extended periods.

To get to a 3% voltage drop (recommended for critical instruments and systems), you would need to go no smaller than 3/0 AWG.

Myself, personally, I would probably split the difference and go with 2/0 AWG - though some may disagree. One thing is for certain - better to go too big than too small. At any rate, this should get you in the ballpark.

Cheers!

 

[Bill Roosa]

pi * (D/2)^2= area -----> diameter is in mm, area is in mm^2!!!

If the manufacturer is calling for 50mm^2 and 1/0 is 53mm^2 I'm thinking you should be ok

 

[capta]

Thank you both very much.
I have 1/0 presently, though it's pretty old, it seems to be in great shape (I cut off the lug at the windlass end and there wasn't even the tiniest bit of corrosion), so I think I'm OK for now.
We always have the engine (105 amp alternator) or generator (80 amp charger) running when we pull the anchor, so a 5% voltage drop still leaves me way above 12.2 volts.
I would like to redo the wires one day, but since we are at anchor in the Caribbean in hurricane season, my priority at this moment to get the new windlass operational.
Again, thank you both very much.

 

[Ron20324]

Oh, if people would use that most basic source of boating information- the West catalog. Page 422.

 

[Ralph Johnstone]

Far Too Simple .............................

Oh, if people would use that most basic source of boating information- the West catalog. Page 422.

NM

 

[capta]

Thanks for the info on the WM catalog. I'll just what, run, swim, fly, drive to the nearest WM to Prickly Bay, Grenada and get one.
I've enough stuff aboard w/o carrying a catalog that I'd use once in a blue moon for something like this, 'cause I certainly won't be buying anything from it.
But thanks anyway.

 

[Stu Jackson]

capta, no you don't have to lug the catalog along with you. Since you have internet access, it's right at your fingertips.

http://catalogs.westmarine.com/WebProject.asp?CodeId=7.7.1.22&BookCode=wmm#

BTW for other readers of this board, Ron's right, and I have been suggesting that folks get two of the catalogs, one for the boat and one at home, but you can use the 'net if you want. They also, if you don't know, have a great series of Advisors, both online and in the catalogs.

You have a pretty big boat. A friend with a Nordic 44 asked me to look over their electrical system before a race to Hawaii. After discussing some stuff, I asked if they had a WM catalog on board. His wife said, "You know, a lot of people say that same thing, so we went out and got one."

It's a great resource. So are Calder's books, and I know his Boatowners Mech & Elec "bible" has that same wire info.

Fascinating that Google couldn't help you with that conversion.

In any event, glad you got what you needed and that things will work out for your new installation.

All the best,

Stu