AWG size?

[Tom T]

I need to run a 125  line to a 100 amp service off of the main box cant find my books to tell me how to figure the size of coper to use. Can some one help me ? Of all the things I have lost I miss my mind the most.Tom T

[bschwartz]

I don't have an answer, but I think to get one, you will need to know the distance of the run.

[LowGear]

I think that's a 125 foot line of 240 volt service rated for 100 AMP service.  I'd ask about aluminum if you're buying new or shopping craigslist for used.

Casey

[Geno]

Check your local codes but this calculator should give you the answer.

http://www.elec-toolbox.com/calculators/voltdrop.htm

Thanks, Geno

[mike90045]

What's the LOAD you will be expecting ?  Starting currents for motors is 3-10x running load, and if you sag too low while starting, you will overheat the start winding.

And it's not 125' of wire, you will have 250' of wire.

I used #6 alum for a 900' 240V 30A run. Gotta have my pump start OK.

Alum is 2 gauge sizes larger than copper, so if #8 copper is called for, #6 alum is equivalent.

And use alum rated gear, if you use alum wire.  Make sure breakers and splices are AL spec.

[LowGear]

Wow Mike90045,

You don't want to see what this calculator says.  And always, always use the anti oxidation goop on aluminum.  Here in Hawaii I even use it on copper.

Casey

[mike90045]

Wow Mike90045,

You don't want to see what this calculator says.  And always, always use the anti oxidation goop on aluminum.  Here in Hawaii I even use it on copper.

Casey

Goop was used.
  I did the best within my budget.
The pump calculator was way more relaxed than this web calculator.

[LowGear]

Hi Mike90045,

The calculator is for a sustained 30 Amps with at least the NEC 20% safety margin ta-boot.  You may even have one of those varible speed pumps that doesn't surge or suck within sight of total shunt to get started.  My guess, without knowing your system, is that you don't even pull 7.5 Amps once she's got water moving.

Casey

[Tom T]

Thanks for all the input. The max amps will never every high  am putting in a new well and pump am using a 100 amp main and brake it dow from there. Will be using copper wont use alum. He started drilling this am 6:45 need to go down about 250' or so but never no on that part.  And its three wires I need to pull not two the groung can be smaller than the others and will be in #8 I have a very large spool of it but no #4 or #6 :(Tom T

[LowGear]

I'd contact the pump manufacture.  Good juice make them pumps pump longer and harder.

Casey

[mike90045]

Well, while reading around here: http://www.inspectapedia.com/aluminum/aluminum.htm   I found that the no-ox goop I used, is flammable !

But I found a plethora of other good wire info there, and some nifty copper/aluminum splice gizmos
http://www.tork.com/electrical/insulatedconnectors/polarisblack.aspx
and terminal blocks too http://www.tork.com/electrical/connectors/connector-bloks.aspx  that will, for a price, take out a lot of the split bolt agony.

[Tom T]

Casey what you say % true but thats just from the mainto the pump not from the main box and wont know wht the pup is untell the well is down for the depth and GPM .He got down 25' today.  Tom T

[LowGear]

Hi Tom,

Yeah, I agree.  I think the manufacture could give you a very accurate number though including expected line drop for the 250' down the hole.  You'll have already installed the pump and wire before you can take your own in-house data.

Casey

[mike90045]

Submersible pump wire is sold, either as 3 or 4 wire twist, or flat jacketed, copper.  It's crimped onto the pump leads, and then heat shrink with encapsulent is shrunk over each wire.  After the drilling is done, the well folks use their pump, and test it out, and are likely to tell you to hang the pump at the 198' level, or where ever they think is best for the amount of draw you plan on.

[LowGear]

Well I've shown my age again.

They actually attach the wire for you and use a waterproof shrink wrap?  Shazaam!  This modern world is such a wonder.

How many gallons a minute are you hoping for?  What make and model of pump are you going with?

Thanks for your patience.

Casey