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Thread: 220 Ext. cord

  1. #11
    What about the orange colored extentions we usually buy at home depot to use power tools outside, will they work?
    I have a 220v 200PI.
    South Bend 9"x36" Precision Model A. Woohoo!
    Sherline lathe and vert mill.
    Weller soldering gun.
    Pair of pliers.
    Some glue.
    Lincoln mig Weldpac 100.
    200PI tig .
    An extention chord.
    And a boat.
    HF 21 Gal vertical compressor.

  2. #12
    Senior Member mountain eagle's Avatar
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    Not sure about that. What gauge wire is in the cord? Typically most extension cords are actually undersized unless you go out of your way to find and pay for something heavy duty...... which is typically 10awg and still only good for 30A. The general rule of thumb, or NEC 310.15(B)(16) formally known as Table 310.16, is that 14awg is good for 15A, 12awg - 20A, and 10awg - 30A, 8awg - 40A, 6awg - 50A. Phrasing it like that is just a general rule too... there's exceptions and temperature factors, insulation, conductor material that all change the rules, thus saying the general rule. A little cya wording there. Please keep in mind that article 400 and table 400.4 actually govern flexible cords and cables. Any extension cord or flexible cable will have markings that tell you exactly what it is intended for and what it's characteristics are. I've never actually looked tho.... I'll make point of that today. PPE is portable power cable, as is G and G-GC. Then there are 27 different hard service cords made for specific applications.... often damp and or wet location being part of it.

    One thing to keep in mind is voltage drop. Branch conductors (your extension cord and your branch circuit it's plugged into) should be sized as to prevent a voltage drop to 3% at the farthest outlet of power. Also keep in mind that would be for the total combined loads on that branch circuit.

    If that old circular saw that on start up or when binding is starting to smell funny and your plugged into a 100' 14awg extension cord on an old 15a circuit...... yeah, not good. That premature tool death will likely be due in some part to excessive voltage drop........

    I just googled voltage drop calculations and hijacked this since I almost always just upsize my conductors when I think it's an issue. Usually at around 180' (total branch length).........

    Quote Originally Posted by some web page
    Calculating Voltage Drop - 1 Phase
    I (Amperage - also known as Current)
    VD (Voltage Drop)
    R (Resistivity of wire - taken from NEC Chapter 9 Table
    L (Length of run - we typically calculate the drop per 1000 ft lengths)
    CM (Circular Mils of Wire - measure of the diameter (thickness) of the wire - again available from NEC tables)
    K (Resistivity Constant - 12 for Copper, 18 for Aluminum)
    Example (1) using VD = (2 * L * R * I) / 1000 ft
    Find the voltage drop on a # 6 THWN copper, 3 wire, 120/240 Volt, single phase feeder circuit of 150 foot length having a 60 A load.
    Use the formula above, and substitute the given values.
    VD = (2 * 150' * .491 * 60) / 1000' = 8.838 Volts
    The voltage drop is 8.838 Volts, we now have to check the % from the overall voltage.
    % = (VD / V) * 100
    Substituting values gives us: % = 8.838 Volts / 240 Volts = 0.0368 = 3.68 %
    This falls above the 3 % max. allowed, so you would check to see if you can use a # 4 THWN copper. (check NEC Chapter 9 Table 8 - Conductor Properties - column- ohm / kft = 0.30
    Do the same as the above example, substituting the resistivity value for # 4 copper, and if the VD falls under the permitted 3 % range then use it


    ---------- Post added at 02:58 PM ---------- Previous post was at 01:51 PM ----------

    So I was just out in the garage and checked one my better cords..... labeled SJTW 12/3. 400.4 Says it's under Junior hard service cord, 300v, can be 18-10awg, has a thermoplastic sheath, and is good for damn and wet locations.... and see note 15, which explains that the "W" designation is for outdoor use and suitable for use in wet locations and are sunlight resistant. The sunlight resistant part is new in the 2011 NEC....... there's lots and lots of new stuff in the 11' NEC..........
    mountain eagle
    longevity forcecut 50i
    miller econotig
    millermatic 185
    speedglas lid

  3. #13
    Member d4ve's Avatar
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    Mar 2011
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    Red Deer, Alberta, Canada
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    34
    There is quite a bit of good info in here. Almost worth a sticky.
    Equipment Used:
    - Miller Maxstar 200 Stick Machine
    - Hobart Stellar CC/CV
    - Victor O/A

  4. #14
    Quote Originally Posted by mountain eagle View Post
    Nope, the electrons don't care in the least............ solid, stranded, flesh......

    hahahaha... "FLESH"
    Ken's Welding
    Ken Harris
    Odessa,TX.
    432-349-0102

  5. #15
    How did this work out for bunk?
    Did he get it going well?

    I use abt 50ft of #12 extension for my 200p and it works well enough... haven't noticed any problem... but I'm not even trying to run high amperage or get close to the duty cycle.

    My old transformer boxes? That's a different story.
    If they don't get a good hot input feed, nothing good is gonna happen.

    ...the problem with solid conductors is the copper will work harden, become brittle, and break.
    ...The shielding on Romex type wire is just not up to the abrasion any drop cord will encounter.

    Far better to use proper equipment so you can concentrate on doing the best workmanship.

    Good luck
    rc
    Longevity Stickweld 140 Lunchbox Baby!
    Redi Arc & Craftsman AC boxes
    200P 3 in 1
    Harris gages/Victor & Smiths torches
    101.07301 project
    Large pile of saws & drills
    Wheel barrow full a sanders N' grinders
    truckloads of woodworking tools
    the paint pumps, ladders and stuff
    rock n mud tools & plumbin stuff
    Lapidary thangs
    mekanik tools
    & I am a pathological liar and functional illiterate.

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