Replies

1. 
   BG | Dec 16, 2002 04:45pm | #1

   Bo,

   They do have the short ones for dryers and stoves, however, your correct, I went searching a few weeks ago for one and came up empty(big box stores, hdwre stores).  I suspect there is little demand for them...

   I added extra length of 10/3 to act as an extension cord.  It is not very flexible however.

2. 
   bill_1010 | Dec 16, 2002 04:58pm | #2

   most 220 are custom applications since they all have different plug and amp requirements.

1. 
   HowardAcheson | Dec 16, 2002 08:07pm | #3

   I agree and want to point out that voltage is not the determinate of the size of the wire in a cord, the amperage is. In most cases, a 240 extension cord can be of less wire size than 120 volt but I would always use at least 12 AWG.

   Size the wire based on the 240 volt amperage rating of the motor (purchase 600 volt rated wire for its thicker insulation and covering), purchase the correct connectors and keep the wire no longer than necessary.

3. 
   booch | Dec 16, 2002 09:01pm | #4

   It is cheaper to make one yourself. Just go to the electrical supply house in your area and get some Essex or SOOW type of wire of the appropriate gauge.

   Voltage drop and amperage is pretty important and a general 14 ga 300 volt extension cord can't answer all of the screwy applications 220 volt dreams up. In answer to the question there are too many issues of safety and performance.

   I have one I made that is 30 foot with a 4x4 handy box on it. 1 duplex 120 volt and 1 - 240volt outlet are in the box. Currently it is hardwired to a GFI breaker but it will soon be moved to my shop for the same application. That is running the table saw, sander & planer outside on sunny days.

   After reading the posts above there are two other issues.

   One use stranded wire it is far more flexible. Use an extension type wire. SO, SOW, SOOW,etc. are types of Neoprene or rubber jacked stranded wire with a lay of stranded neoprene insulated wires including filler that rounds out the cord as well as provides moderate crush resistance. Get yellow cord rather than black as it sort of screams to people walking in the area, "hey watch out" plus some even have wear layers that show red when you've scratched off enough of the outer jacket.

   Two, The fittings need to match with the cord exterior OD so that the plug and receptical can grip the jacket and give proper strain relief. Take them with you when you get the cord. There is a standard OD for a gauge & conductor count but it depends on the rating/type of the jacket.

   
   

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   Edited 12/16/2002 1:10:10 PM ET by Booch

1. 
   Elcoholic | Dec 17, 2002 12:33am | #5

   I too have only seen ready made appliance cords.  They're designed for dryers, not really for portable use.  I set up my shop's 220 outlets and machines with 30A, 250V twist-locks (Nema L6-30).  I have a couple of 15' ext. cords I made up using 600V, #10 SO type cord.  The twist locks are spendy, but worth it IMHO.John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne

1. 
   booch | Dec 17, 2002 01:37am | #6

   Yep I put together an entire portable stage lighting set for my son's grade school out of 12 ga SO and twistlocks. I used twistlocks with different styles to circumvent miswiring. It also keeps you from kicking out the plugs. Kids have their feet on sideways you know....

   Putting a hook on the side of the dustbin under your table saw is a handy place to roll up the slack.

1. 
   HowardAcheson | Dec 17, 2002 02:13am | #7

   In prior discussions here, some folks knowledgable in electricity warned against coiling extension cords. It induces an electrical field which will cause heat and increased amperage.

   The outcome was that is it best just to have an extension only as long as necessary.

1. 
   booch | Dec 17, 2002 06:54am | #8

   Yes for the most part.

   But you don't generate much of a field with 2 or 3 loops of wire and the field generated is related to how tightly it is wound around the "core". On the whole If you have a 200 foot 30 amp cord it is a bad idea but on 15 amp 3 loops couldn't generate much of a voltage. I'm not going to worry but thanks for the tip."The time has come," the Walrus said, "To talk of many things: Of shoes--and ships-- and sealing wax--Of cabbages-- and kings, and why the sea is boiling hot-- and whether pigs have wings"

2. 
   TKanzler | Dec 17, 2002 06:39pm | #9

   If you've ever seen someone air-arcing (electric arc and compressed air used to dig out welds in steel) with a truck mounted welding machine, the two coiled leads hanging on the side of the truck (usually hundreds of feet) wiggle and move quite a bit as the arc is struck and broken.  This stuff is hundreds of amps DC, with the two leads coiled separately (two big electromagnets without the iron core).  Contrasted with a piece of SO cord, with both conductors twisted together in the same jacket, I would assume the opposed current in two conductors would tend to cancel magnetic and electric fields, for the most part, rendering the issue moot.  In my (possiby misinformed) opinion, for typical home- and small-shop, with intermittently loaded, hand-fed woodworking machines, a flexible extension cord of adequate gauge with good quality connectors, excess coiled as needed, is fine.  Along the lines of your post, isn't stage lighting virtually all done like that?  Scrap iron cranes use Reel-O-Matics to wind the (DC) magnet wire in and out while the crane is working, and vacuum cleaners have cord winders.  Keep in mind, my opinions are just that: my opinions.Be seeing you...

3. 
   Elcoholic | Dec 17, 2002 08:12pm | #10

   Low voltage + low current + a few coils + twisted conductors = no worries

   If there was a problem you wouldn't see those UL listed cord reels at the Big Orange Box right by the register for that "while you're at it impulse buy".  It akes lots of tightly wound windings to generate a field - there's probably a 1/4 mile of wire in a 1 hp motor.John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne

4. 
   BarryO | Dec 18, 2002 01:48am | #11

   "Contrasted with a piece of SO cord, with both conductors twisted together in the same jacket, I would assume the opposed current in two conductors would tend to cancel magnetic and electric fields, for the most part, rendering the issue moot."

   Yup.  The fields cancel each other out.  Especially with the low frequency involved (60 Hz); also, with the much lower current, compared to the arc welder wire.

   No need to worry about coiling extension cords, unless one is operating them near the current limit, in which case you may want to watch against bundling them too tight such that they don't get enough air circulation to cool properly.

5. 
   booch | Dec 18, 2002 03:34am | #12

   You are absolutely right. No issue here

   The field strength is relative to the square of the distance.

   Now high voltage is a different animal. I used to (highschool) trim for Asplundh tree Experts. We cleared power right of way with chainsaw, handsaw, and lopper. Warning issued to me on day 1 was to watch out for the single "fire alarm" wire found in old cities. It ran between poles and theoretically provided a separate alarm system for the fire department. The wire was strung on the power poles and often was run near the primary (5280 volts) The fact that the voltage was high, the wire was close, and it ran parallel for a couple blocks meant it could pick up voltage inductively. The danger was you'd be in a free climb and brush up on one of those and get the sense knocked out of you twice. Once by the voltage and the second when you hit the ground after falling from the tree.

   Tripping on too much wire or causing a fire by running solid conductors or too fine a gauge is the real issue.

   Stage lighting is heavy on extension cords. Often a set will have 100 to 200 for a big production for a city. Most cords have a peculiar 3 prong flat plug & receptical. The reason they wire with those plugs is a mystery to me. Twist locks are the way to go. Stage lights seem to derive technology from back in the 30's