dslreports logo
site
 
    All Forums Hot Topics Gallery
spc

spacer




how-to block ads


Search Topic:
uniqs
31679
share rss forum feed


whizkid3
Premium,MVM
join:2002-02-21
Queens, NY
kudos:9
reply to fireflier

Re: 150' Extension Cord

beeron and fireflier have basically nailed it. The voltage drop is twice that of the length of the cord, and has some reactive impedance drop, as well. The impedance is relatively small for resistive loads over SO-type rubber cords - a lot more for wiring in conduits and reactive loads.

For a 20 amp load at 120V, single phase; 50 feet is about the maximum you can run on 12 AWG without exceeding the NECs maximum (3%) on branch circuits. And you have yet to include the voltage drop within the branch circuit wiring within the building (which could already be up to or over 3%), and any drop on the feeders. So, before you even plug in the extension cord, you could already be down a total of 5% from nominal voltage.

The main point to remember is that to size the extension cord's gauge properly, you have to consider the current draw (and possibly power factor) of the load(s). I would recommend 10 AWG minimum to be a decent 150' long extension cord that can handle a variety of power tools.


Splitpair
Premium
join:2000-07-29
Cow Towne
kudos:3

1 recommendation

reply to rudnicke
said by rudnicke:

I only have outside power in my detached garage. I use it to run a leaf blower and lawn dethatcher about 130 feet from the garage.
Without knowing what those tools draw it's hard to say exactally how to do this but you might want to consider a heavy gauge 100 foot cord and connect it ot a lighter gauge cord say 25 feet or so to give you an easy to drag around cord. That way you could work an area and then pull the heavy gauge heavy weight 100 foot cord closer to where you need it vs. having to drag it around all the time.

Wayne
--
If you cannot fix it with a buttset and some beanies you ain't a technician.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8

1 recommendation

reply to whizkid3
said by whizkid3:

The main point to remember is that to size the extension cord's gauge properly, you have to consider the current draw (and possibly power factor) of the load(s). I would recommend 10 AWG minimum to be a decent 150' long extension cord that can handle a variety of power tools.
I have a different rule that I use for sizing extention cords...if you can carry it around conveniently, it just aiin't sufficient.


--
A is A


aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1
Reviews:
·Frontier Communi..
reply to Splitpair
said by Splitpair:

Without knowing what those tools draw it's hard to say exactally how to do this but you might want to consider a heavy gauge 100 foot cord and connect
I can use a table saw or a sliding compound miter saw. and a 300W halogen light on a 14 gauge 100ft cable. I can see the light dim when I use the saw, but they work just fine. I guess the combined load doesn't exceed 10A in my case.


miscnick

@verizon.net
reply to rudnicke


Y'all can argue till the cows come home (I hope that suits the mentality in this thread).....BUT.....

Take 150 ft of ANY gauge extension cord, plug it into a socket, plug ANYTHING else into the other end, and see how well it works.

Not one person has acknowledged that there is capacitance and inductance to figure in.
You do understand what those are....right ?

You can do all the Ohms law math in the world....but untill you plug something in and try to use it...it's all meaningless.

Buy the cord.
Use it.
Take it back the next day after spinning your wheels trying to figure out why nothing works on the business end of it.


Hydraglass
Premium
join:2002-05-08
Kingston, ON
He has this one right on the head - the load is going to make all the difference - I have 2 motorized tools that I use outside, far from my house, regularly - my 13A circular saw, and a 1.25HP air compressor rated at 10A - theoretically the circular saw should be the harder item to use on an extension cord, but in reality I have zero problems doing an entire day's work with it - cutting through PTL 2x8 and 2x10 boards - at the end of TWO 100 foot 14 gauge extension cords (mind you the 20A outside outlet I plug into is only 3 feet from my breaker box - so there's really no wiring loss to that point) - the compressor won't even start at 200 feet, and struggles at the end of just 100 feet right at first when the motor is still presenting it's start-up load. Luckily I have a long air hose, so I often just leave the compressor at the end of a 50 foot cord and reel out 100 feet of air hose.

So all the talk in the world won't solve the question - 10 gauge extension cord is overkill for anything under 250 feet - 12 gauge is fine in the 100-200 foot range for absolutely anything you might want to do - and 14 gauge is fine for 95% of the things you'll do inside 100 feet -- but everyone's situation is different. I can run my hedge trimmer or my leaf blower 300 feet from the house at the end of 2 100 foot 14's and a 100 foot 12 and they operate just fine - as neither is more than about 4A. If I was making for myself a 150 foot or 200 foot cord, or looking to buy one, I'd aim for 12 gauge however.

Uncle Duke

join:2008-08-21
Akron, OH
I've been able to find 100' and 50' extra heavy duty extension cords (10 ga) and bulk cable (10/3) at Home Despot made by Ridgid Tool, although am somewhat reluctant to try putting them together to run a blower on my coal forge (I have an artisian blacksmith shop in my backyard). The forge has a 1.5 A motor with what I believe is a 14 ga. electrical extension cord wired into the motor (a friend of mine did this when he bought the motor). Any concerns about the fan overheating/burning out or tripping/burning out the circuit breaker on the service panel when running? Should I replace the cord on the fan with a heavier gauge, or doesn't this really matter?


davidg
Good Bye My Friend
Premium,MVM
join:2002-06-15
none
if the motor only draws 1.5A the 14g is probably ok. turn the motor on and let it run for a few minutes. grab the cord and see if it is getting hot. if just a little warm, then the cord is fine. if uncomfortable to hold, then you need a bigger cord.
--
Lack of Preparation on YOUR Part does NOT Constitute an Emergency on Mine!


cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to miscnick
said by miscnick :

Not one person has acknowledged that there is capacitance and inductance to figure in.
You do understand what those are....right ?
Since you seem to know about them (and throw them in), maybe you can come up with actual numbers... or not
And since you seem to have heard about them, remember it's 60Hz not 600kHz. While they do exist, their effect is so low that it can be neglected.
I use an electric bush trimmer with 4 x 50' extension cords in series and it works just fine


EGeezer
Premium
join:2002-08-04
Midwest
kudos:8
Reviews:
·Callcentric

1 edit
reply to miscnick
said by miscnick :

Y'all can argue till the cows come home (I hope that suits the mentality in this thread).....BUT.....

Not one person has acknowledged that there is capacitance and inductance to figure in.
You do understand what those are....right ?
There may be bovine mentality in some discourse, but not in that of beeron, fireflier and Whizkid. Those who considered PF/ VI*(Cos ) did indeed factor in capacitive and inductive reactance. IIRC, a rule of thumb for the Power Factor of most small motors is 0.7. The basic rule for a closed circuit is that power of source and power of all loads is equal, but voltages and currents at any given time can vary with the lag and lead of amperage and voltage depending on the capacitive or inductive reactance of the node. In the case of the extension cords, they're almost pure resistive loads while a motor could be capacitive on startup, but reactive inductive in running state. As the motor load increases, the phase differential between armature and field could be greater, resulting in a greater inductive load.

One could also consider the internal impedance of the source, which can generally be visualized as a voltage source with a resistance load in series with one pole, and the circuit's load nodes being capacitors or inductor coils in series with the resistors. In this case, though, I'd consider the source resistance and impedance to be negligible if the source is the main distribution box.

It's been awhile since I crunched basic AC power circuits, so I hope any active power engineers correct any misstatements I may have made.
--
The greatest dangers to liberty lurk in insidious encroachment by men of zeal, well-meaning but without understanding. -- Justice Louis D. Brandeis