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Wiring gauge

R

.research

Hi! Long time lurker (10ish years...wow its been a while), finally getting my own grow together and need a lil help.

Lil background first just for fun....

I have been planning on growing in a 4x4 tent in my bedroom for almost a month now and have been googling and searching like mad trying to negate any unpleasant surprises. Finally I'm ready to drop a few bucks to get started and then my roommate moved out and suddenly i have an insulated shed thats 10x12 with a 6 foot minimum ceiling available to me! SO... back to the drawing board, I might as well utilize the available space. I'm thinking about doing dual 600w doughnuts or maybe 315w CMH. I've got some auto seeds to get a quick harvest to replenish my stash, but then plan to start doing sativa leaning strains after I'm back into my comfort zone with respect to my bud levels.

My problem...

There's no power out to my shed so I'm gonna have to run an extension cord out there... I have plenty of 10ga extension cords and can run up to 3 out there on different circuits (really don't need that much power.... yet :biggrin:) I've always heard that running high amperage circuits like heaters or grow lights I suppose, is a bad idea on extension cords because of the power drop from the cord length. I'm pretty sure that most homes are wired with something smaller than 10ga (I don't really know but it seems like a place to save a buck when building a house).

My question...

Would it cause significant issues for me to run 1000w of power 50' on a 10ga extension cord for grow lights, pumps and fans?

I'm open to suggestions or critiques. Thanks to anyone who offers input.
 

GonjaLove

Member
I wouldn't do it. I had just a 1200 watt space heater going to my shed on a 50' extension cord and it got hot as shit. Only did that 2 days as I was afraid of fire. There was also a noticeable power drop on the heater. Wouldn't get near as warm as it did plugged straight into the wall. It's just not worth worrying about if it will work or not. Do it right and no worries :tiphat:
 

Ringodoggie

Well-known member
Premium user
I have heard the same thing about extension cords but I don't know how a 10g extension cord would be any different than running 10g Romex (or whatever outdoor equivalent they have).

I guess the idea situation would be to run line a few inches underground to the shed. Or, conduit.

One thing I did just think of. Not sure where you live but certain outdoor weather would degrade an extension cord rather quickly.

I'll say one thing for sure. The electrical is definitely NOT the place to skimp on your growroom design.

A small room is going to need 10 or 12 amps.
 
R

.research

I appreciate the answers guys, I think I can email a friend and kinda fudge the situation (he's a cannabis hater, and I haven't talked to him in years...), tell him its for a heater or something. If he responds I'll let y'all know his opinion is. I figure I'm probably going back to plan A and keeping a tent in my bedroom, or maybe plug a 1500w heater in to a 50 foot cord and stand around with a fire extinguisher and multimeter and see what happens. I doubt homeowners insurance will cover it if I burn this place down so safe is definitely the goal.
Thanks again guys
 

mowood3479

Active member
Veteran
U can get extension cords made for running generators in 8guage, prob 6 also..
run u like $100 for a 50'.. at least the one for my gen was about that much if I recall
 

Ringodoggie

Well-known member
Premium user
This isn't the best answer but it does give a fairly simple explanation.

If you are running an entire grow room, you definitely need to consider amp/watts/etc and use the proper gauge. If you were just running a light bulb 50' away it would be different. An entire grow room is a lot of amps.

https://www.thespruce.com/wire-size-underground-circuit-cable-length-1152899

This forum had some nice topics as well. This one hits home pretty close.... storge shed, 50' away. LOL

https://www.homesteadingtoday.com/threads/putting-electric-in-my-shed-what-size-wire.52094/
 

Ru5tyNaiL

Member
If your serious about growing, I'd install a dedicated 240v circuit in your main panel and run a sub panel off that to the shed so you can branch off and run 240v (lights) and 120v (everything else). Hardest part is the digging.

I know it's going to be fairly expensive, but its a lot cheap then having to upgrade again later down the road because you want to go bigger in the shed. I agree with the do it right the first time sentiment. It took me a lot of money and time to figure it out the hard way.
 

Yono Redux

New member
Extension cords are only for temporary use (30 days max). What you want is a 40 amp subpanel installed by an electrician. Call a couple out to get some quotes. Tell them you are putting an arc welder and/or air compressor in the shed.
 

St. Phatty

Active member
I needed a 120 yard extension cord to do some outside work.

Bought some larger single-strand copper wire from a friend who works at the scrap metal place for $8.

Then used some 18 gauge for most of the 100 yard run.

I spliced the single-strand and the 18 gauge into a power strip, so it still has the breaker.

BUT I'm only running a water pump - maybe 300 watts. Probably spending 50 watts heating up the wire.

For 1000 watts + ... definitely need some bigger wire - even for 50 feet.

I would also add ... you need to be at home for the first 24 hours of operation for a burn-in period. So you can walk around, feel the cords, see how copacetic everything is.
 

tleaf jr.

Came up off 75w
Veteran
10 gauge wire will not safely run a 1000w ballast .1000w ballast usually consume around 8.3 amps ran on 120v and half that ran on 240v. The safe size for that ampage is a 8wg wire which is rated for roughly 10 amps which will give you some wiggle room for fans pumps and controls :2cents:
 

Yono Redux

New member
10 gauge wire will not safely run a 1000w ballast .1000w ballast usually consume around 8.3 amps ran on 120v and half that ran on 240v. The safe size for that ampage is a 8wg wire which is rated for roughly 10 amps which will give you some wiggle room for fans pumps and controls
2cents.gif

Where do you get this info? 10awg is good for 30a intermittent use (under 3hrs) and 24a for continuous use.
 
R

.research

So general consensus is that this is a bad idea and I'm pretty much abandoning it (hunting season is here and I picked up a new scope and boots instead :biggrin:).

However according to this.......

https://www.icmag.com/ic/showpost.php?p=2265230&postcount=4

CMA Coefficients:
#14 AWG = 4110
#12 AWG = 6530
#10 AWG = 10380
#8 AWG = 16510
#6 AWG = 26240
#4 AWG = 41740
#3 AWG = 52620
#2 AWG = 66360
#1 AWG = 83690
1/0 AWG = 105600
2/0 AWG = 133100
3/0 AWG = 167800
4/0 AWG = 211600

K = 12.9 Constant for Copper

Voltage drop formula:
Ed = K x I x L x 2 / CMA

Diameter with respect to desired Ed:
CMA = K x I x L x 2 / Ed

CMA = 12.9 x 15 x 50 * 2 / (120*.025)

(120*.025) is 2.5% maximum voltage drop = 3 Volt drop

CMA = 6450

6450 CMA seems to indicate I can safely run this circuit with 12AWG wire and be quite safe at the 10AWG standard.

Then I was about to post and realized that L value is probably supposed to be measured from the breaker panel which means I probably should up my L value to 150. Its about 30 feet in a straight line so I figure 60 as the wire is routed is a very safe guess.

One more time...

CMA = K x I x L x 2 / Ed

CMA = 12.9 x 15 *110 * 2 / (120 * .025)

CMA = 14190

CMA of 14190 would mean: 3/0 wire

So I'm thinking that its probably a bad idea too. Anyway let me know if you think I have an error anywhere. I love to play with algebra stoned but I know it makes me significantly more error prone :smoke:
 
R

.research

By the way... thank you to Phillthy and madpenguin for the formulas and information
 

Badfishy1

Active member
10 gauge is rated for 30 amps. You have a problem somewhere in your voltage drop equation ( can't be bothered honestly to figure it out). I will say at the moment on a project I am working on, I am running a 30a Temporary AC unit on a full spool of 10/2 Romex and there is absolutely NO problems. (Yes I am a licensed electrician)
 

Badfishy1

Active member
10 gauge wire will not safely run a 1000w ballast .1000w ballast usually consume around 8.3 amps ran on 120v and half that ran on 240v. The safe size for that ampage is a 8wg wire which is rated for roughly 10 amps which will give you some wiggle room for fans pumps and controls :2cents:

Sorry bud, you are 100% incorrect on not being able to run 1000w on 10 gauge wire. I have service contracts on a sub development that runs streetlights on 30a circuits over a half mile in length all ran on 10 wire. Each ballast is 250w and most circuits have 20 ballasts on them. 250*20= 5kw 5000/240= 20amps well within the 80% tolerance of circuit load
 
G

Guest

Buy an "Ugly's" book. Nema codes not stoner science.

http://www.uglys.net/

About $15 or less and once you have one you will never have to rely on someone who doesnt know shit but thinks they do.
 
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