Question regardind wire size please :)

[il19z8rn4li1]

Hello friends.

Ran into an opportunity to where i can have a decent sized
LED grow op, but the issue is getting power to the location.


I need to run a wire under ground in conduit about... 300-325 feet.

Ill be running roughly 2000 watters of lighting.
500 watts of AC
400 watts of FANs
and maybe another 250 watts miscellaneous

so thats 3150, lets round that up to 3200 then figure out what
that is 80% of...

3200 / 80% = 3937.5 watts.

Lets round that up again to 4100 watts is roughly the TOTAL
wattage i need.


What my concerns are is the more detailed math involved in this calculation, namely the voltage drop on such a far run... 300+ feet.


So what i ask of the electrical gurus at this amazing place is this.

With what info I have given, can anyone that deals with this stuff
on the daily over look this for me and give me what kinda wire ill
need to purchase for this adventure


Thanks so much.

 

[Guest101]

For starters, code requires that we run only one feed to a detached structure. This can and should be a three wire feed with both phases, neutral and of course ground.

You would set a subpanel and install breakers, one for lighting at 240v and the other feeds at 120v.

One should drive a grounding electrode and run to the subpanel using #6 bare copper.

Do not install green bonding screw as this is a subpanel not a service entry.

So im doing math based on giving you a 30 amp subpanel in your detached structure.

Using #2 aluminum or #4 copper will limit your vdrop to less than 3 volts. I recommend this option.

 

[il19z8rn4li1]

For starters, code requires that we run only one feed to a detached structure. This can and should be a three wire feed with both phases, neutral and of course ground.

You would set a subpanel and install breakers, one for lighting at 240v and the other feeds at 120v.

One should drive a grounding electrode and run to the subpanel using #6 bare copper.

Do not install green bonding screw as this is a subpanel not a service entry.

So im doing math based on giving you a 30 amp subpanel in your detached structure.

Using #2 aluminum or #4 copper will limit your vdrop to less than 3 volts. I recommend this option.

none of that helped me to well. Sry but I need a lil more detail then that my friend.

 

[Guest101]

none of that helped me to well. Sry but I need a lil more detail then that my friend.

What detail did I miss?

 

[il19z8rn4li1]

sry, lol im just used to Rives replying to any electrical questions, so excuse me if he spoiled most of us that know him as a pretty seris electrical guru


He usually posts charts and graphs and what not something for the questioner to review
and read up on him/herself.


YOu know, kinda actually "LEARN" why to do the electrical "such a way" instead of being
just "told" how to do it....

get what im saying??? lol


Im not the kinda guy that just asks how to do something, id like to know WHY ITS done
that why ...etc... etc...
and id like to do some reading regarding it.


So mainly... if you can post up any literature i can review regarding such a task
that would be great.


I did a bit of researching myself of course, its just I know that people that deal
with electrical for a living, kinda just, "got links on hand" lol



Dont take my text the wrong way... im happy you posted something my friend,
something always better than nothing




not judging, because I dont have anything from which to JUDGE, but all i got to support your text
is your recent join date and that your user name is a website, for "advertising purposes", maybe?
From that, i simply can logically assume that you know more specifically about how to grow MJ
rather then wiring "semi-industrial" electrical over a rather LARGE DISTANCE.

JUST SAYING lol dont hold that against me please lol I can infer with what I have to infer with...
for as little as I know, you COULD very well be a trained professional electrician, which then
in my case would be useful to know hehe

 

[Guest101]

Search google for voltage drop calculator or formula. There is plenty there. I'm typing on a phone. Sorry for the lack of charts and graphs. Lol

 

[il19z8rn4li1]

Search google for voltage drop calculator or formula. There is plenty there. I'm typing on a phone. Sorry for the lack of charts and graphs. Lol

HEHEH, ya my desktop took a shit the other week... FML lol
if its not one thing its a god damn another.. lol

So im limited to my phone as well, but the TALK TO SPEECH
works pretty damn well, so makes for decent foruming, just gotta
go back and fix some minor grammar shit and wrong words.



I have been through google a bunch....I have been getting a bunch of different wire styles and combos.


I guess, what i needa know is how it can be 100% safe
and to code. Money isnt an option.

Im already expecting this to cost around 3grand just to get power
out there. Thats no biggy though.


thanks for the input though, ill be sure to do some more research
and do some more reading for sure in the meantime while i wait
for some more replies hopefully





I guess what I need to really figure out, is what I haev available
to me in my location regarding what kind of wire I can get my
hands on... thats is something I have read on other forums.




MY buddy just installed NEW feed line from teh street to his house.
House had the old solid strand 2 wire copper that was only 120volt and overhead.

He installed some aluminum 3 wire cable inside conduit under ground
and I was thinking, i might be able to just go through his same guy
to get that same wire....

I mean since I know i wont be running at all near 200 amps which
is what is being fed to his house from the street.


ill only be maxing at around 18amps... and thats is 100% EVERYTHING is running, which will NEVER HAPPEN.




Just trying to wrap my head around these LARGER wire calculations
that regard DISTANCE and also regard either being OPEN AIR or
being ran through conduit.

I wanna have a good understanding of this stuff because within next 5-10 years Ill be purchasing some land and be living 100%
off grid with my own solar and wind energy. Im already food
sustainable, just needa get the LARGE LAND now lol

this will be very useful knowledge for me in the future, so might as well get a decent grip onto it now, because Ill never hire anyone to anything that I know i can do myself with a lil diligent research...

know what i mean vern

 

[Guest101]

One determines how much power to pull. Then a vdrop calculation determines proper wire gauge to use for the distance run.

so for a 30 amp 240v feed we need #10 copper normally. Go up to 325 ft and to keep vdrop below 3% we need #2 al or #4 copper.

Buried, buried in conduit or overhead makes a difference. http://www.southwire.com/support/voltage-drop-calculator.htm

Run your own numbers and find a happy medium. Perhaps a 20 amp feed.

 

[tokersmoke]

Okay im no electrician.I ran three twenty amp circuits 250ft away from an outdoor power pole.Ran 12 gauge wire through pvc drinking pipe and into the ground 8inch.Ran wire and outlets bam!!figure out the amperage and go from there.Everything is smooth so far.Total cost was under 400.Im sure it will last.IM no electrician and im sure someone will point out something unsafe.I feel better then running extension cords!!

 

[sourpuss]

The first response is what u should do. Regardless of how he told u.

U can do it many ways but u asked for low voltage drops and he gave it to you. First u say 4000 watts. Then its 18 amps..

Do it right. Dont skimp. Especially with electrical

 

[rives]

I appreciate the kind words, il19!

GrowersRUs did a very good job of outlining what you are going to need and what you are getting into. You will have to determine what your actual needs are, but his punch list works well for a 30a feed. If you are planning on running up to 18 amps on a continuous basis (3+ hours = continuous in this case), a 30a feed is necessary because of the 80% rule - if you think that you will be staying under 16a, then you could use a 20a feed and drop the wire size some, but it will really only drop you one wire size (from a #4 to a #6 in copper). You don't want to do it twice, and most of us wind up adding more load as time goes on.

Tokersmoke, no, you aren't an electrician. Assuming you ran 120v, at full load current 250' on #12 wire will give you a voltage drop of 16.5%. The maximum for residential usage is 5% and I prefer to stay under 3%, particularly if you don't want HID lights dropping off line every time a light switch gets flipped. It is better than extension cords, but still leaves a lot to be desired.

 

[tokersmoke]

Rives been working for weeks!!

 

[rives]

Rives been working for weeks!!

I didn't say that it wouldn't function, just that it wouldn't function the way that it should. If the circuits are lightly loaded, you can get away with too small of wire a little better - as the current goes up, the voltage drop increases. The voltage drop then makes the current go up even more on devices that are designed to have a fixed output, which further exacerbates the problem. Motor loads in particular really don't like low voltage - lights are a little more forgiving. If you are running HID lamps, I would be willing to bet that they are dropping off line and having to restart far more frequently than they would if the circuit was designed properly.

 

[CmdrAppleton]

I'm imagining NM-B pulled thru white pvc. Lets at least hope he used thwn. I've rarely seen a buried conduit that wasn't full of water at some point.

 

[il19z8rn4li1]

Hells yea, thanks Rives and ....the guy with the website username lol

 

[il19z8rn4li1]

Ok I found this link so far for the wire.

http://www.wireandcabletogo.com/4-3C-THHN-PVC-Tray-Cable-with-Ground.html

this is the correct wire ill need right? from what i read, it seems to be up to par.

 

[rives]

That looks like it would work fine, but if you are in conduit it would probably be cheaper to buy single-conductor #4 THHN and pull four of them into the pipe. #4 comes in multiple colors, or you can use phase tape to indicate ground, neutral, etc.

 

[il19z8rn4li1]

I was thinking about that way too, just wasn't sure wat would be better, if there is even a difference.


Found this site also.


http://www.electrician2.com/calculators/elcal.html

 

[rives]

Functionally, there would be no difference. However, the cable that you found is a multi-conductor cable rated for direct burial, so all of the individual wires are tightly bundled together within an outer jacket. This makes it more difficult to pull into a conduit because the wires need to change length as they go around corners - the ones on the outside of the bend need to get longer, and the ones on the inside get a bit shorter. If you are pulling individual wires in, this slippage is accomplished with little effort. It is harder to pull a large mulitconductor cable into conduit.

Also, individual wires with THHN insulation have a mylar outer jacket that is very slick, which also contributes to the ease of getting them into the pipe.

The cable is a bit more expensive, but is made to save you the cost of buying & installing conduit. The cost isn't totally negated, though, because it needs to be deeper (usually 18" dependent on local regs, and some places don't allow direct burial), and it should be "bedded" in sand or screened material to keep sharp rocks from getting against it.

 

[il19z8rn4li1]

Thanks Rives Help me out a lot brohan, much appreciated.

Ok, just spent the last hour looking over all the stuff im buying that
consumes power.

This is what we got finalized.


- Flower area -
1440 watts at 240v
400 watts at 120v


- Veg Area -
578 watts at 120v


- Lung Room/Work are -
269 watts at 120v
515 watts at 115v (AC)


So totals are
1440 watts at 240v (lights)
1247 watts at 120v (fans and accessories)
515 watts at 115v (AC)




-amps-
6
10.39
4.47

20.86 amps total if everything is running at same time at their rated voltage...
did i do that math correctly??
(also, the flower wattage is split between 2 tents, so only half will be
on at a time.)

I wanna add 3 amps for a little expansion.
I'd also like to know how to figure out what would be around the MAX load
on the cable that is #4.





so now I consider the 80% rule so...

23.86 / .80 = 29.825 amps required for safe operation, no?


how things looking now?

From the calculators I used on that site, I believe things still look good.