Electrical For Your Indoor Garden
By: David Stern
Everybody wants a well-lit, climate-controlled, beautiful indoor garden in their home. But do you have enough power? And how much is it going to cost to run this garden? And if you don’t have the power, how would you add more? In this article, we’re going to be talking electrical for your indoor garden.
“But wait, aren’t you just like some gardener on YouTube? What do you know about electricity?”
Well, yeah, I am a professional gardener, but I am also a licensed Master Electrician here in the state of Illinois. With that said, I know a thing or two. Let’s dive right in.
Lighting: Electrical for Your Indoor Garden
As you may know, the technology behind lighting and especially grow lighting has evolved dramatically over the last decade. Because of these improvements, the power requirements for an indoor garden have come down to much more comfortable levels. The high pressure sodium and metal halide lights of the past were so inefficient that about 80% of their consumed energy was used to create heat, while only 20% of the energy it used was creating… light.
Modern LED lights have flipped that ratio around, now using 80% or more of the energy consumption creating light. Because the lights generate less heat, you also enjoy less cost in cooling and venting your space. That means from here on out, I’m only going to be talking about LED lighting since that’s the only acceptable form of lighting at this point. (Sorry, I know that’s going to offend some people.) To dive a little deeper, I made this short video. I highly suggest checking it out.
If you’re looking for a fantastic starter grow light, check out this HLG 250 VEG PRO. I’ve been using HLG lights myself for years, they are great quality lights and at a good price.
Grow Tents: Electrical for Your Indoor Garden
If you’re just getting started, two popular configurations for an indoor garden are the 4×4 ft. tent and the 4×8 ft. tent. This is what you see in our videos. This VivoSun 4’x8′ and this AC Infinity 4’x4′ are both great choices.
Electrical:
The 4’x4′ comes with a 400-watt light, a 6-inch inline exhaust fan, and a controller for environmental control. Plus, we added a couple of clip-on fans. When added all together, the total power consumption of this complete setup is about 457 watts. However, if you have any electrical load that is run for more than three hours continuously, you need to adjust that up 25%, according to the National Electric Code. So, this garden is a basically now a 571 Watt garden.
The 4’x8′ kit by VivoSun is equipped with four 200-watt lights, an 8-inch inline duct fan, and a controller. We’re going to go ahead and add 2 clip-on fans from the Vivo Sun website, and a tower fan to this. (Because honestly, this kit is inadequate the way it comes.) Add it all up, and that comes to a total of 957 watts or 1191 properly adjusted. With this total wattage, we can then divide that number by our voltage, 120v in our case.
“Well hold on, I thought I was supposed to use like 240 volts for all this stuff.”
Nope, that’s not the case. Larger indoor gardens with many lights can’t see the benefit of having higher voltage lighting circuits, and we’ll get to that shortly. On that note, small gardens will see no noticeable difference in energy cost.
Calculations: Electrical for Your Indoor Garden
We take the wattage (1191w) divided by our voltage (120v), and now we have amps (9.9A). This is now the final number we need to properly determine our electrical requirements. The 4’x8′ tent uses 9.9 amps, while the 4’x4′ uses only 4.7 amps. Considering that your standard bedroom circuit has wire and a breaker rated to carry up to 15 amps, you can plug a 4’x4′ tent into any outlet in the house. The 4’x8′ tent, on the other hand, is a slightly different story. Yes, it’s true that a standard 15 amp circuit can power a 9.9 amp grow tent. However, that leaves very little room for any add-ons like pumps, side lighting, or perhaps a small space heater. Also, if that circuit is being used by anything else, the breaker may trip, leaving your garden dark. No good.
“Whoa, are you saying that this 4’x8′ tent only uses 957 watts to run? And if I had the lights on for 18 hours a day, I take the product of those two numbers, divide it by 1000, and then multiply that by my standard utility rate to get $2.75 a day to run?”
Yes, that’s correct. The total cost here in Illinois to run this garden is only about $2.75 per day. You can figure out your electrical utility rate by taking the total cost of your bill, then dividing that by your total usage. This will give you the actual price you pay, including taxes and fees. For us, that comes to $0.16 per kWh.
Now let’s get back to that 9.9 amps. Here in our basement, we have a pre-existing 20 amp circuit. However, other appliances are using that circuit. So, what do we do? We add an additional 20 amp circuit directly into our garden. This circuit goes from the panel to a timer, and finishes with a quad-style outlet box mounted to the ceiling of our tent. This box will be used for anything that requires a timer, such as lights and maybe a couple of fans. Everything else can be plugged into a power strip here on the floor, which runs outside the tent to that preexisting circuit we mentioned earlier.
Labor: Electrical for Your Indoor Garden
Now, I want to talk about exactly how I added that circuit into this garden, but first a quick disclaimer warning: All electrical for indoor gardening should be done by a licensed electrical.
***This is educational information intended for students, apprentices, and licensed electricians. Do not ever attempt for any reason…ever. ***
I chose to install a 20amp circuit in this garden. The material did cost a little bit more, but it was worth it in the end. Let’s start with the breaker. This subpanel accepts only Square D brand QO style Breakers, so that’s what we installed. You can check your Breakers for brand or model number, or just compare them to these Standard Breakers shown here. After the breaker, you’ll need some wire for a 20amp circuit. 12 gauge wire is standard. Do not use 14 gauge, that would be a fire risk. Technically you could use 10 gauge wire, but it’s a lot more expensive and not necessary for wire runs under 120 feet.
Getting Power To The Indoor Garden – Electrical for Your Indoor Garden
Next, we need a plan for getting power from the panel to the garden. Considering the grow tent is a temporary structure with soft walls, you don’t need to install conduit or even Romex. Realistically, your goal is just to create a high-quality extension cord. That’s it. And for this, SO cable is the perfect choice. SO cable is made of many thin wires, allowing it to bend easily without breaking. We bought this 12/3 SO cable from Home Depot, so it’s pretty easy to find. We connect the green wire to the ground bar, the white wire to the neutral bar, and the black wire to the breaker. Please note that this is a sub-panel we are working with, so the ground in the neutral bar is separate. If this was our main panel, the grounds in the neutrals would be connected to the same bar.
We turn on the breaker, which sends power to our timer, which controls the outlet box. Because we mounted this box to the ceiling, the cords from the light don’t need to hang down. Going up from there, if you’re planning on building a large commercial-style grill, as mentioned earlier, it is a good idea to run your lighting circuits at higher voltages such as 240v, 277v, or 480v. The benefit of this is only seen during the construction stage, as higher voltages mean lower amps, which means less wire. Yep, that’s it, less wire is needed for higher voltages. There are some minute efficiency gains when you run LED drivers and higher voltages. However, the cost savings you’ll see are, like I said, minute.
Electrical for Indoor Garden – Conclusion:
We’ve covered a lot of information in this article and I’m sure you have some questions. Hopefully now you understand a bit more about electrical for your indoor garden. Check out the video below, as it may be helpful, and ask any questions you have in the comment section below. We’re here to help.
For more free gardening education, check the rest of our website and our YouTube channel. We are your trusted gardening supply source and our online store has everything you need, tested and ethically sourced by us personally.
Until then, never stop growing!
Video:
Electrical for Indoor Garden