Figuring out about watts on lighting

@dbrn32 @MattyBear @Mark0427 @Ickey @AfgVet

Hello everyone I am hoping someone could help.

I am trying to figure out about lights and watts.

My first few grows I have used 2 “KING LED” brand lights one light was 1500 watt and the other was 3000 watts. The 4500 watts was running in my one room off the 120volt outlet. This does not include the one 12-inch carbon filter. Also inside the tent was my 8-inch carbon filter. This was all I ran off my outlets in that room. I did not have any trouble with the breaker or GFI popping causing the lights and everything that was running off that outlet to turn off.

NOW… I want to upgrade to better quality lights like HLG. I am wondering if i use the better quality lights, will the HLG watts pop my breaker because it is a better quality light? I am not sure if the 2 KING LED lights wasn’t really pulling 4500 watts because they were not quality lights.

Maybe the 4500 watt KING LED lights were not actually pulling 4500 watts like the specs say it is?

Maybe they were only pulling a total of 500 watts that’s why i had no breaker issues?

Do you think a 600 watt HLG light will pull more watts from the 120volt outlet since it’s a better quality light ?

It says that a home outlet can pull maximum 1800 watts from the 120 volt outlet. But again i was running more than that from an outlet with the KING LED’s with no turning off issues.

I want to buy 3 new quality brand lights like HLG to run my 2 tents. I have a 4x8 foot and a 5x5 tent for flowering. 2 lights for the 4x8 tent and 1 light for the 5x5 tent.

I appreciate everyone here that has helped me throughout my grow your feedback and information was very helpful. I hope someone can shed some light on this topic.

Have a great day and stay Stoney!!


High efficiency LEDs like Samsung’s LM301 diodes in the HLG models will deliver more light for less watts. There should be no issues with your breaker.

Correct. These burple lights generally only draw 10% of what they state the wattage is. The “4000 watt” draws ~400 watts, the “3000 watt” draws ~300 watts, and so on. The real downside with the burple lights is that more of that wattage goes toward generating heat than light since the diodes they use are far less efficient.

It’s different with HLG lights since they don’t misrepresent their lighting capabilities. A 260 watt HLG will pull 260 watts.


Thanks for the response. So if I decide to use HLG I am thinking of using 2 lights for my 4x8ft tent and 1 for my 5x5 tent all for flowering. What HLG should I go with that will be best for these tents to give me maximum coverage?

I am trying to stay away from having to use an electrician. I do know of a electrician however it is hard for me to get him to come over to wire my room so i can safely use more watts.

Thanks again for the reply Midwestguy!!


I am not familiar with all of HLG’s products. Dbrn would be the best person to address which light gives the best coverage for your grow space. I will say that you will want ~40 watts per square foot of canopy.


With the latest models of HLG lights this number can be reduced to 30 watts per square foot.

Like stated by @MidwestGuy these ‘blurple’ lights are misleading and you are without a doubt running far less than is quoted by the manufacturer. More efficient diodes means more output per watt consumed. Due to the spectrum of the lights, less actual power is needed to deliver the correct amount of light.

If you can afford it; get more light than you need then run the lights at a lower power setting which will further increase efficiency.

I built my own lights from early Samsung EB strips. At peak I’m running 200 watts actual per plant covering a 2 X 4 footprint times four. On one 10 amp breaker I’m running all of my lights, fans, pumps and exhaust fans. Never popped a breaker.


Just so you know.
I looked up your lights on kingledlights. The king plus 1500 consumes 260W. The king plus 3000 consumes 615w. Both use Epistar LEDs (no idea which ones). The 3000’s color spectrum test report showed it drew only 508w.


@shaggy808: I am presently running a HLG 350R in a 5x5, and it is enough for veg, but I will need to just about double this when I flip the time to flower cycle.Since you say you are going to buy three new lights. I would recommend starting with three 350Rs; two in the 4x8, one in the 5x5. Then when you get to the flower cycle you can supplement the tents with your existing lights. This way you can minimize you investment while you are finding out what way works best for you.
As far as the load on your electrical circuits go. I would recommend that you use one of those plug in watt meters, (Kill A Watt is one brand). Use the meter to read the total of the current load in watts, on each circuit breaker. For a 120 volt 20 amp circuit, 2400 watts is the max, and you should limit the load to about 2000 watts. For a 120 volt 15 amp circuit, max is 1800 watts, and you should limit the load to 1500 watts. If you load a breaker up to 100% current capacity it will cause an early death of the breaker.


Yes, this is the reason. The specs listed by others are probably pretty accurate. If nothing else, products sold in US should have label or tag somewhere or on cord. Listing volts, amps, and frequency. Volts x Amps=watts, so if label says 120vac and 2.1A, 120 x 2.1= 252 watts.

The proper lights to use for this aren’t going to safely run on the same circuit. You can probably run the 5x5 on one 20 amp circuit as long as not planning to run a dehumidifier or anything with large power consumption in it. The 4x8 is probably going to need it’s own 20 amp circuit for lights and another 15-20 amp circuit for support equipment. The led drivers act like electric motors when started. They pull a short burst of power much higher than they run at when turned on, so most manufacturers recommend 1 large driver per 120v circuit or 2-3 small drivers per 120v circuit. Looking at size of your tents, you’re going to be in large driver range.

Also wondering why you want to use the smaller space for flowering and larger space for veg? Most of us do this other way around as 1 plant halfway through flower typically takes up more space than the same plant did earlier in it’s veg state. What you decide here we can figure out.


Participation in this topic can become expensive. The Kil-a-watt meter will show circuit loading of all equipment, momentarily totals, as well as individually. The LUX meter (android phone not sufficient for the truest measurements and support software) will give LUX numbers for conversion to PPFD, DLI, PAR and more fun than imaginable. I map the crown for each plant and decide will she be happy.

As for the lights. I bought my first light in 1973, and better lights in 1980 and 1983, as “better” lighting was available commercially. I started buying lights again in 2013 and since. Vipar Spectras were the easy to buy and being un attached to the forum, I bought a few. Spares are important in many events.
The HLG 350 R (purchased last month), uses less electricity (345W) than the Vipar Spectra V1200 (555W) and out produces the light significantly with noticably less heat from light drivers. The two do fill my 4x4. The lung room runs 1700Watts (15Amp circuits, currently), and then the wife wants to do laundry.

1 Like

So you know, breakers are not meant to be ran to 100%, in fact the national electric code states that they are sized to not exceed 80% of the rating. There is 100% rated breakers, but they are not in houses generally and used for power distribution on a industrial level. This is why there is problems with the standard duplex receptacle circuits bc no1 can plan on how much a home owner will plug in. One weak link in the chain like a poor connection, with breaker and wire maxed out could start a fire if breaker was just shy of tripping. Dedicated circuits is a must. Even worse, people using 18 awg extension cords tied into a 20a rated circuit is a recipe for disaster. Please use caution. 20 yr union electrician journeyman.


actually, I am trying to use both tents for flowering> For my veg I was going to use another tent or room in my house. Still trying to figure it out. But I would hope to use my 2 tents now for flowering.

Thanks for the help! Have a good day

1 Like

Okay sounds good I will get a plug-in meter for sure. Now with the HLG 350R can i use those for flowering or just veg? I was hoping to still use the KING LED for the Veg in another room, when they are ready to be flipped i was going to transfer into the 5x5 and the 4x8 tent to flower.

Thanks Ickey for the reply much appreciated!

thank you for looking that up. Wow I guess that’s why I had no breaker issues because it was not drawing much from the outlet. thanks for the help breadless have a good day

@Poseidon1 @Ickey @Myfriendis410 @MidwestGuy @beardless @DEEPDIVERDAVE @dbrn32

Okay so I guess if I get a much better-quality higher-powered lights, I should wire the rooms correctly I think would be my smarter choice. One thing is I am not sure how to find an electrician that would do this work.
I really don’t want anyone to know what I am doing. Trying to be discreet as best as I can.

Any ideas on how I could go abouts finding an electrician to wire my rooms appropriately and safely?

What would I say to the electrician? I can’t assume I would say " Hi I am trying to grow a ton of herb can you wire me up" LOL.

These HLG or whatever better-quality lights I choose will be for my 4x8 and 5x5 tents for the flowering stage. I wanted to still use the KINGLED’s for its early veg state in another room like my master closet.
Would this be okay to still use the KINGLED for veg, then transfer them into the 4x8 and 5x5 tent for its flowering stage? I am trying to have a cycle, when the flowers are ready to harvest the Veg in the closet would be ready to be moved into the flowering tents.

I really do appreciate everyone’s feedback and help on this topic you guys are great!

Both, DLI considerations and tent area available. I would love two 350Rs for a 4x4 or 5x5 tent.
I bought a book, years ago. Then E=IRR came to being. Genie in bottle works better than when smoke appears.

1 Like

Mind if I ask what does DLI and E=IRR mean?

Yes, I am a believer.
Third house re-wire or new wiring project, 6/2023. After Disney and
grow sabbatical until 8/2023 with the New Roof and Solar Panels, too, I hope.

DLI forum search for Daily light I.

E=IRR is the formula for voltage. Electricity is the result of Current crossing resistance (resistance is RR or RSquared, on my keyboard.). Greek or Electrician speak, maybe.

1 Like

Ok thanks for that .

1 Like

Here is a chart that I made for my Diablo. As you can see the longer the light cycle the greater the DLI is at the same light output level as read in Lux or PPFD.

And here is the recommended DLI at different plant stages.

Yes you can use the 350R for veg and flowering both.
You may start researching your electrical on your own, find out how many circuits that are feeding the wall receptacles. If there is more than one it will be good. Typically there is about 7 devices, (individual lights or receptacles), on a circuit to meet code. Some electricians wire the lights and receptacles on the same circuit to save wire, and some wire the lights and receptacles on a separate circuit so that if a breaker trips it will not kill everything in the same room.
If you are lucky there will be three circuits; two on the receptacles, and one on the lights. If you only have one circuit feeding that room, you are going to have trouble suppling power to anything more than the 5x5.
You can always just put two 350Rs in that 5x5, and get started with that very quickly, since you won’t need an electrician for this.
I hope you don’t think that I am just trying to rain on your parade, and discourage your plans. I am just trying to share what I have learned from my experience. I really believe that if you are growing for personal use, you will be very pleased with a 5x5 tent that is dialed in, running 4-6 plants.
Feel free to ask any more questions! My friend.


I told my electrician I needed enough power and outlets for things like table saws, lights, a separate 15 amp service for a portable AC. He ran 3 separate 15 amp lines to my work shop and studio. 1 for the ac, another for lower wall outlets and another for wall outlets that are work table height. I had the extra space in a nearby electrical box and I was set up in no time. The space was rough framed only so it was easy to pull the wire etc. My son helped wire the outlets when I was ready.

1 Like