Growroom Electricity and Wiring

[rives]

One of the first things to keep in mind is the 80% rule. It says that for continuous loads, defined as any load over 3 hours in duration, you can only use 80% of the circuit rating. So right off the bat, you need that much more power than your load calculates to.

It appears that your main panel is only fed with 100a. The first thing that you need to do is figure out if the main panel is going to be adequate to carry the existing household load plus the new load from the grow room, or if you are going to need to change out the main panel first.

For what you are looking at, the best way to approach it would be to run a subpanel to the growroom or in it's immediate vicinity. Considering the above rule, the minimum circuit that you would need is 30 amps - 24 amps would be available on a continuous basis, or 5760 watts. This is a lot closer to your projected load than I would want to install, so you are probably best off with a 40-60a feed. With this and a pretty good-sized subpanel, you should be able to run as many dedicated circuits as you want, along with a combination of special breakers like GFCIs or AFCIs where appropriate. This will keep all of the growroom wiring localized instead of having to run clear back to the main with everything, and it limits the space that is needed in the main panel.

In order to do this, you would need to set a double-pole breaker in the main panel of whatever ampacity you decide on. It looks like there is room at the bottom of the panel if the busswork extends down that far. This breaker would then feed a cable that will power the sub. If the distances aren't overly far, then #6 wire (these are all assuming copper wire) is needed for 60a, #8 for 40a, or #10 for 30a. I like having a main breaker in the subpanel just for convenience, but it isn't required.

 

[OldSchoolGreen]

Thanks so much for the info, rives.

 

[surfguitar]

Hey rives quick question, I'm getting a full
On panel/controller from dxsoundco that hooks to a 50 amp receptacle, I'm gonna have my electrician wire it all up for me but here's my problem. I have a really old 100amp box and his concern is there is no room for the breakers, which is correct but I should just be able to remove unneeded breakers and replace them? Or will it be a lot smarter to just upgrade the whole box to a new 200amp service? That option is a lot more expensive but probably safer in the long run and something I figure I will have to do eventually?

Thanks for any input!

 

[rives]

Without knowing exactly what your panel is hooked up to, it would be impossible to say how many "unneeded breakers" are in it. Without a lot more information, I would lean toward changing the service out. If you are planning on running anywhere near the capacity of the DX panel, then you have very little power left for your existing loads. The 80% rule mentioned above applies to the main breaker, too, and 100a services have been pretty well obsolete for a long, long time because they are inadequate for most homes even without a grow going on.

 

[VolcanicDirt88]

so if they are obsolete then what is the norm now

 

[rives]

In most places, a 200 amp service is the standard.

 

[packerfan79]

Quick question. I'm in a 2 bdrm house with a 100 amp service.I have a 12x12 in my garage and 6x6 tent for veg.I added a couple lights this round. But have been nervous to get every thing going
Using 37 amps is that to much on top of normal house hold stuff?

 

[rives]

I couldn't tell you without knowing how your house is set up and your lifestyle. Electric ranges and dryers have 40-50 amp circuits, water heaters are usually 30, air conditioners can be all over the map. Offhand, I would think that you are pushing things pretty hard.

 

[packerfan79]

Rives I got swamp cooler no AC 2 fridges 1 flat screen gas stove small dishwasher computer

 

[packerfan79]

Oh and a gas dryer

 

[rives]

It sounds like you might be doing alright with the 100a service, depending on the age of the refrigerators. I bought a Kill-a-watt a few years ago and found that my '60's era freezer was costing me about $45 a month! It quickly became my veg cab.

Most swamp cooler fan motors that I've seen are pretty good sized. It's really hard to tell where your consumption would be - my house used to run about 2000kwh/month when the kids were home, with no grow going. Now it runs around 6-700kwh/month with a veg cab and usually a tent flowering.

 

[packerfan79]

older fridges I was thinking Mabey unplug 1 fridge. The wife won't like it though. Probably just add 1 more light. I can run em all In the winter but not spring and summer

 

[surfguitar]

Thanks rives! I really want to upgrade but the 2k price tag is kinda prohibitive at this point. I know I have one breaker free for sure that's being used for a 15amp 120v dedicated line. Based on my power consumption which is pretty nill I figure I should be able to replace one of the breakers that goes to the living room and just not have power in that room. The grow would be 5400k in 240v lights and around 1500k in fans/climate control at 120v, so about 40amps which puts me at exactly 80% of 50 amps.

 

[Space Toker]

sorry wrong thread! I should spend more time here instead!

 

[leedsutd95]

volt drop only relative on long circuits

 

[leedsutd95]

In most places, a 200 amp service is the standard.

in UK its actually 100 amp for most domestic

 

[High Country]

I hate electricity…scares the crap out of me so leave it to an electrician…over here in Oz it's 240 V.

 

[rives]

in UK its actually 100 amp for most domestic

Just for the record, my comments/advice are pretty well restricted to the US. While electrical theory isn't specific to any locale, codes and practices are. In the US, the only place that I've seen widespread use of 100a services on new construction is in Hawaii. They don't see the heat/cooling loads that most of the rest of the country does.

Regarding the ampacity of your domestic services, I think that it is roughly comparable to the US. My understanding is that all of your residential electrical gear runs on 240v, whereas in the US it is largely restricted to 120v with the exception of large appliances. The total wattage available becomes pretty equivalent - 240v x 100a = 24,000 watts and 120v * 200a = 24,000 watts.

 

[OIBI]

I'm looking at installing a dedicated 240v 30 amp breaker. What's the most efficient and cost effective way to step down 240 to 120? I thought about just using the plug-in step-up/stepdown transformer, but I can't find any efficiency ratings. Something I could wire inline with a string of outlets would be a lot more convenient, but google only seems to bring up the plug in type.

 

[rives]

240v is actually two phases of 120v, so if you carry a neutral (the white wire) along with your circuit, you can make (2) 120v circuits out of a single 240v circuit. That is going to be the most efficient method, and perhaps the most cost effective if you haven't run the circuit yet or there is a neutral available. Amazon carries some transformers that are pretty cheap, but any transformer is going to have some losses associated with it. If you need to use a transformer, the price is going to go up pretty quickly with increased capacity, so sizing it reasonably closely to your needs would be a good idea. However, they need plenty of extra capacity to get the loads started.

Using a neutral with your circuit is by far the best method.