[MPL]

I am setting up my next project in my garage. I want to add a 240v line for the lights and run everything else off my 15a 120v lines.

I'm comfortable with working with electricity, but I am not sure how to add a separate 240v circuit. My breaker panel is in my garage. I have one slot left on it if memory serves. I also am a safety nut, so can I add an arc interrupter to a 240v line at the breaker? I'll have GFCIs on the 120v (replacing the standard outlets myself - easy peasy) and would like a GFCI on the 240v for additional protection.

I have had a housefire before and am not interested in repeating the experience. Fortunately it wasn't grow related and the cops and fire department didn't have any issues since my entire set up met all building codes.

Also, my room is a separate 8'x8'x8' "shed". I'm building it with standard 2x4s and OSB. If I have the money I am going to put drywall inside and insulate the walls and floors. Anyway, would I be better off running the new 240v through the walls and to an outlet, then from the outlet to a short extension cord, into the cabinet and to the light? Or, would I be better off running the line directly to the shed and installing the outlet inside the shed (done to code, with proper electrical box etc.)? I think running the extension cord would be easiest. Is there a receptacle I can install that allows me to plug the extension cord into something then run the lamp cord from inside the shed? I'd prefer not to run the cord directly through the wall.

Thanks!

[RomulusUSA]

Google AFCI breakers for your panel brand and see what you can get. I couldn't get a 75amp so I skipped it. A house fire sounds like a wake up call for sloppy wiring, so make sure you do it right and don't worry about it.

What is your total amp load? This stuff isn't too hard to figure out if we have some numbers.

If your main panel is full, what we want to do is add a sub, and convert at least one of the existing breakers to be a tandem breaker. Google those, they're pretty cool. You may want to consider doing some load balance calculations here, depending on what type of load you run. Balance is reasonably important.

If you want to do it to code, you'd want to use the proper size of conduit and run the conduit from the box to the 'shed', and then put the sub in the shed. I'd do that so you can run it all via the sub vs with 2 different lines coming into the box.

So lets start with:
*How much distance
*How many amps TOTAL (240+120), if you list the devices, amps, and volts, that may be best for us.

I priced out a 100amp sub/misc for install 25ft from the main, and it would be around $300-350 from local stores (The orange one plus the one I mention below). I called around to a couple local stores, one of the chain sparky pro shops here has large gauge copper for a solid amount less than HD. I like CU because it isn't prone to corrosion and it requires a smaller wire for the same amp cap.

[Phillthy]

skip the extension cord. they are for fires. you need two slots in the breaker box for a double pole breaker for the 240 circuit. how many lights are you running and what wattage?a 1k watt light will draw about 5 amps of current at 240. 4 lights x 1k would be about 20 amps of current. never run more than 80% of the breaker so you would need a 25 or 30 amp double pole breaker.

use UF or (underground feeder) cable. you will need 3 wire plus ground. 4 wires total. you can bury that cable a few inches in the ground. it is best to place it in a conduit. make sure you mark where you put it so you dont accidentally dig it up later.

run the cable to a sub panel in the shed. place your breakers in that box that will power the lights. if running 2 or 4 lights, i like to place half on one circuit and half on the other. same math applies. run the cable from the breakers to your outlets. lastly with the breaker out of the box in the garage, wire up the two power leads, ground etc... place the breaker in the box and throw the poles. use a 240cv outlet tester to make sure you have wired up everything correctly and then plug and play.

[Phillthy]

you shouldnt need more than a 50amp sub panel in the shed. i run an 8 x 15 x 8 room with 4k, co2, ac, fans, cloner, etc with a 50 amp panel.

[RomulusUSA]

^^ Rockin'!

If you bury the wire, please, at least 18-24". That's my only comment until we hear back from the OP.

MPL, also, for amp/gauges.. You may know this, but a good reference always:
14ga/15amp
12ga/20amp
10ga/30amp

[MPL]

My wiring was perfect. The Fire Chief inspected everything to determine the cause and said all of my wiring was to code and he found no problems there. It turns out an outlet near my grow that was going bad somehow shorted and caught on fire. In my experience building codes are there for a reason and I stick to them.

I want to have a single 240v line, 30amps should be plenty. I'll only be running my HIDs off it. 2x1kw = ~8.2amps. That also allows room for expansion up to a total of ~4kw, like Phillthy said.

I want to have two 120v lines, for things such as pumps etc. 15amps each should also be plenty, but 20amps would be nice for breathing room.

So for total amp load I shouldn't be pulling more than 15-18 amps from the 240 line and no more than 15amps each from the 120. In fact I doubt I'll need more than a single 120 but I'd rather have it and not need it than need it and not have it, ya know?

I can do conduit no problem, but I'll probably have to run it along the baseboard inside the garage. I could do that and run it to an outlet (subpanel?) in the grow room, instead of putting the outlet in the garage wall. I'm not sure if that's proper though, I'll have to check it out. Hmm, I guess if I explain the layout this will make more sense.

I have a garage that is well insulated (except for the garage door), carpeted and in good shade for 90% of the day. It's about 35'x15'x15'. I am building an insulated room in the back of the garage where it is coolest, measuring ~8'x8'x8'.

The circuit breaker is towards the front of the garage, on the same wall as the grow will be situated. The lines won't have to be more than 35' long. We'll call it 50' to be safe.

I may consider hiring an electrician as I've never run new circuits before. All I'd need him to do is hook the new circuits up, I can run all the wiring and add the outlets myself. Do I need to worry about the breaker box pulling too much from the power lines? Since I only have one slot left in my current breaker I'm gonna have to add another one I suspect. Breaker = panel yes? When it comes to household wiring I only know the very basics. I can wire a ballast, add outlets, add ceiling fans etc. but haven't done anything past that. Contracting the work is starting to sound pretty good...

Thanks for all the input!

[RomulusUSA]

Wow sketchy! Maybe I should consider using AFCI's..

I'd put the subpanel directly in the room. Based on what you are saying, do you want a total of 50amp@240v in the subpanel? Just run a single 50amp line to the subpanel, and put breakers in there. Simple. Running 2x12ga+1x10ga seems really dumb to me. Get the length of 6/3 that you need and call it a day. I don't think conduit is required for a garage install, but its always a good idea. I am not an electrician so I have no idea on the NEC for that.

https://www.platt.com/platt-electric-...spx?zpid=69540

As I said in my first post.. Your panel is full, you ought to swap a few breakers with tandem breakers and toss in a 50amp/240v and rock out man.

Also, I support hiring an electrician if you don't feel comfortable. Fully! But really, this is pretty simple stuff. Learn to use Google, there are -so- many threads on -so- many forums as to how to add a subpanel. Really, its not hard. I have done a couple installs, and am a newbie (tho I am very very mechanically inclined and good at following directions..) and feel quite comfortable with it. If I get confused, I resort to pros online

[rives]

In answer to your question, circuit breakers go into the panel. If you only have one slot left, you could either do as Romulus suggested and go with some tandem breakers (or half-size breakers depending on what is available for the brand panel you have) or you could swing a couple of nearby circuits over to the new panel.

The wiring will need to be protected from mechanical damage by either getting it into the wall or using conduit. Oversize everything by a comfortable margin (I invariably seem to outgrow the panel....), stay at a maximum of 80% of the rated ampacity of the circuit, and use quality components. For your receptacles, I would use commercial or specification grade with screw connections for the wiring rather than the stab-it-in-the-hole junkers to avoid a replay of your earlier problem.

You need to insure that you have adequate power in your existing panel to drive the new one. Is the existing panel the main or is it a sub-panel?

[RomulusUSA]

Ah good call - The garage circuits, depending on how they are ran, could be done off of the sub.

Rives - Can't you run Romex out of conduit? I thought you could. If not, my shops wiring is sketchy as hell, as has every inspected un-sheetrocked garaged I've been in... If romex needs conduit, what's the most cost effective method? PVC?

[rives]

Romex is supposed to be protected from mechanical damage - that protection can be a some type of raceway, wall cavity, etc. Although it can go in conduit, it would be difficult to accomplish - it is too stiff, the outer covering is too "gummy" to pull well, and it would be almost impossible to pull in another circuit later. If the wiring can't be hidden in the walls, EMT or flex would be my choice for an environment that isn't too abusive, and rigid for places where things really get banged around.