Need Electrical Advice Please

I am in process of planning my grow room and I have an electrical question. This may require someone with some electrical background. I'm a little clueless so any help is greatly appreciated.

I am planning my grow in a building that is about 300 yards from my house. It is wired for electrical and there is 110v and 220v available. There are both 110v and 220v plugs around the building. The overall size of the grow will be 13' x 13' roughly.

The building has power from a fuse box in the building. However, everything runs to a 50 amp double breaker in the breaker box in the house. I did some testing earlier to determine this. Switching the breaker kills everything to the building.

I'm trying to get an idea of what's going on in the fuse box. I don't necessarily trust it, but I think it might be alright and I'd like to avoid calling in an electrician. It might suck, but if a fuse blows I guess it would be no different than a breaker tripping. I have attached an image as reference for what I'm trying to determine.

There are two large boxes at the top of the fuse box. One has a label that says double poled. Keep in mind I bought this house and I'm not sure if the previous owner labeled these or the owner before that. What are these boxes?

Next there are the fuses. From left to right.

The first is a 30 amp fuse with a label that says 20 amp. So I'm guessing it has a fuse that is too large.
The second is a 20 amp fuse with a label that says double poled. I'm thinking this must be for the 220v power.
The third is a 20 amp fuse with no label.
The last is a 30 amp fuse that again is labeled 20 amp.

Based on the 50 amp breaker in the house at 220v I'm guessing this is broken up at the fuse box. Does anyone have any idea from looking at the photo what's going on here. Am I looking at 20amps for 220v power and then 3 different 20amp 110v power sources?

I kind of thought the fuses in the fuse box would need to equal the 50 amps coming in from the house.

I'll keep it simple.

Do you have anything really running in the barn/garage besides regular lights?

If you don't use it for anything else I would pull the box, go get a new subpanel, there $40 and will come with breakers. Hook it up. You probably have an old school #6 wire coming in.

Next I need to know what you plan to run. I would go with 4000 watts, 18000 btu ac. Lights will draw 18 amps on 30 amp breaker, ac will pull 13 amps on a deticated 20 amp breaker, then add a 10 amp breaker for misc fans/pumps. Also get a ac with a heat pump for winter months.

Last, a continuous draw over 100 feet requires special attention. Over 250 feet is a problem. And remember that you inly use 80% of that 50 amps which is 40. If I were you, I'd measure the distance to the location and check the wirest size.

What do you wanna run?

Thanks for your help. I'll try to answer your questions as best I can at this point.

I'm not sure about the wire coming into the building. It actually looks like there are 3 black wires coming into the fuse box from the main breaker and not just a single wire. There is an old AC window unit that is coming out that runs off 220v and then there are a couple of fluorescent shop lights that plug into 110v outlets in the ceiling. There are 110v and 220v outlets around the building. The building is at least 300 ft from the main breaker box at the house.

As far as overall size I plan on framing in a contained, sealed area within the building. This will be for both flower and veg areas. The flower area will probably be around 7' x 13' and the veg 4' x 13'. I could configure it a little differently, but that's the plan for now.

The ideal power requirements will include:
Lights

• 3 x 1000w HPS or 4 x 600w HPS
• 1 x 400w MH
• a few CFL's for the cloning area

Air Conditioner

• I will replace the current window unit with a new A/C unit. Not sure if I should use a 110v or 220v. I was hoping to save the 220v circuit for lights unless both lights and A/C can run off the same 220v circuit.
• Dehumidifier - I'm not sure if it will be needed at this point. I'm in the southern U.S. so the humidity can get pretty high at times. The A/C may help with this but I'm not 100% certain.

Pumps & Controllers

• Light controller - I was hoping to use some type of light controller for the flower room.
• Pumps - I will need about 5 EcoPlus 396 pumps
• Pump Controllers - I will have a 1 min / 5 min timer on the pumps.
• CO2 - I will have a CO2 regulator hooked up to CO2 tank and ideally if possible will have a CO2 controller in the flower room to help control PPM levels
• Reservoir controllers - I will have at least 3 possibly 4 PPM / PH / Temp controllers for the reservoirs. I don't think they have a significant draw, but it's probably worth noting.

I'm fairly handy, but don't have a lot of experience with electricity. Is a sub panel difficult to install?

I didn't get any alerts, wierd... anyways,

I would gut all wiring in the building. Or just disconnect it. Start fresh. Get that subpanel. 50amp. It's easy to do. Just those three wires coming in. Your ac will keep humidity down when lights are on. When they go off you'll need one. I think a smaller 65 pint from Walmart would work. I use ebay and craigslist alot.

Now your light selection will dictate everything so that's first. 1000w hps is way to go. I prefer t5 over mh cause they get so hot. Also I would get a tent instead of splitting room but that's me. If you do go with mh for veg go with a 8 light controller that has double trigger cords, it will let you do both veg/flo with one controller.

I'm sure I missed something, but first figure out your flower lights. I like being able to adjust them on hot summer days.

Id Use pladtic sheating. Thicker is better, 4mm or more. Panda is way to go but pricy. Seal up whole room. Keep cool air in and light in also.

In winter months you may not even need ac. Again, get one with heat pump.

This your first grow?

If doing hydro i also suggest hydrogaurd. Is one of best products out there. Also I use gh maxI serirs. Simple two part powder. Cheap N ph balanced. And koolbloom to finish.

What type of ac were you going with?