Urgent help: fuse breaker box for dedicated line?

I've looked for a fuse breaker box for my dedicated line at Home Depot, but I can not find the one that use 120V. Home Depot has only a few types of fuse breaker box, but none of them use 120V (240V only). Here are my questions
1/ Can I use 240V box for 120V? I asked the guy in store and he told me that I may use it but the current will be double (he's not sure about it).
2/ The one that I've looked for is 240V/60A with 3 slots to put fuse. Does it matter for double the current in case I use 240V box for 120V if I use only 20A fuse?
3/ The maximum slots in breaker box that I found is three. Do they make four slots? Where can I find them?
4/ I see JPSlabs.com have special wire for dedicated line for $3.5/foot. Is it good compare to Romex or THINN wires?
I'm interested in JPS wire because I need only 20' for three outlets from the sub panel.
Thank you very much.
If you don't know the answers to those basic questions about voltage and current, you have no business doing this yourself. You are fooling around with things that can burn down your house if done incorrectly. You should hire an electrician.
In all seriousnesss with the kinds of questions you are asking you need to hire an electrician. I would hate to see you destroy your equipment or worse burn up your living quarters. At least go to an Electrical Supply house near you and ask questions. Stay away from Home Depot or Lowes. They are good places when you know what you want but when you have to ask the kinds of questions you are asking they may not be the best source. Just my two cents.

I ran the wiring for my dedicated lines back to where I wanted my circuit box then hired a licensed electrician to install the box and breakers. This saved me some money on the straight forward stuff and insured proper installation of the electrical connections, also most electricians will use better quality parts than those available at "home centers".
I'm in process of building a listening room, and the contractor will do the dedicated line for me. However, I have to supply all the parts, and I want all the parts will be ready before the contruction starting.
I want to buy all the parts now just because I'm off for the whole week. I'll be busy next week and I don't want to wait for the contractor until next Monday.
I already have dedicated lines in my old room, so I know little about it except for the fuse breaker box, and I don't know where the last electrician bought it.
When asking an electrician for dedicated lines, I advise you to include overload protection as well in the case lightning should strike in the direct vicinity of your home(s). Small extra investment, large amout of security.
I'll second the need for an electrician. Your 240v sub panel will provide 120v. Just use a 1 pole(slot) breaker. 240v would require a two pole breaker. Sounds to me as if your using a fuse box, in that case your hot leg off the fuse and your neutral would comprise the circuit, with the ground for safety purposes. If you double the voltage you cut the current in half, that is why transmission lines aren't the diameter of sewer pipes. If your only running your audio equipment one circuit will suffice. You should pull romex wire 12 guage 3 conductor or 12/3. Thinn is stranded wire with an insulation that is oil resistant. Email me if you have any other questions. Mdoughty@nycap.rr.com
DT. You might try going to a wholesale electrical warehouse where electricians buy their parts from. They might even be able to sell you the box you're looking for and they would be most qualified to answer your questions. Usually in the morning and late afternoon trade people always around.
Are you pulling out of your regular house breaker panel? If so, All you need is a breaker(single pole) of the same brand breakers that are in your box. Using one pole will give you the 120v you desire. Every wire in your house should go back to this breaker panel. If the panel is full(no extra slot) then you have a little bit of a problem. You DO NOT need to install a second disconnect box if you are pulling from your panel. That would be redundant.
You can get single pole breakers of various amperages.
Since you are running a dedicated line, I would run 10/2 Romex.
If you are having a licensed electrician do the actual work, ask him what you need. Also, you may want to get a high grade outlet such as a Wattsgate or Hubbell for your outlet.
By the way---contrary to popular belief, A lot of electricians buy their stuff at Home Depot and Lowes. Both stores offer a "Commercial" sales department and carry a good supply of materials at a reasonable price.
Something sounds wrong here, DT. The "contractor" will do the wiring if you provide the panel? Politely decline - this guy might not be an electrician. Electricians will know exactly what to buy for your requirements and how to legally install. Call in two or three electricians, get a price, labor AND material, and let one do the complete job. Don't concern yourself with voltage ratings, grounding, method of power distribution, etc., - just tell them you want a dedicated circuit from a subpanel. A good electrician will take it from there without even blinking.

Keep a wary eye towards anyone who asks you to buy electrical parts, except, of course, any specialty outlets or wiring. Chances are they won't be licensed or have no standing or credit with supply houses. (Also applies to plumbers, carpenters, etc.)

FYI, honest, well-established contractors will never ask for money up front for materials or "mobilazation" costs. Anyone who does this usually cannot manage their money and will spend your downpayment to finance someone else's job.
I just check the fuse breaker box that has two slots for my dedicated lines in my old room to find out that the last electrician use 240V/60A. So, I think that the fuse beaker box that I've looked for at Home Depot is fine(240V/60A/with 3 slots). I'll shop around to find a fuse breaker box with 4 or more slots because I need al least one or two extra outlets.
The guy who do the job for me is a general contractor. He's expert in building thing but not in electrical stuffs. However, it'll cost me $400-$500 if I call the last electrician, and the price to build the room include everything. I think the job is not hard for him because he just copy the old one. Actualy, I can do the job but I don't want to do it in case something happen he has licensce and I don't.
Thanks for all your helps!
Ps: How's about the JPS AC wire? Is it worth to spend extra money?
WC86: A general contractor is NOT a licensed electrician. They are seperate training, testing, and certification processes. It seems both the general contractor and you are struggling with the proper equipment to specify/supply. Please hire a licensed electrician to do a proper installation. In MN, to get final approval on a building permit would require an approved (seperate) electrical permit.
I have never used/heard the JPS AC wire. I priced it once and it was very expensive. Here is some information from one of my posts on Audiogon (another similar topic).

“I have experimented over the last 6 months with various wires to use for dedicated 20-amp circuits. I have the following wire in use in no special order:
1) 10 gage Romex
2) 10 gage UV
3) Belden 83802
4) Virtual Dynamics 10 gage BX Cryogenically treated with Cryo’d circuit breaker. *

I have not tried the following but I’m sure it works, 10 gage solid THHN (white/black/green) manually (electric drill) spiral twist and snake through conduit.

To my ears on my revealing system I hear NO difference between (1-4)! I think simply using a dedicated circuit with 10 gage copper makes the biggest difference.

I hope all that read this find it helpful, it’s cost me about $500 (out of my own pocket) to complete the testing for my own peace of mind.

* There might be other positive factors to using cryogenically treated wiring besides sonics. It might lower the operating temperature of equipment.
Sorry, I made a mistake. I was confused between Virtual Dynamics and JPS AC wire. The Virtual Dynamics is $3.5/foot, and JPS is $18/foot. I planed to call VD this morning but instead calling JPS. That is why I know JPS AC wire is $18/foot. However, the man that I talked to is very very nice. His system and mine is exactly the same. I'll try JPS cable when my room is done, and who know I may sell my NBS cable to switch to JPS.
Happy listining!
240V are compatible with 120V, I SUGGEST YOU TO GET A CONTRACTOR TO DO IT. Dont burn yourself crispy! Well, as the other mentioned, yu can run the wires first to save! BUT even running wires will have a certain pattern, you cant just run it! Otherwise insurance company will not accept your claim if anything hapened! Also when people come check, you gonna get a summon and you have to take it off. The wires has to go around the frame and wood beans on top and go down along with a metal/wood wall beam. Many many other rules, JUST GET A CONTRACTOR TO DO IT!