I don't remember if I gave a required tool list with the DIY post [the one in my signature about converting HID light to remote ballasts] or not so I'll run it down here;
1 pair GOOD diagonal wire cutters -- at least 8" to 10"
1 pair of wire strippers -- these are a lot easier to use than a knife but you can get by with a good knife if you know how to use it
A couple of Phillips and blade screwdrivers --OR EVEN BETTER ONE OR TWO OF THE 4-WAY TYPE SCREWDRIVERS
If you will be using crimp connectors, which I strongly recommend, a good pair of crimping pliers
A good razor/utility knife with pointed blades -- I prefer the retractable pocket knife type
These can all be bought at Home Depot, Lowes or harbor Freight -- don't worry about getting the best, but don't get the cheapest because to a certain extent you get what you pay for. If you need me to, I can get a suggested middle priced list with parts numbers for each source, but it will take a while.
Okay, the next step is to obtain a wire extension cord of at least 14 gauge and one of the 400 watt bulbs. Forget about the grow shops or garden centers. Instead of paying way over $50/bulb (and I have been hearing that a lot of shops want close to $100 or more depending upon which high dollar grow brand you buy) search the yellow pages in the telephone book for "electrical supplies, wholesale" or similar listings. Start calling them until you find one who will sell to individuals, or even better if you know any contractors or electricians have them buy a simple 400 watt MH bulb -- if you have a choice of brands at close to the same price, Phillips has an excellent reputation along with Sylvania. I pay $24 and change plus tax for Sylvania and I think $26 and change for the Phillips brand from a different wholesaler locally. DO NOT WASTE YOUR TIME ON BUYING USED BULBS BECAUSE YOU HAVE NO IDEA WHAT THE EXPECTED LIFE OF IT HAS BEEN USED UP. Also the output decreases over time and the older the bulb, the faster it decrease. Some of the newer ones have been made to where they stay pretty consistent until right at the end and then fail very quickly.
Then get a 14 gauge 3 wire extension cord long enough to make both your power cord and your ballast to light cord out of it. You don't need the "contractor grade" and since it will be used indoors out of the weather it can be almost the cheapest one you find. Just be sure that it is 3 wire and at least 14 gauge wire -- 12 works well too but the larger wire makes it slightly harder to work with and needlessly more expensive, unless you already have it. If you are trying to use used cords, make sure that the insulation is good full length and if the ends are damaged, then replace them like my DIY thread suggests. If I was buying cords, I would probably buy them at Harbor Freight or Lowes/Home Depot when I bought my ends. Incidentally Lowes has some very inexpensive cord ends that would probably be just fine IF you always unplug the power cord before messing with the ballast or light cord. I usually use between 10' and 15' for the power cord, although 6' is probably about the standard length with the factory ballasts. Then I use between 15' and 20' for the ballast to light cord. Figure out how big your area is and give your self at least 6' more than the longest distance from the plugins for your ballast to light cord. For instance my room is approximately 15' diagonally so I use 20' to 25' -- the diagonal length plus 6' for height adjustment and a full 8' to maybe even 10' for height adjustment so if you want to you can put the ballast near the floor, run up to the ceiling, across the room, and back to near the floor. For my 12' x 6' x 7'8" high room, most of mine have 35' of cord for each light, 10' for power cord and 25' for light cord. I just kind of hang the cord between the J hook screws that I use to hang the light on one end over to the other hook where I hang the ballast and go from there. A couple of mine are couple of feet shorter than that if the piece I was using wasn't quite long enough and if it was a little longer I just left them alone. Of course I made mine out of old extension cords I had acquired over the years. I probably had 500' of cord around here from projects over the years that had bad ends on them (if you buy the same quality ready made cords are cheaper than 2 ends and the same amount of extension cord 3 wire cable and you don't have to put them together) so when the ends get screwed up I just pack the cord away and go get a new one. Fortunately my being a pack rat pays off sometimes, although my other half gets frustrated with it.
Once you have both the bulb and the extension cord, cut the male end with the prongs -- (I'm just trying to be clear, NOT imply that people, especially women, know nothing because I know better but it is easier to clarify now than after a mistake has been made) to the length that you want your power cord to be.
Carefully remove the wire nut from the black/277v connection and note how far the insulation has been stripped back.
Then trim the outer insulation jacket back about 1" to 1.5" being VERY careful not to cut the insulation on the inner three wires or even worse yourself or assistant if you have one. Somethe steps are a littl easier to do with a spare hand or two. Then strip the individual wires the same distance as the wires currently connected with wire nuts are stripped.
Expose the end of the 120v wire by cutting very short pieces of the cap off until you can pull the insulation off. A better picture of the capped off wire would be helpful here in trying to help you determine where to cut it. If possible put something like a dime in the picture for a frame of reference to help me judge the size of the cap, or just measure the length of the cap.
Then expose the wire for the same length as the 277v one that you disconnect was exposed.
Now cut the exposed part of the 277v wire off flush with the insulation and seal it. For sealing the end of the wire I suggest making a very tight U shaped bend in the wire so the end of it is now lying along the side of the wire. A lap of about 1/4" to 1/2" is fine. Then you can wrap the folded over portion with 2 or 3 layers, or as many more as you feel to be needed, of good electricians tape to prevent the end of the wire from shorting to anything.
Finally connect the stripped 120v white wire from the ballast to the stripped black wire in the power cord using the wire nuts that are already on the ballast, followed by connecting the White COM wire from the ballast to the white wire of the power cord. For now ignore the green wire, it will be sued later to ground the cases of the ballast and reflector/hood directly to ground in case there is a short that electrifies things that aren't supposed to be electrified.
Lay the ballast on its side, screw the bulb into the socket securely but don't over tighten it because you will need to remove later. Now without disturbing the ballast or the bulb, carefully plug the cord into a plugin. At this point it is a good idea to not be touching the ballast or socket assembly when the cord is plugged in.
Watch to see if the light burns. It should only take less that a minute to be nearly steadily bright. Please do NOT look directly at the light because it will at least temporarily blind you when you look away. You will be able to tell if the ballast and socket are working without looking directly at the bulb.
If the light isn't burning steadily within 2 minutes, there is a good chance that it never will, but it will consistently get brighter for the first few minutes.
It should NOT ever take over 5 minutes to settle down to a smooth increase in brightness. Otherwise either the ballast or the socket is probably bad.
After you determine if it works or not, unplug the cord and let the bulb cool down before going any farther. If possible always handle the bulb when cool and with clean hands and a clean cloth or gloves to avoid getting spots or finger prints on the outer shell than can cause hot spots and failure of the bulb.
You might want to take picture of each step like you did earlier so you will have record of how and what you did. I am proud of you and you should be proud too. Most people, regardless of their sex would not be as willing to try some thing like this, especially involving electricity, or do it as well as you are doing without some background.
If the light works, then I need you to get me some close up pictures of the socket end so I can try to walk you through converting the socket to a remote ballasted setup.
TO BE CONTINUED