Switch – 2 wire lamp cord – which one is live

I have a similar Ikea fixture, but it came with a metal sleeve that tightens with a screw--this part sits below the cap, but this light has a rod (rigid, not the cord itself) for this sleeve to work on.

Did you buy it new? If for some reason you didn't have the instructions and therefore couldn't verify if a piece was missing, you can find those here: http://www.ikea.com/ms/en_US/customer_service/assembly_instructions.html I know you can order replacement parts from Ikea, at least if what you need hasn't been discontinued.

Assuming you have the instructions and all the pieces, I think your best bet would be finding a rubber O-ring (or several) which match the cord diameter, and sliding those up to keep the cap up....or using a twist-tie painted to match the cord. Once you have the cap up reasonably flush with the ceiling, you could use clear silicone caulk around the rim of the cup, which can easily be peeled away later if you're renting.

Finally, is the hook all the way in? Perhaps screwing it up further into the ceiling would make the cap go higher.

Best of luck!

You should be able to purchase a three wire cord with a molded three prong grounding plug on one end open wire ends on the opposite end. These are often sold as electrical appliance replacement cords and should be available at most good hardware stores and big box type outlets.

Here is an example of one type of these cords:

Make sure to use proper strain relief on the core end at the lamp to keep stress off the internal electrical connections.

These cords are very similar to if you got a three prong extension cord and cut off one end. You could do this except in many cases any safety agency listing for that extension core becomes non valid once the cord is modified. This may also be a reason to check if the appliance replacement cord that you purchase is marked with a safety agency listing/logo.