You can locate your electrical box wherever you please. I'd follow local electrical code over IKEA instructions.

Bought this less than a year ago. Had an electrician install it. Not easy to assemble or install. The left light is now flashing if the door is closed and the right light is not lighting at all. The wire leading from the right light has a noticeable break in it, probably due to the normal opening of the door. When I contacted IKEA about it they were no help at all, stating that they don't have the wires and I should contact and electrician . I like the look but will now have to get an electrician to take the cabinet off the wall (it's heavy) and do the wiring. Faulty design. Made to break.

I have experienced the exact same issue with the IKEA Storjorm cabinet as Colleen above experienced. Lasted less than a year and as Colleen mentioned it suffers from faulty design.

There is an issue with their wires the stress of hr flex causes them to break - I just repaired mine with a short length of wire which I then wrapped with electrical tape. It’s a really easy fix and is nothing more thtan a broken wire but shame on IKEA for not offering replacement parts. I attached a photo to show the area of the break and the repair before wrapping it for insulation.

If you doninstall make make sure you leave enough slack to allow the open and close of the door. IMHO if the wire ran behind he light rather than in front it could have been made to handle the stress.

Complete break took a small wire and connected both ends - note if you needed I think you could take off the light and wire and resolder inside but this way it will have plenty of slack now

looking at your pic that is exactly what instruction recommend not to do. you should leave a loop of wire as it showed in the instruction's pic. see page 13 on the instruction: http://www.ikea.com/us/en/assembly_instructions/storjorm-mirror-cabinet-w-doors-light__AA-1272240-2_pub.pdf

I left a large loop in the wire to the door and have not had any problems so far. Been installed almost a year.

The electrical box cover is supplied by you from a hardware store. The cover stays exposed behind the cabinet to facilitate removal of the cabinet at a later date. Electrical junction boxes are not allowed to be hidden inside walls per National Electrical Code.

I love mine and plan on purchasing two more for my other bathroom.

do I need a separate light switch for this cabinet? Are the lights meant to just be on all the time?

Timely question as my electrician is installing it now and neither of us can figure this out. I think the answer is it needs it’s own light switch

I installed this about 3 years ago.

The electrical box is mounted I side the cabinet at the top and the wires run behind it, back through the cabinet and into the doors.

I've wired them in series with the ceiling lights so that the mirror lights turn on with them using the same light switch.

One of the wires have sheared due to stress. I've repaired this by splicing in a replacement section and using heat shrink. The wires leading to the lights are pretty low voltage so there's not a huge fire danger, but it is a pretty bad design.