I found this difficult to assemble, based on the instructions supplied in the box -- it's just diagrams, no verbal descriptions.  In frustration, I went to the manufacturer's web site and found the manual for this unit.  After downloading it and reading through it, I found it MUCH better; they supplement the diagrams with written instructions, so it's easier to understand.  The instructions in the box say, "This unit should be assembled by an electrician or a competent person".  Since I couldn't assemble using the instructions in the box, I guess this makes me an INCOMPETENT person.