low volt lighting transformer location

[mattmeister]

I am finishing my basement. Currently there is a low voltage lighting transformer plugged in to an outlet and mounted on a floor joist above the new bathroom. I had planned on relocating the transformer and enclosing it behind an access panel with the DWV stack clean out trap. Is it up to code to put an outlet behind this panel to plug in my transformer? I will have to splice the low voltage wire that leads outside the house to extend it down the wall as well. Do I have to enclose that splice in a junction box or can I just wirenut it and forget it (it will be behind a finished wall)?
If this whole thing sounds hokey, what other solution would you suggest? Thanks.

[Wgoodrich]

Junctions must remain accessible and contained within an electrical box.

Transformers must remain accessible. This I interpret would allow your removable door to get to the transformer.

The NEC requires the secondary wiring from the transformer to the lights to be installed as short as possible. This is the only spoken intent on length of wires as long as the wires are capable of carrying the secondary load.

Hope this helps

Wg