I did a repair today on a fairly new house trailer and found a cut wire. What really surprised me was how it was wired. They used self-contained switches that had push-on knife blade type connections (like some of the phone jacks) with no box needed. The romex was run into the switches which were closed up. They customer also complained the lights would dim when the A/C would start, poor connections probably part of the problem.
Hard to believe these devices meet code, I'll have to check on it.

See Section 300.15(E)

Integral Enclosure.

A wiring device with integral enclosure identified for the use, having brackets that securely fasten the device to walls or ceilings of conventional on-site frame construction, for use with nonmetallic-sheathed cable, shall be permitted in lieu of a box or conduit body.

FPN:See 334.30(C); 545.10; 550.15(I), 551.47(E), Exception No. 1; and 552.48(E), Exception No. 1.

There is nothing surprising about lights dimming when the air conditioner starts up. There are a lot of factors that come into play & loose connections are not the usual cause.

Next time you look at a newer mobile home, see if there is a HUD sticker or placeard on it. If there is, the only parts of the NEC that apply are the ones HUD picks. I've even come across a doublewide that had a panelboard in a clothes closet.

Tom

Tom, I don't know if it was a Hud home. The panel was in the closet in this one too.