'Recessed' back box?

[JohnW2]

Electrically I don't have an issue with them, of course the fire resistance raises doubt with some ....

I'm certainly no authority on such things but it actually seems remarkably difficult to 'ignite' wood, which seems to require at least 'a lot of flames', not merely contact with something very hot. It seems that putting a piece of red hot metal in contact with wood will merely 'scorch' it, and one can even direct a blowlamp at a piece of wood for a long time before 'ignition', rather than 'scorching'.

I therefore suspect that a wooden back box would only ignite if there were already a well-established 'flaming fire' . Am I wrong ?

 

[morqthana]

At least one property (and I believe a second) had no back boxes at all, just cut out a hole, drilled and plugged for long thin woodscrews, I assume one of the plastic drilling template thingies had been used.

In my home the original backboxes were wooden and many of then are still in use, in those days each accessory came with two 4BA screws and 2 wood screws.View attachment 395362

My parents' house had some wooden boxes left for light switches, but the switch plates had little toothed lugs which pivoted outward as you tightened the mounting screws and dug into the sides of the box.

 

[ebee]

(2) and (3) make sense - but as for 'airflow'. there usually won't be any in the case of a metal back box, will there? ... in which case I wonder what 'considering' you do about it?

OK - Airflow - not airflow in the usual sense but air flowing in a confined space such as a 25mm box rather than a 35mm box for a start can severely life limit the dimmer by slowing down convention considerably (pro rata ) , of course the back box will be about 10mm further away too so that could affect things as well I guess.
I have noticed quite a few dimmer failures and I have attributed most to that possible problem