Originally Posted By: roconnor This post was automatically imported from our archived forum.
Not to throw some fuel in the fire (me … never … lol.), but I spoke to a UL engineer who indicated that not only were residential panels not tested/listed for a flat on the back installation, but they were also not tested/listed for installation for anything other than in the vertical position on a wall or other vertical surface … Hmmmmmmm.
So it seems that anything other than a vertical installation on a wall for a residential panel would not meet current safety standards (not "listed") as a guide (assuming that is put in writing) ... 
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
So it seems that anything other than a vertical installation on a wall for a residential panel would not meet current safety standards (not "listed") as a guide (assuming that is put in writing) ...
If that info is not in the instructions included in the listing or labeling all bets are off.
-- Bob Badger
Electrical Construction & Maintenance
Moderator at ECN