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Up or Down, The proper AC outlet mounting in a home

The IEEE standard 602-1996, section 4.2.2 advises that hospital-grade outlets be used and that they should be mounted with the ground pin or neutral blade up to assure that any metal that may drop between the plug and the wall will most likely contact an unenergized blade.

I have done work in Many,many homes, and I have seen the outets in both positions. With the chassis hole on top, and the chassis hole on bottom. I have even had many disputes about the proper way to install them. BUT, if you look at the writing on the outlet, you will see that they wouldn't print it upside down!. So the logical way of installing an outlet, is with the chassis hole on the bottom. What do you think!

First, most outlets are installed with the chassis pole on the bottom. In this config. the chassis is the last of the three protusions to be removed when the plug is removed, therefore providing a certain amount of protection.

The other thought is if the chassis is at the top position, and should the plug become loose and ajar, as would be the case of an old outlet that has seen much use, and sometime the plug sort of hangs there and the blades are partially exposed to a mishap, the top exposure would be the chassis and not the hot and neutral conductor and thus be less apt to cause injury.

On the other hand, it is the circuit interrupting device at the main should disconnect the power  should something come in contact with the hot and neutral conductors, if mounted at the top, with the chassis at the bottom.

Some engineers say the chassis is on the bottom for a reason, and the manufacturers seem to be in agreement.

The NEC does not specifically state which way the chassis prong should be, except in the round about way, ..."shall be installed per manufacturers instructions..."

The final statement: With the chassis prong on the bottom, it is almost impossible to break the outlet when removing a 3 prong plug. I have replaced 100's of outlets, that had the chassis on top, that where broken by the aggressive removal of the plug. The people lift on the plug while removing it, if you do this action with the prong on the bottom it is harder to break the outlet. SO as far as preventing breaking the outlet, mounting of the outlet with the chassis on the bottom is the best. As far as plugging in or out of the power cable it is more ergonomically correct to have the have the ground pin on the bottom as you thumb can rest on the flat part of the cord head (the plug itself) and provide a more secure grip for insertion and removal.