On 3/27/2013 10:53 AM, bob haller wrote:
On Mar 27, 12:32 pm, wrote:
On 3/27/2013 9:37 AM, wrote:





On Wed, 27 Mar 2013 09:11:04 -0600,
wrote:

Self tapping screws can not be used as the electrical connection to the
box (as gfretwell wrote). A wire would have to be added to the neutral bus.

You can use a thread forming machine screw if the metal is thick
enough.
This is what 250.8 says about it

(5) Machine screw-type fasteners that engage not less than two
threads or are secured with a nut
(6) Thread-forming machine screws that engage not less than two
threads in the enclosure

This excludes a course thread sheet metal screw.

Most parts of a panel are probably not thick enough for 2 threads.

If you have a 100A feeder, are 4 threads (2 screws) adequate for a
ground fault (paint blocks direct contact). It makes me nervous.

Presumably the ground bar that is added is "listed". Not all of them
are. Some are UL "recognized" components that are not the same as
listed. (Or the bar can be accepted by the inspector.)

The HEAVY COPPER line between the original bar and the added one takes
care of electrical conductivity

You added a ground bar?????

The panel was obviously obsolete. The house should have been demolished.


The home inspector flagged the panel because the original inspection
stickers signature had faded The sticker was fine the signature cold
be seen but not read......

Any house that old is obsolete. Who knows what else has faded. The house
should have been demolished.