Question for an Electrician

_RaT_ · Jan 3, 2006

<font color="blue"> but I'm sure he gets tired of responding - only to get attacked for his answers. I'm sure his email-only responses are a protective measure - you can only ignore the riff-raff for so long without getting discouraged</font>

I've not known where this was the case. I do know that how an electrical inspector inspects my work can vary significantly. I've had inspectors teach me and I have taught inspectors. /forums/images/graemlins/wink.gif

HGM · Jan 3, 2006

I'm not a residential electrician by any means. I have always believed that dielectric is a good idea whenever you have it available. Not only does it prevent corrosion, it reduces oxidation and moisture migration inside the wire. It may be overkill, but it shouldnt cause any problems. Just wanted to add the idea that it it might not be needed but wouldnt hurt.

EddieWalker · Jan 3, 2006

Interesting grounding to the box, but not the outlet. It's rare to see anybody using metal boxes anymore, but I see them in remodel jobs I've done.

I'm drawing a blank the last time I saw an interior metal box that was directly grounded. I've always seen the outlets and switches grounded.

What would be the advantage to grounding the box over the outlet? Woudn't it take more effort to do it that way?

Eddie

Highbeam · Jan 3, 2006

On my plastic boxes, I always tie the bare copper wire to the green screw ground of the outlet. No sense in grounding a plastic box.

_RaT_ · Jan 3, 2006

You need to ground any metal parts. In this instance, if you had a portion of the energized wire touching the metal box as a result of the wires insulation being stripped, you in effect have a box if ungrounded that is energized and could be lethal. For commercial, we still only use metal. The conduit is our ground. For residential, I try to use only plastic or non conductive boxes. While it is simple to ground metal boxes, it still takes time. I typically pigtail the ground wire in the metal box before I ever install it. You will notice that metal boxes already have the ground screw hole drilled and tapped. Add about 8" of ground wire to the screw and your set.

I still only use dielectric grease for aluminum. It is the aluninum oxide that presents the problem for elecctrical flow. If your metal and copper are getting heavily oxidized, you don't have a oxidation problem, you have a bad mositure problem that needs to addressed. I have had an electrical inspector make me remove dielectric grease on metal to copper and CU to CU connections. It was on some large hydraulic crimp connections on 750MCM CU. I was not pleased and now only use it when it is called for.

_RaT_ · Jan 3, 2006

<font color="blue"> On my plastic boxes, I always tie the bare copper wire to the green screw ground of the outlet. No sense in grounding a plastic box </font>

Thats good, thats code. If you have more then one copper ground coming into the box, be sure to pigtail the wires. Never wrap more then 1 wire around the ground screw. For residential, I always leave at least one ground wire long and use Buchanan crimps. The long ground wire is what I attach to my outlet or switch.