Two Prong Outlets

[John F. Bell]

Think about this. Most electrical appliances today do not have a three prong cord. Only metal case appliances, or computers which need an equiptment ground to shunt surges to. A wiggy is still in my tool box, cheap, effective. Back in the old days we had a hot and a ground, no neutral. Now, the neutral and the ground wire generally go to the same bus bar in the breaker box. Is the neutral grounded? Of course it is. But.. it is not called THE Ground. If whatever you have plugged in to the outlet does not have a three prong, grounding cord, you do not need a ground.

[Yuri Olhovsky]

Originally Posted by jfarsetta

... what does "outdated by today's requirements" mean?

Joe, what I mean is that neither NEC nor CEC allow installation of two prong receptacles in today's construction. My reply to the initial post was based on the assumption that two prong receptacles were wired with old cloth covered two conductor romex. In this case you either need a dedicated ground for computer equipment or GFCI. If there is a system ground and the outlet box is grounded by some means, then there is no need for replacement of two prong receptacles unless one needs three prongs. And yes, you are right here
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[whandley]

Originally Posted by jfarsetta

Correct me if I am incorrect, but Yuri's statement regarding a 2 prong being ungrounded is innacurate.

If the system is grounded, and the ground is extended to the box, and the receptacle is mechanically bonded to the box, then the receptacle is "grounded", no?

My thoughts are that the difference between a 2 and 3 prong is that they are both technically grounded, but the 3-prong allows the system ground to extend to the applicance it connects to, if a ground plug is required.

Cheater plugs should have the green wirre, or green metallic thingie, securely fastened via center screw on the receptacle cover, otherwise using them is a no no.

So, assuming the system is indeed "grounded", am I right or wrong here?

Most the two hole ungrounded outlet systems I run into are supplied by two wire cable, no armor, how can the box possibly be grounded?

[Joe Farsetta]

Will,

The system you are describing is one of ungrounded receptacles. The original question went to how to test a two-prong. Yuri chimed in that a 2-prong isnt grounded. Playing Devil's Advocate, I pointed out that the presence of a 2-prong receptacle doesnt necessarily mean that the receptacle is ungrounded. That determination is based on examination of the system, itself. Like cloth covered cables with no ground, versus BX or Romex, with ground path included.

[Greg Fretwell]

Although a lot of places ignored it, the GI Bill/FHA required a grounded wiring method in the 50s. That was either AC cable or the reduced size Romex. That still got installed with 1-15 receptacles and the only thing grounded was the box. It did allow the adapter to work though as long as the device was made up tight to the box.
I know they actually had GI/FHA inspections in the DC area. That probably didn't happen out in the hinterlands. In 1971 the house I bought would not pass the GI inspection. (Aluminum wire)

[mthomas2]

I'm looking at this thread because I've decided it's time to revisit my protocol for the kind of situation I encountered last week: a large older three-story residence with many receptacles which did not accept grounded plugs, connected to branch circuits - some of them originating at load side panels - consisting of a combination of still active knob and tube, older nonmetallic cable, armored cable, and wiring running through conduit, with all of these methods connected together in various combinations throughout the structure. (A branch circuit might exit the service panel in conduit, continue on through nonmetallic cable to a connection with armored cable, be joined to knob and tube in the attic, and then dive down back into the house connected to who-knows-what).

Given realistic time constraints, for what and with what would people here have inspected - and not inspected - these outlets, how would you have reported the inherent limitations of the inspection, and what advice would you given your clients?

[Tab M. Wilcox]

BX is not allowed to serve as the grounding condutor. Correct?

[Greg Fretwell]

If you mean Type AC when you say BX, the answer is the armor can be used for the grounding conductor. This has required to have the bonding strip since 1959 but it was officially called type AC during the Hoover administration (1932NEC).