The point is if the metal railing of the balcony is grouted to the concrete balcony, it is effectively grounded and so if there is any possibility of touching both the energized conductive part of the receptacle in the balcony and the railing simultaneously, there is risk of electrocution.
Because if the said railing is bonded to the exposed conductive part of the receptacle, the risk of shock/electrocution will not arise even when the upstream OCPD does not operate within the 'safe' time on fault to the exposed metal part of the receptacle.
I want to know which code rule states what are to be connected to the EGC in a residence. Thanks.
If concrete balcony is not on grade, is not supported via concrete or metal structure that is grounded, then the balcony is not grounded. If the railing happens to become energized you can do exotic dancing on it if you wish, and have no risk of electric shock, you are no different than a bird on a bare overhead conductor. Bring something of different potential in close proximity and you increase the risk of shock or electrocution, but same risk goes for any metal object that has similar circumstances whether it be indoors or outdoors. We have many metal objects around that we do not typically bond to the electrical grounding system. Some of them include metal doors, window casings, metal roofing, siding, metal hand railings (sound familiar), complete metal piping systems are usually grounded, but isolated metallic sections of a system often are not, drainage gutters and downspouts, there are countless small metallic objects too numerous to mention that are not bonded to the electrical grounding system, from simple nails or screws into non conductive materials to drain grates, or cabinet hinges or other similar hardware or even portable furnishings with metallic parts.
