Self Grounding Receptacle Metal Box
Ground wires are spliced together and attached with a pigtail to the box and receptacle.
Self grounding receptacle metal box. If the box is recessed and properly grounded then self grounding receptacles are enough unless the jurisdiction in which you live has more to say on the subject. Metal receptacle outlet boxes must be grounded and one method is to pigtail the ground wire so that it is attached to the outlet and the metal outlet box using a green grounding screw. In this arrangement both the receptacle and metal box are grounded. A gfci outlet installation does not protect equipment from power surges.
Sonja yes you are correct. In a system with metal boxes the pigtail method is considered the most secure. This doesn t turn an ungrounded outlet into a grounded outlet but it does provide protection against shock. But the yolk of the receptacle has to be bonded to the box so there can t be space between the yolk and the box.
Where the box is mounted on the surface direct metal to metal contact between the device yoke and the box or a contact yoke or device that complies with 250 146 b shall be permitted to ground the receptacle to the box. The easiest way to upgrade an ungrounded 120v receptacle to get ground protection is to replace it with a gfci outlet. Under current recent nec rules i believe the grounding pigtail is required so that the outlet will still be grounded even if it s not screwed to the box or because the ground pigtail is regarded as a better connection to the box than the mounting screws are i m less sure of the intent than that current rules require the pigtail. Self grounding electrical outlets are designed to protect you from electrical shock.
Consider that if they considered the mounting screws. Electricity is always in search of the simplest path to reach earth. How to ground receptacle outlets. Protect yourself working in electrical outlets with this tool i use fluke flk2ac pocket sized voltage detector voltalert on amazon.