Reporting on 2 slot ungrounded receptacles
At least once a week I see older 2 slot ungrounded receptacles. Often, the main service panel and several branch circuits have been properly upgraded, however, some older branch circuits were not updated. You can see in the right picture above that not one branch circuit in that panel contains a ground. Branch circuits may show a ground with a tester if they are bonded to the main service panel with AC or BX cable. (That was addressed in an earlier newsletter). So how do you advise your clients when you see a 2 slot ungrounded receptacle? The best option is to install a new grounded 3 wire branch circuit. Another option is to install a Ground Fault Circuit Interrupter (GFCI). The GFCI should be labeled “No Equipment Ground”. An electrician can also run a dedicated ground wire from the service panel or from a nearby grounded receptacle or branch circuit. A ground could also be installed from another approved ground source (water pipe with proper connections, external panel ground bus, etc). Many 3 slot grounded receptacles are improperly wired because they may be over amped. 15 amp receptacles will have 2 slots, with the neutral being slightly longer and a ground. 20 amp receptacles can be identified as having a perpendicular slot on the center of the neutral slot. Having a 20 amp circuit breaker with 12 AWG on a receptacle rated for 15 amps would be over amped / fused. Although we are not conducting a technically exhaustive inspection, a good rule of thumb when it comes to receptacles:
- Any fixed in place appliance should not exceed 50% of a branch circuit amperage rating
- Example: if the appliance is on a 20 amp branch circuit, it should not be rated at more than 10 amps.
- Any cord and plug connected appliance should not exceed 80% of a branch circuit amperage rating
- Example: if the cord and plug appliance is on a 20 amp branch circuit it should not be rated at more than 16 amps.
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