Mike Dolt Enterprises
Mike Dolt Enterprises
User: Miguel c, Location: Barranquilla colombia
Asked on: Friday, May 28, 2021 at 2:45 pm EDT
Answered on: Thursday, June 20, 2024 at 11:01 am EDT
Question: Hi guys, here I have this hypothetical scenario.We have an effective ground fault current path, an excellent 8 copper EGG, suddenly someone who didn't know much about electricity decided to change the EGC to another type of EGC material with an impedance of 9.5 ohms, but the phase conductor is an excellent 8 AWG wire and has an impedance of 0.05 (9.5 + 0.05 omhs = 10 omhs)Now there is a ground fault, 120V ÷ 10 = 12A, but the OCPD breaker is rated 30A, therefore it does not trip, now we could say that we no longer have an effective ground fault current path because the installation does not meet the code requirments for the EGFCP definition. However, the question is: Would someone be exposed to receiving a possible electric shock? or Could we assume that the installation continues to be safe since the neutral and the EGC are linked together at one point (MBJ)? What would be the load metal enclouse voltage to earth? 0 V?
Exposure to Electric Shock
Yes, someone could still be exposed to an electric shock, even though the EGC does not meet the code requirements for an effective ground fault current path. The 12A ground fault current is enough to cause a potentially fatal shock.
Ground Fault Protection
The OCPD breaker is not providing ground fault protection because it is rated too high. It would need to be rated at 10A or less to trip within the required time frame.
Installation Safety
The installation is not considered safe because it does not meet the code requirements for an effective ground fault current path. This means that the neutral and EGC bonding at the MBJ may not provide sufficient protection against electric shock.
Load Metal Enclosure Voltage to Earth
The load metal enclosure voltage to earth will depend on the following factors: Impedance of the EGC Ground fault current Resistance of the neutral conductorIn this case, assuming the neutral conductor has negligible resistance, the load metal enclosure voltage to earth would be:
(9.5 ohms / 10 ohms) = 114VTherefore, the load metal enclosure would be at 114V to earth, which is still a dangerous voltage.120V
Conclusion:
The installation is not safe and poses a risk of electric shock. An electrician should be called to replace the EGC with one that meets the code requirements for an effective ground fault current path and install a properly rated OCPD breaker. Flag for review