One more that we kid about is that if the raceway is permitted as an EGC. Pull out the EGC and the violation is fixed. Ground wire = violation, no ground wire = compliance.
Good one, Russ. Puzzles me too. From my knowledge of fault calculations, it makes no sense either especially considering a longer circuit, all else equal, would have lower prospective fault current at the load. Maybe a physicist could chime in 😁
Russ, Thank you for the video. I'm struggling with this as well. It has drove me crazy! Does this only apply if the conductors are increased because of voltage drop? What if my equipment required a #10 on a 30 amp breaker but i only had #8 on the truck and i'm just wanting to get the job done. Does this rule still apply?
Russ, from discussing with some other code experts the intent of the code in increasing the size of the EGC proportionally when the ungrounded conductors are increased in size (for voltage drop primarily) is to ensure a low impedance effective ground fault current path that assures opening of overcurrent deviced in a ground fault situation. Hypothetically increasing/decreasing the size of the OCPD doesnt seem relevant here.
I don’t see how this possibly be a safety concern ONLY SOMETIMES.... A 600 foot long circuit on 60 A breaker wired with 3 AWG circuit wires and an 8 AWG EGC is a violation because circuit conductors were increased in size from 6 AWG but EGC remained the same size. ???? But a 600 foot long circuit on a 100 A breaker wired with 3 AWG circuit wires and 8 AWG EGC where circuit wires were not increased in size is perfectly code compliant!!!! The impedance argument makes no sense! The conductor impedance is EXACTLY the same for both of these circuits! The 100A breaker will trip fine, But somehow the 60A breaker won’t trip because of voltage drop??? I don’t buy the argument. It defies the laws of physics.
One more that we kid about is that if the raceway is permitted as an EGC. Pull out the EGC and the violation is fixed. Ground wire = violation, no ground wire = compliance.
Good one, Russ. Puzzles me too. From my knowledge of fault calculations, it makes no sense either especially considering a longer circuit, all else equal, would have lower prospective fault current at the load. Maybe a physicist could chime in 😁
Russ, Thank you for the video. I'm struggling with this as well. It has drove me crazy! Does this only apply if the conductors are increased because of voltage drop? What if my equipment required a #10 on a 30 amp breaker but i only had #8 on the truck and i'm just wanting to get the job done. Does this rule still apply?
Russ, from discussing with some other code experts the intent of the code in increasing the size of the EGC proportionally when the ungrounded conductors are increased in size (for voltage drop primarily) is to ensure a low impedance effective ground fault current path that assures opening of overcurrent deviced in a ground fault situation. Hypothetically increasing/decreasing the size of the OCPD doesnt seem relevant here.
I don’t see how this possibly be a safety concern ONLY SOMETIMES....
A 600 foot long circuit on 60 A breaker wired with 3 AWG circuit wires and an 8 AWG EGC is a violation because circuit conductors were increased in size from 6 AWG but EGC remained the same size. ????
But a 600 foot long circuit on a 100 A breaker wired with 3 AWG circuit wires and 8 AWG EGC where circuit wires were not increased in size is perfectly code compliant!!!!
The impedance argument makes no sense!
The conductor impedance is EXACTLY the same for both of these circuits!
The 100A breaker will trip fine, But somehow the 60A breaker won’t trip because of voltage drop??? I don’t buy the argument.
It defies the laws of physics.