What’s the difference? I have a copper 4AWG wire connected to the bonding jumper (green screw) inside a 200-amp panelboard. The wire is connected to a grounding rod (acorn and 8 feet). Is the wire a GEC or an EGC?
Equipment grounded conductors refer only to the copper grounding wires of the branch circuit wires?
It’s actually quite easy to figure out.
A GEC is a grounding electrode conductor. It’s that sole conductor between the ground rod or metal water pipe in direct contact with the earth serving as the required grounding electrode source to serve the building if in direct contact with the earth.
An EGC is an equipment grounding conductor which comes from the inside of a panel and is installed with a feeder or branch circuit.
To expand on Davids comments…remember this…the GEC is a function of connection to a grounding electrode(ie: Ground Rod,Ufer,Water Pipe,Ground Ring…etc.)…EGC should really be considered a bonding conductor…
Typically if you see a 4 AWG in the panel…chances are it is for Water Pipe Electrode, Ufer possibly but remember Ground Rods usually are 6 AWG…and in some cases 8 AWG for a 100A service…but while a 4 AWG indeed can be used to a rod if they want…likely not.
Just remember if new construction chances are you will have plastic water lines coming in…so if you do and see a 4 AWG…look for a Ufer then move down the list.