Gilf
Member
- Location
- Ankara, Turkey
Hi,
I am lost here in the pool of definitions. Now this may come across as a silly question however please help me clarify my mind as I have absolutely confused myself as I read more about this topic.
Now, the problem is that I have this project where I may have designed the PE cables with wrong sizes because I may have understood the standard wrong.
So firstly what I'm trying to find if I have sized correctly (as in by PE conductor) is the earth cable (or conductor) that we run along with the live conductors. As in 3 phase + neutral + ground. To be more specific, for example I have panel LP-1 that is fed from MDP. I run a 4x25mm2 multicore cable and a 16mm2 ground from MDP to LP-1 for feeder cable. (This is what I have been referring to as PE, please correct me if the terminology I use is wrong as I believe this is the main problem. I live in Europe by the way)
Now I look at NFPA 70 Definitions section, and these are the definitions I come accross;
Grounding Conductor, Equipment (EGC). The conductive path installed to connect normally non–current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor,or both.
It also states in the NFPA handbook that "This definition was revised for the 2008 Code to point out that the equipment grounding conductor is the entire conductive path back to the grounded conductor, or to the grounding electrode conductor or both conductors. FPN No. 1 points out that equipment grounding conductors also serve as bonding conductors. Proper sizing of equipment grounding conductors is found in 250.122 and Table 250.122.
So what I did was that I went and had a look at Table 250.122 and sized the ground that runs with the hot and neutral of the circuit (this is what I will refer to this as from here on as I may have been referring to ground wrong in order to avoid further confusion) based on this table.
This is how the calculation goes:
I determined the loads in amps. Selected a circuit breaker based on load with additional spare capacity as required. Then I refer to this table 250.122. So for example if the breaker 15A I determine from the table that I should use 14awg ground in that circuit. Now where this gets more confusing for me is that for 40A breaker the ground size 10Awg and it is the same for 60A.
Am I doing this correctly? Or have I completely messed it up?
I am lost here in the pool of definitions. Now this may come across as a silly question however please help me clarify my mind as I have absolutely confused myself as I read more about this topic.
Now, the problem is that I have this project where I may have designed the PE cables with wrong sizes because I may have understood the standard wrong.
So firstly what I'm trying to find if I have sized correctly (as in by PE conductor) is the earth cable (or conductor) that we run along with the live conductors. As in 3 phase + neutral + ground. To be more specific, for example I have panel LP-1 that is fed from MDP. I run a 4x25mm2 multicore cable and a 16mm2 ground from MDP to LP-1 for feeder cable. (This is what I have been referring to as PE, please correct me if the terminology I use is wrong as I believe this is the main problem. I live in Europe by the way)
Now I look at NFPA 70 Definitions section, and these are the definitions I come accross;
Grounding Conductor, Equipment (EGC). The conductive path installed to connect normally non–current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor,or both.
It also states in the NFPA handbook that "This definition was revised for the 2008 Code to point out that the equipment grounding conductor is the entire conductive path back to the grounded conductor, or to the grounding electrode conductor or both conductors. FPN No. 1 points out that equipment grounding conductors also serve as bonding conductors. Proper sizing of equipment grounding conductors is found in 250.122 and Table 250.122.
So what I did was that I went and had a look at Table 250.122 and sized the ground that runs with the hot and neutral of the circuit (this is what I will refer to this as from here on as I may have been referring to ground wrong in order to avoid further confusion) based on this table.
This is how the calculation goes:
I determined the loads in amps. Selected a circuit breaker based on load with additional spare capacity as required. Then I refer to this table 250.122. So for example if the breaker 15A I determine from the table that I should use 14awg ground in that circuit. Now where this gets more confusing for me is that for 40A breaker the ground size 10Awg and it is the same for 60A.
Am I doing this correctly? Or have I completely messed it up?
