jwelectric said:
Just what is 3 and 4 above?
Are they REQUIRED to connect to earth?
In an ungrounded Delta system is there a bond to the service grounded conductor? Is there a service grounded conductor?
Does the equipment GROUNDING (earthling) conductor not connect to the earth here?
?Just what is 3 and 4 above??
3] Electrode grounding/earthing conductor(s)
4] Equipment grounding/bonding conductor, conduit, or bar
I can?t answer the question of ?what is? it because I don?t understand what you?re asking.
?Are they REQUIRED to connect to earth??
You know that they are, so what are you asking about ?
250.52(A)(1)+(2) even specifies that the ?direct contact with the earth? must be at least 10?
250.52(A)(3)+(4) specifies 20? of earth contact
250.53(G) has an 8? ?in contact with the soil?
You know these rules and there?s nothing more I can add so once again, I don?t understand what you?re asking me to add.
?In an ungrounded Delta system is there a bond to the service grounded conductor? Is there a service grounded conductor??
No and No
?Does the equipment GROUNDING (earthling) conductor not connect to the earth here??
250.4(B)(1)
Yes, it connects the equipment to earth thru its connection to the electrode system. . Ground
ing and ground
ed are two different things. . The absence of a ground
ed conductor does not affect the ground
ing conductors requirements. . The electrode earthing handles lightning and the equipment bonding handles overcurrent to allow the OCPD to operate.
The only difference is that the equipment bonding operates OCPD on the
first fault in a grounded system but not until the
second fault on an ungrounded system. [250.4(B)(4)]
The ungrounded system has no ?star?. . It only has 3 points. . It connects electrode earthing, equipment bonding, and enclosures so there?s no connection to the transformer to operate OCPD on the first fault. . The first fault grounds the system, grounds the transformer coil/windings and allows for OCPD operation on the second fault.
The lack of response of the ungrounded system to the first fault shows the response of an improperly grounded grounded system. . The ?response? of the improperly grounded grounded system is to continue to operate equipment and sit there and wait until a person touches a certain piece of metal. . It?s like a loaded gun except you don?t even know it?s there waiting for you.
David
PS We lost the requirement for ground detector lights in 1999NEC, didn?t we ?