250.32 vs 250.50 Bonded Together

[ron]

A graphic shown in the NEC handbook for 250.32 shows grounding electrodes installed at the main building and at a separate building. The only interconnection being an equipment grounding conductor. 250.50 indicates to bond all grounding electrodes together to form the grounding electrode system.

Does the EGC satisfy that requirement in 250.50, or is an additional grounding electrode conductor need to be run from the 2 separate electrodes to bond together to be a grounding electrode system. I'm thinking the EGC is recognized also performs bonding so an additional GEC is not needed..

Definitions:
Grounding Electrode Conductor.
A conductor used to connect the system grounded conductor or the equipment to a grounding electrode or to a point on the grounding electrode system.

Grounding Conductor, Equipment (EGC).
A conductive path(s) that is part of an effective ground-fault current path and connects normally non–current-carrying metal parts of equipment together and to the system grounded conductor or to the ground electrode conductor, or both.
Informational Note No. 1: It is recognized that the equipment grounding conductor also performs bonding.

 

[infinity]

A graphic shown in the NEC handbook for 250.32 shows grounding electrodes installed at the main building and at a separate building. The only interconnection being an equipment grounding conductor. 250.50 indicates to bond all grounding electrodes together to form the grounding electrode system.

Are you saying that since the EGC run with the feeder to the separate structure is connected to the GES at the first structure then a GES at the second structure is not required?

 

[wwhitney]

250.50 indicates to bond all grounding electrodes together to form the grounding electrode system.

250.50 says "at each building or structure". So it does not impose a requirement to bond grounding electrodes at building 1 to grounding electrodes at building 2.

Cheers, Wayne

 

[ron]

Are you saying that since the EGC run with the feeder to the separate structure is connected to the GES at the first structure then a GES at the second structure is not required?

No. A GES is needed at each structure in my example.

I was trying to rationalize how to bond all grounding electrodes together per 250.50, thinking that I need to run a GEC between the 2 grounding electrodes (one at building 1 and one at building 2). If that were required, I thought maybe the EGC would satisfy that need, since the definition of an EGC says It is recognized that it also performs bonding.

 

[infinity]

No. A GES is needed at each structure in my example.

I was trying to rationalize how to bond all grounding electrodes together per 250.50, thinking that I need to run a GEC between the 2 grounding electrodes (one at building 1 and one at building 2). If that were required, I thought maybe the EGC would satisfy that need, since the definition of an EGC says It is recognized that it also performs bonding.

The two separate GES's are not required to have additional bonding like a GEC connecting them together but they actually are bonded together by the EGC.

 

[wwhitney]

I was trying to rationalize how to bond all grounding electrodes together per 250.50, thinking that I need to run a GEC between the 2 grounding electrodes (one at building 1 and one at building 2). If that were required . . .

If that were required (it is not), a bonding jumper would suffice, no need for a GEC. And an EGC can perform the role of a bonding jumper. If the required bonding jumper size were larger than the required EGC size, then you'd need to upsize the EGC accordingly to get it to do double duty.

Cheers, Wayne

 

[jaggedben]

250.50 says "at each building or structure". So it does not impose a requirement to bond grounding electrodes at building 1 to grounding electrodes at building 2.

Cheers, Wayne

Correct. And the requirement for the EGC to bond them together is an implicit consequence of other requirements. Namely 250.24 requires both GEC and EGC to be bonded to neutral at the structure with the service, and 250.32 requires the GES at the separate structure to be bonded to the EGC.

 

[electrofelon]

But what is a gray area is how close a grounding electrode must be for it to be present at a building or structure. For example, say you have two buildings that are 10 ft apart. Also say you pound some ground rods between the two buildings. I would be using that single set to ground both buildings.

 

[infinity]

But what is a gray area is how close a grounding electrode must be for it to be present at a building or structure. For example, say you have two buildings that are 10 ft apart. Also say you pound some ground rods between the two buildings. I would be using that single set to ground both buildings.

Correct, the NEC is silent as to distance required for a GES to be considered serving a structure. It would be simpler if the code stated all separate structures must have their own GES.