separately derived systems GEC

[626alexnava]

Good afternoon I tried looking up the code for this response from an inspector so I can further educate myself by looking at 250.30, and 250.24 but just wanted to see if a grounding electrode conductor at my step down transformer is necessary (meter, transformer, and distribution panel are outdoors) even if my service main breaker panel and distribution panel have grounding electrode conductors already. According to the inspector it is not required at the transformer. Let me know if he is correct or if I do need a GEC at xfmr. Thanks in advance.

Inspector Response: “The Neutral-Ground bond occurs at the switchboard downstream of the transformer for the separately derived system so there would not be any ground rods or GEC at the delta-Wye transformer itself.”

 

[infinity]

Where are you installing the system bonding jumper?

 

[augie47]

A connection to the GES is required for a SDS transformer. It should be connected where the MBJ is installed as shown on the pictorial below.

 

[626alexnava]

SSBJ will be from step down to distribution panel. MBJ at main breaker panel and Distribution panel.

 

[infinity]

SSBJ will be from step down to distribution panel. MBJ at main breaker panel and Distribution panel.

That would be the system bonding jumper. Two methods either SBJ at the transformer or at the panel. Sounds like you're using this method:

 

[jaggedben]

Good afternoon I tried looking up the code for this response from an inspector so I can further educate myself by looking at 250.30, and 250.24 but just wanted to see if a grounding electrode conductor at my step down transformer is necessary (meter, transformer, and distribution panel are outdoors) even if my service main breaker panel and distribution panel have grounding electrode conductors already. According to the inspector it is not required at the transformer. Let me know if he is correct or if I do need a GEC at xfmr. Thanks in advance.

Inspector Response: “The Neutral-Ground bond occurs at the switchboard downstream of the transformer for the separately derived system so there would not be any ground rods or GEC at the delta-Wye transformer itself.”

Is the service disconnect you mention on the primary or secondary side of the transformer and where is the service point?

 

[626alexnava]

Is the service disconnect you mention on the primary or secondary side of the transformer and where is the service point?

Utilities come into gear that separates meter section and main breaker with two service breakers section. Each breaker feeds its own step down transformer which then feed its own distribution panel. Prints show GEC at main panel and distribution panel only. All outdoors.

 

[infinity]

Prints show GEC at main panel and distribution panel only. All outdoors.

And why isn't that correct? Don't the distribution panels have the system bonding jumpers?

 

[626alexnava]

I just wanted to verify that I also didn’t need a ground rod with ground loop for GEC into the step down transformer as well. 250.30(A)(1) show the two options thank you guys for helping and responding.