seperatly derived system

[AZJoe]

Hello;
277/480 3ph grounded system with no neutral loads served,system is grounded and bonded at first disconnect, EGC taken to secondary XFMR with secondary XFMR 480/120-240, if secondary XFMR is grounded and bonded seperatly wont this create multiple ground fault paths for original system between the two grounding electrodes. Can the secondary neutral just be bonded to primary EGC.
Thank You: AZJoe

 

[raider1]

No.

Keep in mind the fault current wants to require to the source. The transformer is the source where the fault current from the secondary want to return to not the utility transformer.

Hope this makes sense.

Chris

 

[don_resqcapt19]

Hello;
277/480 3ph grounded system with no neutral loads served,system is grounded and bonded at first disconnect, EGC taken to secondary XFMR with secondary XFMR 480/120-240, if secondary XFMR is grounded and bonded seperatly wont this create multiple ground fault paths for original system between the two grounding electrodes. Can the secondary neutral just be bonded to primary EGC.
Thank You: AZJoe

Multiple paths between grounding electrodes is not an issue. The issue is when you have multiple paths from a grounded conductor to earth. The grounded conductor of the 480/277Y system and the grounded condutor of the 120/240 volt system are not the same grounded conductor. Both must be connected to earth at a single location.
You are not permitted to use the primary EGC as the secondary grounding electrode conductor, but there will be a physical path between the primary EGC and the secondary grounded conductor in a code compliant installation.

 

[Smart $]

.... Can the secondary neutral just be bonded to primary EGC.
Thank You: AZJoe

The secondary neutral is required to be bonded to the nearest of water pipe or structural steel electrodes. If neither of those exist in the building or structure, the neutral must be connected to the building or structure grounding electrode system.