Isolated ground conductor size

[hhsting]

Isolated ground conductor for noise purposes how do you size them?

 

[MrJLH]

Are you referring to the conductor from the PLC/DCS panel to the grounding grid?

 

[infinity]

For a branch circuit size like a regular EGC.

 

[petersonra]

Isolated ground conductor for noise purposes how do you size them?

depends on what you mean "for noise purposes". Chances are it will have no effect whatsoever on "noise" so the size just doesn't matter. If it is also serving as the branch or feeder circuit EGC than the normal EGC sizing rules apply.

 

[LarryFine]

For a branch circuit size like a regular EGC.

This.

 

[Speedskater]

For an 'Isolated Ground' circuit, the EGC (Safety Ground) needs to be the same size (or larger) than the Hot & Neutral conductors.

 

[infinity]

For an 'Isolated Ground' circuit, the EGC (Safety Ground) needs to be the same size (or larger) than the Hot & Neutral conductors.

What if the circuit is 50 amps and has #8 AWG conductors? 250.122 says that for that 50 amp circuit the EGC only needs to be #10.

 

[drcampbell]

Install whatever the noise engineer calls for on the blueprint/in the specifications and pays for, or what the NEC specifies, whichever is larger.

 

[kwired]

depends on what you mean "for noise purposes". Chances are it will have no effect whatsoever on "noise" so the size just doesn't matter. If it is also serving as the branch or feeder circuit EGC than the normal EGC sizing rules apply.

If it is truly "isolated" then there should be no connection to anything else at the feeder tier level, sizing to T250.122 and the branch circuit OCPD should be sufficient.