Ground Sizing

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jim3394

Member
I would just like some clarification on ground conductor sizing for a 30 Amp 120 Volt circuit. I am reading two articles that seem to fight each other as far as downsizing and not downsizing. Bootom line, can I run a number 12 thhn for the ground conductor, and am i reading it correctly that it would not be the case for lets say a 240 volt water heater circuit???
 

curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
Occupation
Electrical Contractor
Have you ready 250.122 and looked at table 250.122?

Bottom line answer is NO.

What are you reading that says it can be reduced in size?
 

kwired

Electron manager
Location
NE Nebraska
What two articles are you reading?

250.122 is what applies.

For any overcurrent device larger than 20 amps but no larger than 60 amps you must use a minimum 10AWG copper EGC.

250.122(A) does state that in no case shall they be required to be larger than the circuit conductors supplying the equipment.

So a motor circuit with 12 AWG circuit conductors and a 30 amp overcurrent device would be allowed to have 12 AWG EGC but only because the circuit conductors are allowed to be 12 AWG.
 
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